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ShareBanglore: In what is considered to be a first-of-its-kind study from India, scientists from the Bangalore-based Jawaharlal Nehru Centre for Advanced Scientific Research have identified a potential candidate for developing a vaccine for Acquired Immuno Deficiency Syndrome (AIDS).
It is an exclusive study done on the Indian population infected with HIV, C-type virus. The C-type virus is also found in South Africa, China and other countries and accounts for nearly 56% of the patients suffering from HIV globally.
"In this study, we have identified a new epitope which when used in vaccines might provide protection against the progression of the disease," said Udaykumar Ranga, a faculty member of Molecular Biology and Genetics Unit at JNCASR. The discovery paves way for vaccine design to tackle HIV infection at an early stage, he added.
The cross-sectional study was conducted on 447 infected individuals and 150 healthy people. All of them were tested for antibody responses to Tat protein. Sixty-three individuals harboured antibodies to Tat which corresponds to 14 per cent of the study group. Of these 63, around 31 samples demonstrated a strong response. "While a majority of the study group showed low response to Tat, a small but significant part of infected group responded strongly to the protein. This suggests that we could design a vaccine based on this protein," said the main author, Venkatesh Kashi, a researcher at JNCASR.
"Neutralising Tat by antibodies might play an important role as Tat is released from the infected cells and this extra-cellular Tat exerts its pathogenic effects in many ways. However, no studies evaluating immune response to Tat have been carried out in India, which has the second largest number of HIV positive individuals in the world," Ranga explained.
Hence the researchers initiated the study by obtaining samples from Tuberculosis Research Centre in Chennai and Seva Free Clinic in Bangalore. "We have drawn a large number of samples and carried out a cross-sectional study. Since Tat is an early protein in the viral life cycle, mounting an attack on this protein is important," Kashi said.
During the experiment, the scientists identified that a class of antibodies called IgG1 was abundant in individuals demonstrating high immune response to Tat. "Presence of IgG1 reacting to Tat is indicative of not only strong antibody response, but also cell-mediated T-helper response." informed Ranga. He also explained that T-helper response is known to play a key role in eliciting a strong antibody response.
They further identified the region of Tat against which the antibodies were directed. "Using small pieces of Tat protein, we identified that the IgG1 antibodies were mainly directed at the cysteine-rich domain (CRD)" Kashi said.
