Researchers in India studied the HIV-1 subtype C tat gene found in their country. They found it was most similar to other subtype C tat genes. They created a consensus sequence from Indian samples and optimized it for use in a vaccine. Mice immunized with the tat DNA vaccine alone developed cross-clade immune responses. Those given both DNA and MVA vaccines saw their immune responses increase 3-fold. Key immunogenic regions on the Indian subtype C Tat protein were identified as amino acids 1-20, 16-35, 31-50, and 67-86, with the 31-50 region found to be most immunodominant. The study suggests the Indian subtype C tat gene is a good candidate for inclusion