Biomedical research aims to improve individual health through more effective medical diagnostics, clinical care and therapeutics as well as through public health practices oriented to the community. It encompasses fields such as clinical sciences, epidemiology, basic sciences, drug and vaccine development, and clinical trials. The quality of biomedical research can be significantly enhanced by operations research, behavioural research and research in health economics, policy and management. Sheela Godbole and Sanjay Mehendale detail some of this research

The last 25 years have seen immense contributions to the field of biomedical research on HIV/AIDS. Landmark studies on the HIV immunopathogenesis (the disease process and its effect on the immune system), and in virology, drug development and prevention interventions, have provided new insights not only into HIV/ AIDS, but other diseases as well.

Research in the West

Biomedical research in HIV/AIDS began in the West. The first reports of the new clinical syndrome were from the USA. The virus causing AIDS was identified in France and the USA in 1983. The ELISA test to screen for antibodies to HIV infection was developed a year later. Subsequent studies in Europe and the USA helped to define the progression of HIV infection in human beings, identify risk factors for transmission and collect information on the virus at a molecular level as well as on the different systems of the human body. Research on opportunistic infections and co-infections has helped formulate guidelines and strategies for treatment.

The first drug found to be active against HIV was Zidovudine. This had been developed as a cancer treatment in 1964 but was then found ineffective for this purpose. Decades later, it was tested and found to suppress the replication of HIV in the laboratory setting. In 1987 it was approved as the first antiretroviral drug for HIV infection. It continues to be used even today.

The approval of Zidovudine has been followed by an expansion in research on drugs of different types targeting HIV. The new antiretroviral drugs and various multi-drug combination treatment strategies have led to a substantial reduction in the mortality (death) and morbidity (illnesses) due to HIV/AIDS. The development of quality generic antiretroviral drugs, and reductions in their costs over time, has increased access to these drugs in resource-limited countries.

Another milestone in antiretroviral drug development is the use of these drugs to treat pregnant HIV positive women during pregnancy and immediately after childbirth to decrease the probability of transmission of HIV to the foetus.

Research in India

HIV was first identified in India in 1986, in Chennai, shortly after the Indian Council of Medical Research (ICMR) initiated surveillance for HIV. Surveillance was later taken over by the National AIDS Control Organisation (NACO), set up under the Ministry of Health and Family Welfare. The National AIDS Research Institute (NARI) was established in the early 1990s. Currently, research on HIV/AIDS is conducted in various ICMR institutions, other research institutes, medical colleges, hospitals, voluntary organisations and also in public sector agencies.

Funding for research in India comes from national sources like the ICMR, NACO, the Department of Biotechnology, and the Department of Science and Technology; from international agencies such as WHO, USAID, UNAIDS, the National Institutes of Health in the USA, the UK Medical Research Council, the UK Department for International Development, Indo-French collaborations, and from international foundations such as the International AIDS Vaccine Initiative, Gates Foundation and the Clinton Foundation.

Regulatory mechanisms

Various research institutes set up regulatory mechanisms to maintain scientific and ethical integrity during research. Typically, research protocols need approvals from an institutional ethics committee and a scientific advisory committee. Studies field testing new investigational products must be approved by the Drugs Controller General of India (DCGI). In addition, projects funded by international agencies need approvals by the health ministry’s screening committee, the ICMR and NACO. In certain special cases, approvals from other agencies are also required, for example, where genetic research or research on genetically engineered substances is proposed.

The ICMR has established ethical guidelines for the conduct of biomedical research in India. In addition, clinical trials require compliance with ‘Schedule Y’ guidelines as well as the Guidelines for Good Clinical Practices by the DCGI and the International Conference on Harmonisation. Some project sites have also established community advisory boards to interface between researchers and the community. The inputs of these advisory boards are valuable not only in planning and implementing studies and trials, but also in the development of the protocol itself.

Descriptive epidemiology

Extent of spread of HIV in India and disease burden estimation
Epidemiology is the study of factors influencing the health and illness of populations. It drives preventive and therapeutic research as well as public health interventions. Typically, epidemiologic studies describe the extent of the disease in various sub-populations, the rates of its occurrence, and risk factors associated with the disease. This information is analysed and used to plan prevention and control interventions.

