Characterization of Foot and Mouth Disease Virus Serotype SAT-2 in Swamp Water Buffaloes (Bubalus bubalis) under the Egyptian Smallholder Production System

Abstract

Spontaneous mutations are a common characteristic of the foot and mouth disease virus (FMDV), leading to wide antigenic variations resulting in the emergence of new topotypes and lineages of FMDV, which contributes to occasional vaccination failures. The objectives of the present study were to genetically characterize FMDV isolated from water buffaloes and study the biochemical and histopathological indicators of infected animals. Fifty-four water buffaloes of both sexes and different ages suffered from acute symptoms of FMD were clinically examined and randomly selected for inclusion in this study. Oral desquamated epithelial and oropharyngeal fluid samples have been tested for FMDV by reverse transcriptase PCR (RT-PCR). Tissue and serum samples were also collected from the diseased buffaloes and subjected to histopathological and biochemical analysis. Our findings showed that all examined samples were confirmed to be positive to FMDV serotype SAT-2 and were adjusted to be responsible for the recent disease outbreak in this study. Phylogenetic analysis revealed that the circulating viruses were of the SAT-2 serotype, closely related to the lineage of lib12, topotype VII, with 98.9% identity. The new lineage of SAT-2 showed a high virulence resulting in the deaths of water buffaloes due to heart failure, confirmed by high serum levels of inflammatory and cardiac markers, including haptoglobin, ceruloplasmin, cardiac troponin I and creatine phosphokinase-MB, indicating an unfavorable FMD-infection prognosis. In conclusion, we document the presence of new incursions circulating in water buffalo populations in Egypt in early 2019, explaining the high morbidity rate of FMD outbreak in early 2019. Furthermore, the newly identified serotype SAT-2 lib12 lineage, topotype VII, showed an aggressive pattern in water buffaloes of the smallholder production system.

Viral dynamics and immune responses to foot-and-mouth disease virus in African buffalo (Syncerus caffer)

“…Altogether, these results demonstrated similar dynamics of FMDV infection and immune responses after needle infection or direct in-contact challenge in African buffaloes compared to cattle, despite marked differences in the clinical outcome [ 5 , 20 ]. Also, similar transmission, viral dynamics and neutralizing antibody responses have been described for FMDV infected water buffalo ( Bubalus bubalis ), a domestic buffalo commonly farmed in Asia; however, water buffalo showed foot and mouth vesicles, like cattle [ 51 – 53 ]. The reasons for the different clinical outcomes between the host species remains unclear, in addition to the lack of understanding of the mechanisms responsible for the tissue distribution of FMD vesicles in cattle [ 54 ].…”

Environmental Streptococcus uberis Associated with Clinical Mastitis in Dairy Cows: Virulence Traits, Antimicrobial and Biocide Resistance, and Epidemiological Typing

“…S. uberis is a well-known pathogen that causes bovine intramammary infections worldwide. Nonetheless, there are scant epidemiological data on S. uberis isolated from lactating cows in Egypt, especially in the smallholder production system, despite the fact that this extensive system type is the most common traditional livestock farming system among Egyptian farmers [49,50].…”

Evolutionary Dynamics of Foot and Mouth Disease Virus Serotype A and Its Endemic Sub-Lineage A/ASIA/Iran-05/SIS-13 in Pakistan

“…Sporadic diversification is a preferred method of evolution for many positive and negative single-stranded RNA viruses, which usually exhibit purifying selection acting on their genome due to their small sizes [ 12 ]. Genetic drift and spontaneous mutations are reported to be responsible for the antigenic change in FMDV [ 17 , 52 ]. The sporadic diversifying evolution is calculated using the dN/dS ratio, which has a risk of overestimation due to non-fixed mutations in the population.…”

“…The virulence and transmissibility of co-circulating viral strains in diverse and susceptible hosts lead to flux in the virus population over time [ 15 ]. This leads to the emergence and establishment of new variants that can compromise vaccine efficacy and have direct implications for disease control through preventive vaccination [ 16 , 17 ].…”

“…A major challenge for such units is sustainable and efficient farm management. A failure of management can lead to the emergence and subsequent spread of new and possibly more infectious variants of FMDV in an area [ 17 , 20 ]. Serotype A is included in all seven endemic pools of FMD, except pool 6, and is differentiated into three topotypes: ASIA, AFRICA, and EURO-SA.…”