Scientists a step closer to finding HIV vaccine

Developing an effective vaccine against HIV remains a challenge to date. Indian scientists have identified a new antibody against HIV subtype-C from Indian patients. This finding will help design vaccines against HIV in the future. When given with retroviral drugs, it will reduce HIV virus load in patients. This will also help in passive immunotherapy, which is killing low amounts of virus in patients who have accidentally been infected with the virus.

HIV-1 virus that causes AIDS has three subtypes A, B, and C, based on its genetic sequence. HIV subtype-C affects more than 50% of the patients globally and more than 90% patients in India and South Africa. Making a vaccine against HIV remains a challenge because the virus changes its proteins vey rapidly in the body. The immune system is unable to cope up and the virus is able to spread rapidly.

The immune system is constantly fighting under an HIV infection. HIV infection in the body elicits a natural immune response, where cells in the blood make antibodies against HIV. These antibodies bind to HIV, which marks it as a target for killing. The problem is that the immune system takes 3 to 4 years to develop effective antibodies against HIV. By this time, the numbers of immune cells reduce and the virus is already well spread in the body.

Now, scientists have identified a small antibody against HIV and named it C11. Since, this antibody is against the HIV virus subtype-C, it is particularly relevant for India.

Since a very long time scientists have been studying antibodies from patient samples to understand the proteins of HIV to design a good vaccine. A good vaccine is one that can generate effective antibodies against HIV.

Scientists at AIIMS in New Delhi have taken a step further in this direction. They collaborated with those at Indian Institute of Science in Bangalore, Translational Health Science and Technology Institute in Haryana, YR Gaitonde Centre for AIDS Research and Education in Chennai, National Brain Research Centre in Haryana, and International AIDS Vaccine initiative in USA. The study was funded by the Indo-South Africa project of the Department of Science and Technology, India.  

They took blood cells from six patients of HIV who visited AIIMS, New Delhi and YR Gaitonde Centre for AIDS Research and Education, Chennai, for treatment. The blood samples were used to make a library of all virus-specific DNA sequences in the patient body.  Then some of these DNA sequences were used to make proteins that could bind to HIV virus. These proteins were small antibody fragments that could bind to HIV virus with high efficiency. 

Smaller fragments of antibodies could bind to the HIV proteins more effectively than full antibodies because they could reach to smaller and deeper areas in the cells for binding. These proteins can also be used for targeted drug delivery to HIV-infected cells in the future.

The new antibody C11 binds to the virus subtype-C. In other parts of the world, antibodies against subtype-A and B have been identified earlier. This is the first study that identifies an antibody against the virus subtype-C in India. “In the future, this can be used to design a vaccine that elicits a good antibody response. So far not much work has been done on isolating broad neutralizing antibodies against subtype-C infected patients, and India needs special attention to make antibodies for subtype-C virus”, say scientists.

C11 that binds to HIV with high efficiency will serve two main purposes. It will be used in passive immunotherapy and in designing vaccines against HIV.

Passive immunotherapy is useful in preventing HIV infection and in reducing virus numbers. Antibodies kill very low amounts of HIV virus in patients who have accidentally got pricked. In this manner, it prevents HIV infection. HIV patients with weak immunity are given antibodies that bind to HIV in the patient’s body thereby reducing virus load, which helps to slow down or block the spread of HIV.

Antibodies that bind to broad types of HIV proteins can be used to identify proteins for making anti-HIV vaccines in the future.  “We have successfully generated human anti-HIV cross neutralizing antibody fragments with distinct specificities from Indian infected donors that can serve as potential reagents for blocking HIV infection and designing effective vaccines in the future”, say scientists.

The research team included Lubina Khan, Rajesh Kumar, Ramachandran Thiruvengadam, Hilal Ahmad Parray, Muzamil Ashraf Makhdoomi, Sanjeev Kumar, Heena Aggarwal, Madhav Mohata, Abdul Wahid Hussain, Raksha Das, Raghavan Varadarajan, Jayanta Bhattacharya, Madhu Vajpayee, K. G. Murugavel, Suniti Solomon, Subrata Sinha, and Kalpana Luthra. 

This story was published by Biospectrum, Health Analytics India and IndiaScience Wire. 

Reference: Scientific Reports 7: 45163.