A Newly Emerging Serotype A Strain in Foot-and-Mouth Disease Virus with Higher Severity and Mortality in Buffalo than in Cattle Calves in North Egypt

SIMPLE SUMMARY: Foot-and-mouth disease virus (FMDV) is the etiologic agent of foot-and-mouth disease (FMD), which causes severe economic losses among cloven-hoofed animals in endemic nations. Egypt is a bridge for FMDV pools between continents, where three serotypes (A, O, and SAT2) have established an enzootic state. Recently, a severe FMD epidemic struck several farms in the Beheira province, north Egypt. This study was the first to detect the newly emerging FMDV, serotype A, Europe–South America (Euro–SA) topotype that was collected during such outbreaks in twenty calves’ tongue epithelial samples from five infected farms based on virus isolation, molecular methods, and phylogenetic analysis. Additionally, we found that this strain caused higher peracute mortalities in water buffalo (Bubalus bubalis) (25.7%; 95% CI: 13–43) than in cattle (8.6%; 95% CI: 2–24) calves. Meanwhile, in fatal cases, severe clinical signs such as dullness, hypothermia, bradycardia, and cardiac arrhythmia were common in both species. In conclusion, we first characterized the newly emerging FMDV in the calves of Beheira as more fatal and severe in buffalo than in cattle calves. ABSTRACT: A severe foot-and-mouth disease (FMD) epidemic struck several Egyptian provinces recently, causing significant losses among animals even in vaccinated farms. This study indicated the existence of the newly emerging foot-and-mouth disease virus (FMDV) and first investigated its effect on the Egyptian water buffalo (Bubalus bubalis) and cattle calves in the Beheira province, north Egypt. Twenty tongue epithelial samples from diseased calves in five infected farms were randomly collected, prepared, and propagated using baby hamster kidney-21 (BHK-21) cells. Whole genomic RNA was extracted from the cells of the third passage. A FMDV genome was detected and serotyped using one-step reverse transcription polymerase chain reactions (RT-PCRs). Nucleotide sequencing of the purified serotype-specific PCR bands was performed, and a maximum likelihood phylogenetic tree based on 600 base pairs of VP1 was constructed. The results identified FMDV, serotype A in all infected samples, whereas the serotypes O and SAT2 were negative. The obtained 20 sequences were identical to each other and similar to the newly reported strain in Egypt that belongs to the Europe–South America (Euro–SA) topotype. The epidemiological and clinical parameters associated with such a strain were fully recorded by veterinarians and analyzed in a single infected farm including 70 cattle and buffalo calves. It caused higher peracute mortalities in buffalo (25.7%; 95% CI: 13–43) than in cattle (8.6%; 95% CI: 2–24) calves. Severe clinical signs such as dullness, hypothermia, bradycardia, and cardiac arrhythmia were common to both except in fatal cases, whereas hyperthermia and respiratory signs were prevalent in cattle calves. In conclusion, we first characterized the newly emerging FMDV in the calves of Beheira as more fatal and severe in buffalo than in cattle calves.