Numerous epidemiologic studies have been undertaken in India since the first evidence of HIV infection in 1985-1986 marked the beginning of the epidemic. Epidemiological data on HIV/AIDS in India is derived from annual sentinel surveillance, ongoing testing in antenatal clinics and blood banks, research studies, reporting of AIDS cases and information generated from mortality statistics.

Studies have shown that, 20 years after the first documented HIV infection in India, the epidemic is no longer restricted to high-risk groups in urban areas. It has spread to low-risk populations in rural and urban areas.

The government uses annual sentinel surveillance primarily to monitor HIV epidemic trends in populations with high risk behaviour: female sex workers (FSW), intravenous drug users (IDUs), men having sex with men (MSM), long distance truck drivers and migrant workers. Trends in the general population are monitored by observing HIV prevalence (the percentage of people within a particular group infected at any given time) among pregnant women. This data has been used to estimate the country’s HIV disease burden as well.

It was estimated that in 2006, India had about 5.26 million people, aged 15 to 49, living with HIV. In July 2007, HIV estimates for India were revised, and it is believed that there are about 2.5 million HIV infected adults (range 2.0 to 3.1 million) currently living with HIV.

The various epidemiological studies also give information about who is infected and how. It is believed that heterosexual contact is responsible for about 85% of all new HIV-1 infections in India. About 75% of HIV infected persons are from the states of Andhra Pradesh, Karnataka, Tamil Nadu and Maharashtra, constituting 30% of the country's population. It is believed that, nationally, 5.66% of patients with sexually transmitted infections (STI) are HIV infected. The percentage is 8.44% for female sex workers and 10.16% for injecting drug users. About 9% of tuberculosis patients also have HIV infection. The all-India HIV prevalence among pregnant women is 0.88%. However, there are geographical and urban-rural variations. http://www.nacoonline.org/fnlapil06rprt.pdf

A study in Pune district on pregnant women showed a prevalence of 0.7% in the year 2000. A study among pregnant women conducted by the Comprehensive Rural Health Development Project and NARI in Jamkhed, in rural Ahmednagar district in July-August 2001 showed HIV prevalence of 0.42%.

The national HIV prevalence among pregnant women in India was observed to be 0.36% as per data released in July 2007. HIV prevalence in rural areas is lower than urban areas and there are also geographic variations.

Incidence of HIV
Prevalence of HIV is a measure of the total number of cases of HIV in a population at a specific point in time, compared to the total population at risk of getting that infection. Incidence is the number of new cases of HIV infection occurring in a given time period, compared to the total population at risk of getting that infection. Prevalence tells us about the existing burden of the disease. Incidence can give better information on the risk that various groups have of contracting the disease, as well as the number of new infections that are contributing to the spread of the disease. Incidence is best measured in cohort studies that monitor a selected group or cohort over a period.

The first data on HIV incidence in India emerged from prospective cohort studies in Pune. Starting in 1993, NARI screened men, women and sex workers attending sexually transmitted disease (STD) clinics in Pune, and followed them for four years. Spouses of STD patients were also tested periodically over this time. The overall HIV sero-prevalence among STD clinic attendees at the time of screening was found to be 22.9% (1993-1997).

Factors likely to increase the risk of HIV transmission from a cohort
Heterosexual contact was found to be an important risk factor in both men and women. Other important risks were: being over 20 years old, not living with one’s family, having had a tattoo any time after 1986, a past or present history of STIs, having multiple sexual partners and practising receptive anal intercourse. (STIs or sexually transmitted infections are infections that are transmitted during close bodily contact during intercourse and include but are not limited to STDs or sexually transmitted diseases. STDs present with symptoms usually in the genital areas.) The use of condoms was associated with a low risk of HIV. Both a prior history of genital ulcer or warts and current diagnosis of genital ulcer, discharge and warts were associated with high HIV prevalence.

The overall incidence rate of HIV was observed to be 7.6% per year in this Pune cohort of STD patients – that is, 7.6% of the persons enrolled in this cohort became HIV- positive over the year. The incidence of HIV was highest among sex workers – one in five commercial sex workers (CSWs) would become HIV-positive each year. Also, 9.7% of men reporting a recent history of exposure to sex workers became HIV-positive each year compared to 5.6% among those with no such history.

The same Pune-based cohort study – of STD clinic patients and their spouses -- documented an HIV prevalence of 14% and incidence (in 1996) of 5.4% in women who reported that they were married and monogamous.

