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[NEW DELHI] Indian scientists have found new strains of the HIV1-C subtype – which is responsible for half of the world’s HIV infections – are evolving rapidly in this country.

The proportion of some of these new strains of the HIV1-C went up from two per cent in 2000–2003 to 30 per cent a decade later, said their study, published in the Journal of Biological Chemistry this month (6 November). The HIV1-C accounts for more than 95 per cent of infections in India.

This is for the first time that scientists have shown that HIV1-C, considered stable since its detection in early 1980s, is evolving.

The scientists, led by Udaykumar Ranga, professor of molecular biology and genetics at the Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore, have identified five different strains of HIV1-C. Of these, one strain was found to be more infectious than others.

For their study, the scientists used blood samples collected from diverse hospitals and research institutes in Bangalore, Chennai and New Delhi.

What helps the HIV virus infect human beings is a protein called NF-kappaB. While other HIV strains have one or two copies of NF-kappaB, the conventional HIV1-C subtype has three copies, which explains its higher prevalence all over the world. 

Significantly, the JNCASR scientists found the more infectious of the new strains to have as many as four copies of NF-kappaB – though they were not more virulent than the original strain. "Our data do not suggest that the new viruses promote faster disease progression to AIDS," Ranga told SciDev.Net.

According to Ranga, no change in disease management strategy is indicated. "The old and new viruses share the same reverse transcriptase gene, hence, the new viral strains must be as sensitive to anti-retroviral therapy as the old viral strains are." 

Retroviruses reproduce by transcribing their ribonucleic acid (RNA) into deoxyribonucleic acid (DNA),   using the reverse transcriptase enzyme. The resultant DNA inserts itself into host cell DNA and is reproduced along with the cell and its daughters.

Shahid Jameel, group leader for virology, International Centre for Genetic Engineering and Biotechnology, New Delhi, said that the molecular features of their genome do make HIV viruses replicate better, leading to greater transmission.

"But then, now there is more awareness and better anti-HIV drug availability that will counter increased transmission potential," Jameel told SciDev.Net.   

Link to abstract in Journal of Biological Chemistry: