Foot-and-mouth disease (FMD) is a highly dangerous, highly contagious viral disease of farmed and wild cloven-hoofed animals, characterized by a significant decrease in the performance of diseased animals and high mortality among young animals.
FMDV exists as seven immunologically distinct serotypes, O, A, C, Asia 1, SAT-1, SAT-2, SAT-3, with diversity of topotypes, genetic lineages and strains; the virus is highly variable and characterized by narrow specificity of immunity in animals. Currently FMDV type O of recently emerged sublineage O/ME-SA/Ind-2001 is globally spread.
The Russian Federation and Republic of Kazakhstan are not enzootic countries and they have FMD free zones, recognized by the WOAH. In the recent years, FMD sporadic cases have been reported in these countries, which are deemed to be associated with the virus transmission from infected domestic and wild cloven-hoofed animals from neighboring countries. In Mongolia FMD O/ME-SA/Ind-2001 was first identified in March 2015, and since then it has significantly spread across the country.
In 2021–2022, FMD outbreaks were reported in Mongolia, Kazakhstan and Russia that border the countries where the virus is actively circulating.
The phylogenetic analysis of VP1 genomic region, performed by the FGBI “ARRIAH” showed that FMDV detected in the tested samples belongs to ME-SA topotype (Near East – South Asia), genetic lineage O/ME-SA/Ind-2001. There was 1.0–3.8 % divergence in VP1 genomic region between the isolates from Russia, Kazakhstan and Mongolia. Mongolia isolates varied by 1.0–3.3% between themselves and Russian and Mongolian isolates varied just by 0.8%. Cambodian isolates of 2019 (MZ634454, MZ634455 and MZ634456) demonstrated the greatest similarity with the studied isolates from Russia Mongolia and Kazakhstan.
The results of the vaccine matching tests highlighted the need to pay attention to the antigenic matching of the vaccines used in the current epidemic situation. Due to insufficient antigenic relationship between FMDV isolates and production strains О1 Manisa (ME–SA), О No. 2102/Zabaikalsky /2010 (O/Mya-98) (r1 = 0.05–0.28) the most closely related strain О No. 2311/ Zabaikalsky /2016 (O/Ind-2001) (r1 = 1.0) should be used for preventive immunization.
The detection of genetic lineage O/ME-SA/Ind-2001 in Kazakhstan, Russia and Mongolia in 2021–2022 implies that panzootic is escalating and FMD is aggressively spreading to new territories towards north. The selection of a strain for the manufacture of vaccines effectively protecting animals becomes relevant in order to avoid the disease caused by the circulating O/ME-SA/Ind-2001e sublineage. Global spread of pandemic lineage O/ME-SA/Ind-2001 necessitates enhanced surveillance of FMD in order to timely develop FMD control and prevention strategy.