Background:
Owing to very high genetic and antigenic diversity, one strain of Foot-and-Mouth (FMD) virus often fails to confer protection against others within a serotype. Therefore, high antigenic relatedness of contemporary field strains with the vaccine strains holds the key to the success of the FMD vaccination programme, and FMD vaccine should incorporate strains that cover existing field viruses. Of the three serotypes endemic to India, serotype A is antigenically and genetically the most heterogenous in nature. FMD virus serotype A field strains antigenically divergent to the in-use vaccine strain (A IND 40/2000) which do not match to provide sufficient protection against viruses which have been circulating in India since 2012-13 determined by vaccine matching studies. Therefore, warranted the selection of new candidate vaccine strain to cover this diversity in the antigenic spectrum. The change in virus strain will allow coverage against protection of most of the field viruses circulating in the country:
Technology Details:
A new vaccine strain namely “A IND 27/2011” has been identified by ICAR-NIFMD as a suitable vaccine strain (in place of the in-use A IND 40/2000) considering its close antigenic relatedness with the contemporary field strains circulating in our country based on the vaccine matching studies conducted. The complete genome sequence of the new vaccine strain A IND 27/2011 has been generated and analysed. In addition, vaccine-worth quality attributes of the new candidate strain including the potency as an inactivated vaccine in cattle were also studied. The strain suited well with traits required by a vaccine in terms of its adaptability to adherent and suspension cell line, inactivation kinetics, its immunogenicity, and potency as an inactivated vaccine formulation in cattle. Change of vaccine strain becomes important again as the in-use A IND 40/2000 vaccine strain does not induce protection to the current circulating field viruses, based on the vaccine-matching studies conducted by ICAR-NIFMD.