Division of Virology, Defence Research & Development Establishment, Gwalior-474002, India.
Chikungunya virus (CHIKV), a member of the Alphavirus genus, is of considerable public health importance in Southeast Asian and African countries. CHIK virus outbreak of unprecedented magnitude has swept the Indian Ocean territories principally involving Re´ union Island, Comoros, Mauritius, Seychelles and Southwestern India. The epidemic was a surprise because of its unexpected emergence, its unprecedented magnitude, explosive spread and clinical severity that was rarely or never observed before. There is neither effective vaccine nor suitable drugs available to combat the Chikungunya virus infection. Developing an effective purified inactivated vaccine against CHIKV can provide the best means to control the disease. In the present study, attempts were made to prepare a Vero cell adapted purified formalin inactivated prototype vaccine candidate by using, an Indian strain of CHIKV (ISWHYd DRDE- 06) isolated from Hyderabad, India. The bulk preparation of the candidate virus was undertaken in micro carrier based spinner culture using cytodex-1 in virus production serum free medium (VP-SFM, In-vitrogen, USA). The virus preparation was concentrated by PEG precipitation, purified by sucrose gradient and inactivated using standard formalin inactivation protocols. The inactivated vaccine was formulated with Aluminum hydroxide and administered to mice by subcutaneous inoculations. The immunized mice were tested for humoral immune response by plaque reduction neutralization test, micro cytotoxicity assay and ELISA. The antibody titre of the post vaccinated sera was found to be 1:6400 by ELISA. In addition, the vaccinated mice developed a very high titer (PRNT 90 – 1: 1600) neutralizing antibodies.
This finding suggests that the prototype vaccine candidate used in this study has potential to neutralize the virus infectivity. Further assessment of safety, potency and CMI response is in progress.