The beginnings of a decline in HIV

Very recently published data from the same cohort reports the first direct evidence of a decline in HIV incidence rates in female sex workers and male STD patients over the last 10 years. However, there is no evidence of a change in the risk of HIV infection for wives of male STD patients. This stresses the need for additional targeted HIV prevention interventions. Data has also emerged from sentinel surveillance in South India that supports a decline in HIV incidence.

Most Indian sero-epidemiologic studies have focused on estimating HIV prevalence in different target groups such as sex workers, STD clinic attendees, truckers, hospital attendees and blood donors. A strong relationship between STIs and HIV infection has been documented in many studies. A study of 670 long-distance truck drivers in Nagpur showed that 15.2% of them were HIV-positive and 21.9% were infected with syphilis. Studies in the same group in Mumbai have shown an STI prevalence of 8-8.5 %.

In addition, results are awaited from an ongoing study, Integrated Biological and Behavioural Assessment, to assess the impact of targeted interventions in six high prevalence states in India, led by Avahan, the India AIDS initiative of the Bill and Melinda Gates Foundation. As part of this study, surveillance among the targeted populations is planned to be conducted thrice over a period of five years.

Studies in blood donors have reported the seroprevalence among voluntary and replacement blood donors. Studies in severe and moderate patients of haemophilia in western Maharashtra showed that 3.8% were positive for HIV between 1995 and 2000. Over the last few years, the Drug Control Authority has taken many steps to improve the quality of blood for transfusion -- equipping blood centres with tests for screening of blood, emphasising the need for uniform procedures for donor selection, donor deferral and validation of equipment. This seems to have led to a decrease in the prevalence among blood donors.

An analysis of data from 294,050 women attending 216 antenatal clinics and 58,790 men attending 132 STI clinics in 2000-04 reported that HIV-1 prevalence among women in the south fell from 1.7% in 2000 to 1.1% to 2004, while for men attending STI clinics in the south, there was a reduction of 7.6% in HIV-1 prevalence. Results from a survey for HIV in urban and rural populations carried out under the auspices of the National Family Health Survey-III in 2006 have been used along with a revised methodology to make preliminary estimates of approximately 2.0-3.1 million HIV infected people in India, with a prevalence of 0.36%. http://www.unaids.org/en/MediaCentre/PressMaterials/
FeatureStory/20070704_India_new_data.asp

HIV and TB

Tuberculosis is not a risk factor for HIV infection. However, HIV-infected individuals become immunodeficient and as a result often develop the commonest endemic disease in the country - tuberculosis.

TB is the most common HIV-related infection in India. The incidence of TB in HIV-infected individuals is much higher than in the general population. People infected with TB and HIV have a 5-8% annual risk and a 30% or greater lifetime risk of developing active TB. Swaminathan and others reported an incidence rate of 7.1 per 100 person years in skin test positive and 6.9 per 100 person years in skin test negative HIV-positive individuals in south India. Therefore, many studies have looked at HIV infections among tuberculosis patients. Increasing trends of HIV prevalence, rising from 3.2% in 1991 to 20.1% in 1996, and to 30.04% in 2001, have been observed among newly diagnosed tuberculosis patients in Pune (NARI data).

Basic sciences

Basic science research can provide guidance in understanding the interactions between the disease-causing pathogen and the human body at the cellular and molecular levels. It can also help devise methods or interventions for the prevention and control of diseases at individual and community levels.

Diagnostic tests for HIV
Most commonly available tests detect HIV-specific antibodies in blood; evidence of such antibodies is considered diagnostic of HIV infection. Other tests can detect the p24 antigen (which is specific to HIV) or HIV-specific DNA in a polymerase chain reaction (PCR) assay or test. These tests are more specific – they are less likely to give a false positive result. The PCR assay was used in the diagnosis of HIV in India as early as the late 1980s.

Efforts have been made to use cost-effective strategies for large-scale HIV testing. Studies at NARI have validated the use of dried blood spots for HIV testing. This method has been used in many field surveys including the most recent survey by NFHS. Studies have also demonstrated the feasibility of using pooled blood samples to test for HIV-1 viral RNA in order to diagnose acute primary HIV-1 infection and to estimate HIV incidence. The multistage pooling method for detection of HIV-1 RNA was found to be less likely than the p24 antigen method to give a false negative result. It was also one-fifth the cost of the p24 antigen assay. Pooling samples for RNA detection was shown to be effective in estimating current incidence rates. The reduced costs also make them more practical for use in developing countries.

Research has been conducted to validate the use of kits for salivary samples and different testing strategies. The standard tests like ELISA or Rapid test can only tell if a person is infected, but not when the infection might have occurred. However, ‘detuned ELISA’ or ‘BeD capture’ ELISA are newly developed assays that can identify recent (as opposed to old) infections among samples from known HIV positive people. These tests can be used to calculate the incidence of HIV infection in a community.

CD4 tests to monitor treatment
HIV infection causes impairment in the immune system as the disease progresses. This is the basic cause of the symptoms and disease syndromes associated with HIV/AIDS.

A typical immune response to HIV infection involves the development of both antibodies, that can destroy the free virus circulating in the blood, and cell-mediated immune responses that destroy cells infected with HIV.

Lymphocytes are a type of white blood cell to fight off infection. HIV primarily affects CD4 lymphocytes, that first detect invading pathogens and initiates body’s immune response. Another type of white blood cell, the CD8 cell, is capable of destroying HIV infected cells in the body. The cytotoxic T lymphocyte (CTL) assay can determine the absolute numbers and proportions of T type of white cells in the body. A high cytotoxic T lymphocyte (CTL) response is associated with an increased survival time in HIV-infected individuals.

However, despite these immune responses, HIV-1 does not get eliminated by the immune system. The virus replicates continuously within immune cells like the CD4 cells, destroying them. The CD4 count is used as a marker for the progression of HIV disease. These numbers are also used to decide when to start antiretroviral therapy and to monitor it. They are also relevant for prophylaxis or prevention of opportunistic infections in those exposed to HIV. Thus estimation of CD4 counts is important in HIV disease management.

One of the key areas of research in India is development of low-cost diagnostic tests for CD4 cell count and viral load.

Normal ranges of CD4 and other immune cell counts in the healthy adult population in India have been estimated by the ICMR in a multicentric study and various smaller studies. They found significant differences between HIV positive and HIV negative tuberculosis patients. They also noted that CD4 counts were lower in HIV positive patients who had both extrapulmonary and pulmonary tuberculosis, than in those who had either pulmonary or extrapulmonary tuberculosis. This has guided scientists to undertake studies about anti-TB prophylaxis in HIV infected people.

Studies of cytotoxic T cell responses in asymptomatic HIV-infected individuals and in recently infected people found immune responses across different HIV subtypes. This raises hopes that vaccine candidates for one HIV subtype may be effective for other HIV subtypes as well.

HIV viral load tests
The level of virus in a person’s blood correlates with the progress of infection and also determines how infectious that person may be to others. When a person receives triple antiretroviral therapy the virus level in his/her blood becomes so low that it is undetectable. When drug resistance develops, the viral load shoots up again.

Viral load tests are used in research studies and clinical trials. In societies where the tests are affordable they are used to routinely monitor HIV treatment. Ongoing research to develop cheaper testing for viral load in India will be useful for the government’s ART programmes.

Surveillance of HIV subtypes in India

HIV is continuously evolving and differs genetically from one geographical location to another. HIV is classified into serotypes HIV-1 and HIV-2. HIV-1 is in turn classified into three groups, M, O and N. The group M of HIV-1 consisting of 9 subtypes classified as A to K based on the analysis of their genes causes 99.6% of all human infections globally. Each subtype has multiple genotypes such as C1, C2, C3, etc. Genotype C3 is the predominant HIV-1 subtype circulating in the Indian subcontinent.

Surveillance of the different HIV-1 subtypes has important implications for developing candidate vaccines and understanding the dynamics of HIV transmission in various populations. Documenting genetic variations in different parts of the country is important for vaccine design because a vaccine protective against a subtype may not be protective against another subtype or an emerging recombinant from existing subtypes, or it may only be partially protective. It is also important to know the extent of genetic variation as this can have an impact on how easily the virus is transmitted, how the disease progresses, and in the utility of existing diagnostic tests.

A number of studies have documented the different subtypes of HIV present in India. Serological and molecular virology studies have indicated the presence of HIV 1 and 2 dual infections in western India. A number of studies have been carried out to document the prevalence of HIV 1 and HIV 2 and dual infections in western India.

The first A/C recombinant (a new mutative form of HIV that was probably derived from both A and C subtypes) was detected in Pune by NARI and additional studies from various parts of the country have identified other infections with subtypes “A”, “Thai B” and “CRF01_AE”. More importantly, Thai B is recognised as the second major subtype circulating in north-east India.

