Virological and molecular characterization of canine distemper virus passaged at high temperature towards development of thermostable vaccine candidate

Abstract

Thermolabile nature of viruses is a major problem faced by most live attenuated vaccines. Addressing this issue will help increase the success rate of vaccination and reduce the economic burden on vaccination campaigns. In current study, the Canine Distemper Virus (CDV) belonging to India-1/Asia-5 lineage was adapted to grow at 41.5oC for assessing its suitability as thermostable vaccine candidate. The growth kinetics of thermotolerent virus was compared to that of original parent virus and it was found that the thermotolerent virus could grow only to a lower titre (4.5 logTCID50 per ml) in Vero cells as compared to the parent virus (5.61 logTCID50 per ml). When the coding sequences of structural genes of the virus M, N, H and F were compared before and after the high temperature passage, it was found that the H gene accrued the highest number of changes as compared to other genes of CDV. The mapped mutations in DNA and substitutions in amino acid sequences may shed light on the structural and functional mechanisms of virus adaptation at high temperature to be used as a strategy for creating recombinant thermostable vaccines.