WASHINGTON, Jan 9: A joint study of the AIDS virus infecting patients in India by US and Indian researchers has revealed `new and unexpected difficulties' in developing an vaccine for India, Johns Hopkins University has said.Scientists at the university and in India say they have sequenced the complete genome of a form of HIV from India for the first time. They revealed unexpected variation in genes for one key part of the `virus, prompting the researchers to suggest that currently favoured approaches to vaccine development may not work.The study suggested that different forms of HIV in India, unlike the single US virus type, may be combining in a way that will further complicate vaccine development.The US arm of the study was directed by Hopkins virologist Stuart C Ray. Indian experts on the team were Kavita S Lole and Deepak Gadkari of the national institute of virology, Pune, and Smita S Kulkarni and Ramesh S Paranjape of the National Aids Research Institute, Pune.The university saidresearchers know that the genetic makeup of the virus varies with geography. They have catalogued ten possible different HIV subtypes, lettered A to J. ``India's strains are subtype C, a variety dominant in Africa and S-E Asia," Stuart Ray said. Knowing a subtype's makeup is an important step on the road to a vaccine.''During the study, funded by US national institutes of health grants and support from the Government of India, researchers drew blood samples from six newly infected Indian volunteers. The samples reflected HIV variation in India. The PCR technique to amplify the viral genes and their resulting analysis took place at Hopkins. The PCR is a new technique to allow taking of small quantities of DNA and amplifying it to make it easier to analyse.The scientists found that while the virus has much in common with subtype C samples worldwide, the genes coding for proteins in the outer `envelope' of the virus vary significantly from B, strains that form the backbone of vaccines in internationaltrials. ``It means we should expect problems with any vaccine based solely on envelope proteins,'' Ray said, adding ``we should probably look to other places in the virus for a vaccine.''