A DNA analysis of HIV-1 subtypes in India supported the epidemiologic data that the HIV-1 epidemic was introduced more recently in India than in many other parts of the world.

Human immuno-deficiency virus bank

A virus repository of more than 200 authentic, well characterised isolates of HIV has been established at the National AIDS Research Institute, Pune, and this repository continues to grow. This HIV bank has been created to help scientists interested in pursuing their research in HIV/ AIDS but who have no access to HIV viruses. It is an important national resource and is available to researchers all over the country.

Studies on HIV disease at the molecular and cellular levels

Acute primary HIV infection is characterised by dynamic virologic and immunologic events that may affect the course of the disease. In this context, studies are looking at the immunopathogenesis of HIV infection among recently HIV-infected people. Some key thrust areas for research in this field are the immunological and virological parameters of highly exposed but uninfected individuals. Some studies look at specifics of the mucosal immune responses, markers of immune activation and measures of protection, the immunology of paediatric HIV infection, human leucocyte antigen associations and monoclonal antibodies (clones from a single immune cell that can become important in developing new treatments).

A study in Pune found that HIV-1 DNA was shed in genital ulcers, increasing the risk of HIV transmission. Thus, early diagnosis of genetic ulcers in HIV-infected patients and aggressive treatment for this could reduce the chances of HIV transmission to other sex partners.

The replicative capacity of a virus during primary HIV infection is an important determinant of subsequent disease course. The replicative differences between subtype B and C are being studied.

Testing for drug resistance

Facilities for testing for HIV drug resistance have been established at a few centres in India. While this is still very expensive for routine monitoring of antiretroviral therapy, it is used to monitor for the emergence of primary and secondary HIV resistance. Such testing is also an important aspect of clinical trials using antiretroviral drugs. Development of low-cost in-house resistance testing methods is another area of research in this field.

Clinical research and HIV disease progression studies

A study from NARI has described acute primary HIV infection in those who recently became HIV positive. Recent fever, joint pain and night sweats can reasonably predict recent HIV infection in persons with high risk behaviour. Unprotected sex with CSWs and a genital ulcer were identified as independent risk factors associated with newly acquired HIV infection.

Classical natural history studies from the stage of acute infection to the stage of development of prototypic AIDS have not been done in India. Most clinical studies here have described clinical syndromes in HIV infected persons who have been infected for an unknown duration. Good studies of the progression of HIV can help in the effective care and management of people living with HIV/AIDS. They will also be useful for policy making and designing targeted interventions. Finally, they are also likely to be useful to estimate the burden of HIV infection in the country, and the impact of disability and death from HIV/AIDS.

A few observational studies on HIV positive cohorts in Mumbai and Chennai indicate that the median time for progression from HIV infection to AIDS is 7.9 years (Mumbai) and 7.6 years (southern India). Before the availability of antiretroviral therapy, median survival after diagnosis of AIDS was 12 to 18 months. This has changed dramatically since the introduction of highly active antiretroviral therapy.

Studies have reported the relationship between CD4 cell counts and clinical manifestations. In a study in Pune, presence of oral candidiasis (fungal infection of the oral cavity) and weight loss were highly predictive of low CD4 counts and can be considered markers of HIV disease progression. Absence of clinical conditions was found to be a good predictor of high CD4 counts. Such information may allow doctors to take certain decisions even in the absence of CD4 tests.

There is extensive research on HIV-related illnesses and opportunistic infections and their care and management. The first case of Pneumocystis carinii pneumonia in India was reported in Mumbai in 1993 in a commercial sex worker in Mumbai. While tuberculosis is the commonest opportunistic infections in India and may present even at higher CD4 counts, conditions like Kaposi’s sarcoma, and mycobacterium avium complex are uncommon in India. One study has reported neurological manifestations of HIV disease in 20% of patients attending their out-patient clinic and 45% of their in-patients. Recent studies have documented a significant degree of neuro-cognitive impairment among HIV-infected persons in Pune. Neurological manifestations are an important researchable area.

