The aim of this study was to characterize foot-and-mouth disease (FMD) viruses collected between 2004 and 2008 from Sudan, a country where FMD is endemic. Using virus isolation and antigen ELISA, three FMD virus serotypes (O, A and SAT2) were detected in 24 samples that were submitted to the FAO World Reference Laboratory for FMD. Pan-serotypic real-time RT-PCR assays targeting the 5' untranslated region (5'UTR) and 3D genes of FMD virus were also used to contribute to the laboratory diagnosis of these cases. The lack of concordant results between the real-time RT-PCR assays for three serotype O viruses was attributed to four nucleotide mismatches in the 5'UTR PCR primer and probe sites (three substitutions for the sense-primer and one in the TaqMan(®) probe region). Taken together, the laboratory results showed that recent FMD outbreaks that occurred during 2008 in northern and central Sudan were caused by serotypes O and SAT2, while serotype A was last detected in 2006. Phylogenetic analyses of VP1 sequences from these viruses were used to determine the relationships with 23 older viruses from Sudan and other viruses from West and East Africa. For serotype O, closest genetic identities were between concurrent and historical Sudanese isolates, indicating that within-country circulation is an important mechanism by which FMD is maintained year-on-year in Sudan. A similar pattern was also evident for serotype A and SAT2 viruses; however, these lineages also contained recent representative FMD viral isolates from other countries in the region suggesting that long-distance animal movement can also contribute to FMD dispersal across sub-Saharan Africa. These findings provide the first molecular description of FMD viruses that are circulating in Sudan, and highlight that further sampling of representative viruses from the region is required before the complex epidemiology of FMD in sub-Saharan Africa can be fully understood.

Laboratory animal models have provided valuable insight into foot-and-mouth disease virus (FMDV) pathogenesis in epidemiologically important target species. While not perfect, these models have delivered an accelerated time frame to characterize the immune responses in natural hosts and a platform to evaluate therapeutics and vaccine candidates at a reduced cost. Further expansion of these models in mice has allowed access to genetic mutations not available for target species, providing a powerful and versatile experimental system to interrogate the immune response to FMDV and to target more expensive studies in natural hosts. The purpose of this review is to describe commonly used FMDV infection models in laboratory animals and to cite examples of when these models have failed or successfully provided insight relevant for target species, with an emphasis on natural and vaccine-induced immunity. IntroductionFoot-and-mouth disease virus (FMDV: family Picornaviridae; genus Aphthovirus) is known to naturally infect a wide variety of cloven-hoofed domesticated and wild animal species, causing an acute disease characterized by vesicular lesions of the tongue, snout, buccal cavity, feet and teats (Grubman & Baxt, 2004). Despite causing extensive lesions, the cycle of infection in the individual animal is short, and foot-and-mouth disease (FMD) usually resolves without the need for treatment and is seldom lethal in adults (Arzt et al., 2011b). However, the highly contagious nature, wide dissemination and significant economic impact of FMD have made it one of the most feared livestock diseases and a major research focus for more than a century. Progress towards the development of effective tools for FMD control has been hampered by several factors including the cost and logistics of largeanimal experimentation in specialized high-containment facilities, incomplete knowledge of the host's immune systems and lack of immunological reagents compared to biomedical rodent species and humans. These factors delayed the production of vaccines on an industrial scale and this major research goal was subsequently only achieved in the 1950s (Lombard et al., 2007). In a review, Brown (2003) highlighted that this milestone could not have been achieved without certain significant advances in our knowledge of FMD. The first significant advance was the demonstration by Loeffler & Frosch (1897) that the disease was caused by a virus and the second was the establishment of FMD laboratory animal models, including the guinea-pig model (Waldman & Pape, 1920) followed by the suckling mouse model (Skinner, 1951). Although not without their flaws, these FMD laboratory animal models have helped elucidate several mechanisms of FMD pathogenesis, which would have been difficult to achieve directly in target species. These models have provided an accelerated time frame at significantly reduced costs to develop and test vaccine candidates and continue to be a useful tool for interrogating FMDV immune responses. However, we now know that porcine and ru...

Foot‐and‐mouth disease (FMD) is widely distributed in Sudan where outbreaks occur on an annual basis especially during the winter months (December‐February). This study aimed to increase our understanding of the epidemiological patterns of FMD in Sudan and connections to neighbouring countries by characterizing the genetic sequences of FMD viruses (FMDV) collected from samples collected in 10 Sudanese states over a 10‐year period (between 2009 and 2018). FMDV was detected in 91 of the 265 samples using an antigen‐detection ELISA. Three serotypes were detected: O (46.2%), A (34.0%), and SAT 2 (19.8%). Fifty‐two of these samples were submitted for sequence analyses, generating sequences that were characterized as belonging to O/EA‐3 (n = 17), A/AFRICA/G‐IV (n = 23) and SAT 2/VII/Alx‐12 (n = 12) viral lineages. Phylogenetic analyses provided evidence that FMDV lineages were maintained within Sudan, and also highlighted epidemiological connections to FMD outbreaks reported in neighbouring countries in East and North Africa (such as Ethiopia and Egypt). This study motivates continued FMD surveillance in Sudan to monitor the circulating viral lineages and broader initiatives to improve our understanding of the epidemiological risks in the region.

Foot-and-mouth disease (FMD) is widely distributed in Sudan where outbreaks occur on an annual basis especially during the winter months (December-February). This study aimed to increase our understanding of the epidemiological patterns of FMD in Sudan and connections to neighbouring countries by characterising the genetic sequences of FMD viruses (FMDV) collected from seven Sudanese states over a 10-year period (between 2009 and 2018). FMDV was detected in 91 of the 265 samples using an antigen-detection ELISA. Three serotypes were detected: O (46.2%), A (34.1%), and SAT 2 (19.8%). Fifty-three of these samples were submitted for sequence analyses, generating sequences that were characterised as belonging to O/EA-3 (n=18), A/AFRICA/G-IV (n=23) and SAT 2/VII/Alx-12 (n=12) viral lineages. Phylogenetic analyses provided evidence that FMDV lineages were maintained within Sudan, and also highlighted epidemiological connections to FMD outbreaks reported in neighbouring countries in East and North Africa (such as Ethiopia and Egypt). This study motivates continued FMD surveillance in Sudan to monitor the circulating viral lineages and broader initiatives to improve our understanding of the epidemiological risks in the region.