Key result
In a vaccinated cattle herd, 24% of animals with clinical signs tested positive for FMDV serotype O, which was genetically distinct from the administered vaccine strain.
Observational (n=77)
An FMDV outbreak in vaccinated cattle in Saudi Arabia was caused by a serotype O strain genetically distinct from the administered vaccine strain.
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Vaccine mismatch may underlie FMD outbreaks in cattle; leaves open needs for strain surveillance and updated vaccines.
BACKGROUND: Foot-and-mouth disease virus (FMDV) is a highly contagious viral infection of large ruminants. Despite the massive application of vaccines against FMDV, several outbreaks are still being reported in Africa and Asia. AIM: To perform molecular characterization of FMDV in an outbreak among a cattle herd Saudi Arabia in 2016. This herd had been vaccinated with a polyvalent FMDV vaccine. METHODS: To investigate this outbreak, we collected specimens from 77 animals showing typical clinical signs of FMDV. Specimens including sera, nasal swabs, and tissues (tongue, coronary bands, hooves, and hearts) were collected. We tested the collected cattle sera for the presence of FMDV antibodies with commercial ELISA kits. In addition, we tested the swabs for the presence of the most common FMDV strains (O, A, Asia-1 and SAT-2) with RT-PCR using serotype-specific oligonucleotides. RESULTS: Serology showed that 22% of the tested sera were positive. Molecular testing of the examined swabs confirmed that 24% of the tested animals were positive. Our sequencing analysis confirmed that the circulating strains of FMDV belonged to FMDV serotype O. The phylogenetic tree based on the FMDV-VP-1 gene revealed high nucleotide identity between the circulating strains and the Bangladesh strain (99%). These strains were distinct (shared 89% nucleotide identity) from the FMDV-O strains used for the preparation of the vaccine administered to the animals in this herd. Moreover, they had 7% nucleotide difference between the FMDV-O strains reported in Saudi Arabian in 2013. CONCLUSION: More in-depth molecular characterization of these FMDV strains is warranted.
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EL-Ghareeb et al. (2018) conducted an observational in Foot-and-mouth disease virus (FMDV) (n=77). FMDV infection was evaluated on FMDV positivity by RT-PCR. In a vaccinated cattle herd, 24% of animals with clinical signs tested positive for FMDV serotype O, which was genetically distinct from the administered vaccine strain.
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