There is evidence to suggest that preventive therapy is useful in HIV-positive persons with tuberculin reactions greater than 5 mm. Also, preventive single drug therapy (isoniazid) should be greater than six months to provide the maximum degree of protection against TB. A trial was conducted at the Tuberculosis Research Centre, Chennai, to study preventive therapy for tuberculosis in HIV infected persons. Studies have also been conducted to assess the efficacy of directly observed therapy in HIV and TB co-infected persons at different CD4 counts. Clinical trials assessing the safety and efficacy of certain regimens of antiretroviral therapy simultaneously with anti-TB treatment are planned in HIV-TB infected patients.

There are few studies on paediatric AIDS in India. A prospective study reported that the presence of oral candidiasis was a significant independent risk factor for predicting paediatric HIV infection. Other conditions like severe malnutrition, serious bacterial infections, disseminated tuberculosis and chronic diarrhoea were also associated with increased risk of being HIV positive.

A study in Pune demonstrated that in Indian women, HIV infection is associated with a greater than two-fold risk of having an abnormal Pap smear, which subsequently puts them at increased risk for cervical cancer. The association between high risk Human Papilloma Virus (HPV) subtypes and Pap smear abnormalities was also demonstrated. A study to assess a simple method of diagnosis of cervical abnormalities using visual inspection of cervix after painting with acetic acid has just concluded at NARI Pune. This method will be compared with Pap smears, HPV testing and biopsies in HIV infected women.

As described earlier, antiretroviral drugs began to be developed and tested in the USA and Europe. India has emerged as a hub for manufacturing of generic antiretroviral therapy (ART) which has greatly improved access to antiretroviral drugs across the world. Studies from western and southern India have described response to generic antiretrovirals. The first randomised controlled antiretroviral clinical trial is currently ongoing in Chennai and Pune under the aegis of the AIDS Clinical Trials Group, a network under the US National Institutes of Health. It compares two ART regimens which have to be taken once a day with a standard, twice daily ART regimen (Combivir + Efavirenz). More clinical trials are planned.

The decision of when to start antiviral therapy is the subject of great debate, and subject to fairly frequent revision. Patients who initiate therapy with CD4 cell counts below 200 cells/mm3 have a greater risk of disease progression and death than those who initiate treatment with CD4 cell counts above 200 cells/mm3. More recently, evidence suggests that waiting for CD4+ cell count to fall below 200 cells/mm3 may put patients at increased risk of infection. This has led to recent changes in WHO recommendations.

An ongoing prevention study in HIV discordant couples will also yield useful data on whether earlier initiation of antiretroviral therapy in HIV infected persons would be beneficial in resource-limited settings like ours.

Various pilot projects have been undertaken in the indigenous systems of medicine and homoeopathy in different places in India. Ayurveda and Siddha products have shown encouraging results and extensive studies are needed to further validate these findings. The Institute of Thoracic Medicine in Tambaram, Chennai, is conducting research in the Siddha system of medicine. These studies are being coordinated by the Central Councils of Research on Ayurveda and Siddha and Homoeopathy.

Additional clinical trials have been planned with different products. NARI has set up facilities for in vitro testing of candidate products for anti HIV-activity which will be of great value for pre-clinical testing of products.

Prevention research and clinical trials

One focus of biomedical research in HIV/AIDS is to identify the limitations of existing prevention strategies and to develop new prevention technologies. Current prevention methods focus largely on behavioural change and condom use.

Vaccine development and clinical trials of existing vaccine candidates are a major focus of preventive research in India. India’s first Phase-I vaccine trial has been successfully completed in Pune and another study is ongoing. In addition to vaccine and microbicides, preventive research in India is focusing on the prophylactic or preventive use of antiretroviral therapy, female condoms and, recently, male circumcision.

Microbicides
Studies have shown that despite prevention campaigns, married, monogamous women continue to be at high risk of getting HIV through their husbands. Clearly available prevention methods are not easy to implement for women in the Indian setting. There is an urgent need to continue research to find a user-controlled means of preventing HIV infection in women.

Microbicides are compounds to protect against sexually transmitted infections (STIs) including HIV. They may offer an alternative to condoms as the most feasible method for primary prevention of HIV. They are designed to be applied inside the vagina or rectum to prevent HIV transmission during intercourse. They may or may not be effective contraceptives. At present there are more than 60 microbicide products in various stages of clinical development around the world.

A number of products have been tested in India. All the products tested in Phase I studies in Pune demonstrated a reasonable level of safety. Praneem is an indigenously developed neem-based formulation that has shown activity against HIV and sexually transmitted disease pathogens in laboratory studies. A Phase II study on Praneem has been recently completed.

