Scientists at the National Institute of Virology in Pune have found a genetic variant of the existing dengue virus in Tamil Nadu. According to the World Health Organization, the dengue virus (DEN) comprises four distinct serotypes (DEN-1, DEN-2, DEN-3 and DEN-4). Distinct genotypes (genetic structures) have been identified within each serotype.

The National Institute of Virology, which is the apex body for virology research in the country under the Indian Council of Medical Research, routinely tests samples of dengue virus to identify the strain circulating in different parts of the country. The scientists also look for any genetic variation in the known dengue serotypes.

During this study, the scientists found that the Asian (GI) genotype of DENV-1 had entered India from Singapore. “The Asian genotype was responsible for epidemics in Singapore during 2005 and in Sri Lanka during 2009,” Devendra Mourya, director of National Institute of Virology in Pune, told The Times of India. “This genotype was not found earlier in India. It is a new entrant to India.”

Testing samples of the dengue virus helps predict the severity of the infection in the community. Clinicians say that the severity of the symptoms associated with the dengue virus infection are related to the serotype of the virus in circulation. In India, the African-American genotype of the dengue virus is widely circulated.

Mourya told the newspaper the scientists at NIV have not tested all the samples, so it is difficult to say whether the Asian genotype has replaced the earlier genotype of the virus. While samples of dengue-positive patients from Tamil Nadu and Kerala were found to be infected with the Asian genotype, the samples from Maharashtra and Delhi did not find the presence of the new variant.

This identification of the Asian variant requires further study to understand its role in the recurrent dengue outbreaks in the country, so it is too early to say the Asian genotype has replaced the African-American genotype.

“The study proves how movement of DENV (dengue virus) can affect dengue outbreaks,” researchers wrote in the study published a peer reviewed journal named Virology.