doi:10.1038/nindia.2008.173 Published online 31 March 2008
Scientists have identified most of the India-specific genome variants of the cervical cancer causing Human Papillomavirus (HPV) type 16, giving vaccine makers a precise tool to make second generation vaccines that can drastically reduce Indian incidence of the cancer.
A major inter-institutional study has identified India-specific HPV genome variants which can be used to develop DNA–based vaccines that are cheaper, easy to store and transport and do not require cold chain facility. The HPV type 16 variety assumes importance since it is responsible for more than 80 per cent of cervical cancer cases, the most frequent gynecological malignancy and a leading cause of cancer deaths in India.
At present, two protein–based vaccines developed in U.S.A. are being put on clinical trials in preadolescent-girls. "To develop an immunogenic and tolerable vaccine against HPVs that cause cervical cancer in India, it was important that a vaccine be made specifically for HPV genome variants prevalent in India," says one of the lead researchers Bhudev Das.
In India, two prophylactic vaccines having HPV virus like particles containing capsid L1 protein are undergoing clinical trials. The team analyzed sequence variations in two cancer causing genes of HPV — E6, E7 as also the L1 gene of major capsid protein and the long control region (LCR). They identified quite a few frequently occurring variations, T350G (100%), T789C (87.5%), A6695C (54.5%) and G7521A (91.1%) and one novel variant in E6 and 4 in L1 and LCR each, which they designated as Indian variant.
The study also showed that HPVs found in India are of European lineage. "HPV 16 variant assay can also be employed for large scale epidemiological study to differentiate intergene sequence variations," Das says.