Currently NARI is evaluating Tenofovir gel in a Phase II study. India was also participating in a Phase III study of Cellulose sulphate but this multi-country study was stopped early because a preliminary analysis of data found that a higher number of HIV infections occurred in the group receiving the active compound compared with the placebo. However, no woman participating in the study in India was infected with HIV.

While the halt to these microbicide trials is disappointing, other products (‘Carraguard’, ‘Buffer gel’ and ‘Pro 2000’) are under trial in other parts of the world. All of them block HIV infection and have a similar presumed mechanism of action.

It is also important to study whether microbicides will be acceptable to women and their partners in our cultural setting. These behavioural studies are ongoing. The acceptability of Tenofovir gel is currently being assessed in women participating in the Phase II study and their husbands, as well as in other women not participating in the study and their husbands.

An ICMR task force has also been initiated to undertake multicentric cohort studies that could help create sites all over the country to undertake Phase II and III vaginal microbicide trials.

Female condoms
Another female-controlled method of HIV prevention is the female condom. Studies at NARI, Pune, and YRG Care, Chennai, have compared the acceptability of different types of female condoms (such as ‘Reddy’ and ‘Reality’). The Reddy female condom had a significantly better acceptability than the Reality condom among women who were less educated and who had not used male condoms before. However, participants were less confident about the Reddy condom for protecting them from HIV disease or pregnancy as compared to a male condom. An additional study has been planned to compare different shaft lengths of female condoms.

Studies on the acceptability of female condoms were conducted by Hindustan Latex Family Planning Promotion Trust, and Female Heath Foundation (UK), in collaboration with NACO, the state AIDS control societies and NGOs in Andhra Pradesh, Kerala and Maharashtra, among female sex workers, MSMs and married women. The study concluded that the female condom was both acceptable and feasible, but it would have to be advocated for, and women would have to be counselled and trained. Forty two per cent of the MSM in this study felt that the female condom gave them better protection than the male condom. The time and privacy required for its insertion and the feel was a major concern expressed by female sex workers in the study.

A vaccine against HIV
Since the beginning of the epidemic, a vaccine that would prevent a person exposed to HIV from infection has been considered to be the best long-term prevention option. The quest for the vaccine is one of the most difficult challenges faced by the scientific world today. It has resulted in many advances in the field of basic sciences as well as bioethics. The first vaccine went into clinical trials in 1987 but only one vaccine candidate completed Phase III trials – and the results were disappointing. However, there are many other promising vaccines in Phase II and later studies around the world.

In India, the first vaccine trial was initiated at NARI Pune, in 2005 and was completed in January 2007. This was a Phase I study of the Adeno Associated Virus (AAV) based HIV-1 subtype C vaccine. In this study, the safety and the ability of the vaccine to evoke an immune response (immunogenecity) were studied in healthy volunteers. The study sponsor, International AIDS Vaccine Initiative, also funded a second similar study using another, Modified Vaccine Ankara -based multivalent vaccine candidate which was developed by an ICMR scientist. This trial is being conducted at the Tuberculosis Research Centre, Chennai. Based on the evidence of safety and sub-optimal immunogenecity, the AAV-based vaccine candidate is being tested at higher dosages in South Africa and might be considered for further evaluation in a “prime-boost” concept: the use of a combination of two vaccine candidates to induce a better immune response.

There are many issues confronting HIV vaccine development: besides the availability of measures of protective immunity in volunteers, the genetic variation among HIV strains and diversity in geographical distribution necessitate a search for a broadly immunogenic vaccine.

The use of antiretroviral therapy to prevent HIV transmission has been one of the greatest success stories in HIV prevention in two settings: prevention of mother to child transmission (MTCT), and after workplace exposure for health care workers (post-exposure prophylaxis or PEP). The first has been studied in various clinical trials which have provided incontrovertible evidence that has been translated into programmes. Guidelines for the second have been obtained from evidence from smaller studies and reports and analysis of secondary data.

Prevention of mother to child transmission
The largest MTCT study in India was a feasibility study of AZT commissioned by NACO in 1999, conducted in 11 institutions in five high prevalence states. This found that 43.5% of pregnant women accepted AZT prophylaxis and 22% opted for breast-feeding at birth. This study not only provided data on prevalence of HIV, but also served to test the feasibility of voluntary counselling and testing and AZT intervention in the governmental health care delivery system.

