Characterisation of recent foot-and-mouth disease viruses from African buffalo (Syncerus caffer) and cattle in Kenya is consistent with independent virus populations

Abstract

BackgroundUnderstanding the epidemiology of foot-and-mouth disease (FMD), including roles played by different hosts, is essential for improving disease control. The African buffalo (Syncerus caffer) is a reservoir for the SAT serotypes of FMD virus (FMDV). Large buffalo populations commonly intermingle with livestock in Kenya, yet earlier studies have focused on FMD in the domestic livestock, hence the contribution of buffalo to disease in livestock is largely unknown. This study analysed 47 epithelia collected from FMD outbreaks in Kenyan cattle between 2008 and 2012, and 102 probang and serum samples collected from buffalo in three different Kenyan ecosystems; Maasai-Mara (MME) (n = 40), Tsavo (TSE) (n = 33), and Meru (ME) (n = 29).ResultsAntibodies against FMDV non-structural proteins were found in 65 of 102 (64%) sera from buffalo with 44/102 and 53/102 also having neutralising antibodies directed against FMDV SAT 1 and SAT 2, respectively. FMDV RNA was detected in 42% of the buffalo probang samples by RT-qPCR (Cycle Threshold (Ct) ≤32). Two buffalo probang samples were positive by VI and were identified as FMDV SAT 1 and SAT 2 by Ag-ELISA, while the latter assay detected serotypes O (1), A (20), SAT 1 (7) and SAT 2 (19) in the 47 cattle epithelia. VP1 coding sequences were generated for two buffalo and 21 cattle samples. Phylogenetic analyses revealed SAT 1 and SAT 2 virus lineages within buffalo that were distinct from those detected in cattle.ConclusionsWe found that FMDV serotypes O, A, SAT 1 and SAT 2 were circulating among cattle in Kenya and cause disease, but only SAT 1 and SAT 2 viruses were successfully isolated from clinically normal buffalo. The buffalo isolates were genetically distinct from isolates obtained from cattle. Control efforts should focus primarily on reducing FMDV circulation among livestock and limiting interaction with buffalo. Comprehensive studies incorporating additional buffalo viruses are recommended.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-015-0333-9) contains supplementary material, which is available to authorized users.

The role of African buffalo in the epidemiology of foot-and-mouth disease in sympatric cattle and buffalo populations in Kenya

“…FMDV can be divided into seven serotypes (O, A, C, SAT 1, SAT 2, SAT3, and Asia 1) (Kitching et al, 1989), with no cross-immunity between serotypes (Kitching et al, 1989). In Kenya, FMDV was first described in 1952, with serotypes O, A, SAT 1 and SAT 2 presently circulating in the country (Wekesa et al, 2015b) and generally in East Africa (FAO., 2016, Sangula et al, 2011. A Bayesian phylogenetic analysis of SAT1 serotypes from Kenya revealed two independent introductions from southern Africa (Sangula et al, 2010); with that buffalo are maintenance hosts for SAT serotypes of FMDV, and proximity to wildlife areas is a risk factor for clinical outbreaks in cattle in East Africa (Ayebazibwe et al, 2010a).…”

“…Furthermore, buffalo in South Africa are largely separated from cattle by fencing (Dion et al, 2011, Miguel et al, 2013, which is in stark contrast to the extensive wildlife-livestock sympatry observed in semi-arid pastoralist rangelands in East Africa. Only SAT1 and 2 serotypes have been isolated from buffalo in Kenya, and the single sequences available each for buffalo-origin SAT1 and SAT2 viruses are genetically distinct from those in livestock, leading to the theory of independent virus populations in East African buffalo and cattle (Wekesa et al, 2015b). However, more genetic data on sequences found in buffalo are needed to elucidate the molecular epidemiology of FMDV in East African wildlife-livestock interfaces and the phylogenetic relationship between buffalo-derived viruses and vaccine strains.…”

Generation of mAbs to foot–and–mouth disease virus serotype A and application in a competitive ELISA for serodiagnosis

“…Hedger et al [27] found that animals undergoing natural infection with one type of FMDV (type O) had equal or even higher serum antibody titres against one or more of the other types tested (types A, C, Asia 1 and SAT 1). Thus, it remains unclear whether the cross-reactivity among serotypes is caused by low assay specificity, or heterotypic humoral responses following virus infections [28]. Though cross–reactivity among FMDV serotypes is undesirable, it is preferable when sensitivity is the aim.…”

Global Foot-and-Mouth Disease Research Update and Gap Analysis: 7 - Pathogenesis and Molecular Biology

“…Several studies of FMDV phylogenetics have been published in the past 5 years (Ahmed et al, 2012;Gorna et al, 2014;Kasanga et al, 2015;Parthiban et al, 2015b;Subramaniam et al, 2015;Wekesa et al, 2015;Zhang et al, 2015). At a basic level, these studies can identify related outbreaks and should form part of routine surveillance; they may also indicate the extent of relatedness between vaccine and field strains.…”