Abstract

MS, Abousenna. Emergency evaluation for existing vaccine against recently isolated Foot and mouth disease virus type SAT2 in Egypt 2018. Vaccimonitor [online]. 2022, vol.31, n.1, pp. 9-14.  Epub Feb 01, 2022. ISSN 1025-0298.

Foot and mouth disease virus is a highly infectious and contagious pathogen. Recently the topotype VII, Lib‐12 lineage of serotype SAT2 was reported through outbreaks in Egypt during 2018. Vaccination is an effective way to control and combat the foot and mouth disease virus outbreaks especially in endemic areas like Egypt. The present study was aimed to evaluate the efficacy of the current produced foot and mouth disease vaccine, against the recently isolated field strain foot and mouth disease virus SAT2 topotype VII, Lib-12 lineage (SAT2 Libya), by applying in vitro and in vivo studies. Two batches of the current foot and mouth disease virus vaccine were inoculated in calves. At the 28th day post-vaccination serum samples were collected and tested against tissue culture adapted foot and mouth disease virus SAT2 Libya and SAT2/EGY/2/2012 using virus neutralization test to determine serological relationship (r1-value). The challenge test for vaccinated calves was carried out against the virulent foot and mouth disease virus SAT2 Libya. It was found that neutralizing antibody titers induced by the two vaccine batches (1 and 2) and those in unvaccinated animals were 0.48, 0.39 and 0.15 log10 TCID50/mL, respectively, while the challenge revealed protection values of 20%, 0% and 0%, respectively. Furthermore, the r1 values were 0.195 and 0.186 for vaccine batches (1 and 2), respectively. It was concluded that the available local commercial inactivated foot and mouth disease virus vaccine batches (SAT2 SAT2/EGY/2/2012) are unable to protect calves against the current circulating foot and mouth disease virus field isolate SAT2 topotype VII, Lib-12 lineage, thus it is highly recommended to update the existing vaccines with the present isolated strain.

Keywords : Foot-and-Mouth Disease; vaccine potency; livestock; serogroup.

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