Subsequently NACO undertook a feasibility study of single dose Nevirapine for MTCT. A collaborative study between Johns Hopkins University and B J Medical College, Pune, studied Nevirapine as an intervention in HIV infected pregnant mothers and babies. These studies have culminated in one of the world’s largest programmes for prevention of mother to child transmission of HIV in India.

In addition, antiretrovirals are also being developed as microbicides and are being studied in different parts of the world for pre-exposure and post-exposure prophylaxis.

Studies of sero-discordant couples
Studies in Africa have shown that HIV is more easily transmitted when there are high levels of HIV virus circulating in the infected person’s blood (HIV viral load) and in the genital secretions. ART could be used to reduce these levels. Research on discordant couples – with one positive and one negative sexual partner – can look at how ART and other drugs can prevent HIV infection. A randomised trial to evaluate the effectiveness of antiretroviral therapy to prevent the sexual transmission of HIV-1 in sero-discordant couples has begun at NARI, Pune, and YRG Care, Chennai. This study is also being conducted in other parts of the world like the African continent, Thailand and the USA.

Male circumcision
A number of epidemiological studies report an association between the lack of male circumcision and an increased risk of sexual transmission of HIV. They also show a low incidence of HIV in communities that traditionally practice male circumcision.

This was also reported from a prospective cohort study of 2,298 HIV-uninfected STD patients in Pune. Circumcision was found to be strongly protective against HIV-1 infection but not against herpes simplex virus type 2, syphilis or gonorrhoea. The study emphasised that as the majority of the male population is uncircumcised, it is important to stress penile hygiene and condom use to prevent sexual transmission of HIV in India.

The recently published results of clinical trials in Africa show that male circumcision does reduce the risk of HIV infection. An ICMR task force reviewed the findings and has decided to initiate behavioural studies to guide decisions on the initiation and implementation of a prevention programme.

The way forward

There is a wide array of research activity on HIV in India. Trends in HIV prevalence in different subpopulations at risk, surveys in general populations and estimations at the local level need to be continued to assess the progress of the epidemic, inform policy makers and assess interventions. Various interventions for both prevention and treatment have been put in place and studies must assess these interventions. Operations research must be done on the implementation of various programmes. Basic research in viral pathogenesis, immunology and low-cost diagnostics will help drive advances in vaccine related research, therapeutics, microbicide development and the assessment of newer molecules for anti-HIV activity. These findings from the lab need to be translated to actual use.

Observational studies and clinical research will continue to contribute data to inform researchers and clinicians on the nature of the epidemic, especially with expanding access to first line antiretroviral therapy. Clinical trials on ART for treatment and prevention will provide valuable evidence to drive treatment and prevention guidelines. Clinical trials and feasibility studies for prevention options like vaccines and microbicides are ongoing. New trials with newer candidates need to be initiated in the quest for preventive options.

There is need to conduct multicentric trials in different parts of the country as we move into Phase II and III trials. Clinical research on optimal management of opportunistic infections is necessary. Studies on health care practices and the role of traditional and allopathic systems of health care in HIV management need to go hand in hand with other clinical research. The recent evidence regarding the protective effects of male circumcision needs to be studied in the context of the Indian epidemic and socio-cultural milieu.

Suggested reading

NARI: www.nari-icmr.res.in
NACO: www.nacoonline.org
CDC: www.cdc.gov
UNAIDS: www.unaids.org
Indian Journal of Medical Research: Special edition on HIV AIDS: http://www.icmr.nic.in/ijmr/2005/April/apr_contents.htm
Clinical care Options: http://www.clinicaloptions.com/HIV.aspx (useful for medical professionals)
AIDSmeds.com: http://www.aidsmeds.com/ (a site owned and operated by positive people, is easy to read and contains useful information on treatment, drugs, including drug interactions, news, community forums.
AVERT Society (HIV AIDS in India):http://www.avert.org/aidsindia.htm

(Sheela Godbole is senior research officer in the division of epidemiology and biostatistics at the National AIDS Research Institute, Pune. She works on clinical trials of antiretroviral drugs for the prevention and treatment of HIV/AIDS, disease burden estimates, surveillance and surveys. Sanjay Mehendale is deputy director (senior grade) and head of the division of epidemiology and biostatistics at the National AIDS Research Institute, Pune. He works on cohort studies, surveys, surveillance and clinical trials related to HIV/AIDS)

Infochange News & Features, February 2008