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

Q: What is the clinical evidence from this study?

Study design: Cross-Sectional. Population: Acute foot and mouth disease (FMD) in domestic Nile water buffaloes (Bubalus bubalis) (n=54). Intervention: Foot and mouth disease virus (FMDV) serotype SAT-2 (topotype VII, lib12 lineage) infection vs. Standard reference ranges and previously isolated/vaccine FMDV strains. Primary outcome: FMDV serotype SAT-2 positivity by RT-PCR and adult buffalo mortality due to heart failure/myocarditis (p=≤0.05).

Q: What does this research mean for the field?

A virulent foot-and-mouth disease virus serotype SAT-2 (topotype VII, lib12 lineage) caused the early 2019 outbreak in Egyptian water buffaloes, inducing severe myocarditis, elevated cardiac biomarkers, and heart failure mortality. Novelty: ClaimNovelty.CONFIRMATORY. Consensus alignment: ConsensusAlignment.NEUTRAL.

Hend M. El Damaty; Elshaima Fawzi; Ahmed N. F. Neamat‐Allah; Ibrahim Elsohaby; Abdelmonem Abdallah; Gamelat K. Farag; Yousry A. El-Shazly; Yasser S. Mahmmod

doi:10.3390/ani11061697

June 7, 2021AnimalsOpen Access

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

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Key result

FMDV SAT-2 lineage causes fatal myocarditis with ~26% mortality in adult water buffaloes.

P≤0.05
n=54

Figures

Why the study?

Spontaneous mutations in the foot and mouth disease virus (FMDV) cause antigenic variations, emerging lineages, and occasional vaccination failures. This study aimed to genetically characterize FMDV isolated from vaccinated water buffaloes during an outbreak and evaluate the biochemical and histopathological indicators of infected animals.

Key Points

To genetically characterize foot and mouth disease virus isolated from clinically infected water buffaloes and evaluate the biochemical and histopathological indicators of myocardial damage.
Randomly selected 54 clinically affected water buffaloes (aged 2 months to 8 years; 40 females, 14 males) vaccinated with Tri-Aphthovac vaccine in Sharkia and Dakahlia Governorates, Egypt, in early 2019.
Collected oropharyngeal swabs and oral epithelia for reverse-transcription PCR (RT-PCR) and VP1-coding sequencing (n = 5), alongside serum testing for cardiac troponin I, CK-MB, haptoglobin, and ceruloplasmin.
Performed histopathological examination on ventricular heart tissue samples collected during post-mortem examination of seven deceased buffaloes displaying heart lesions.
All 54 samples tested positive for FMDV serotype SAT-2 and negative for serotypes A and O, with VP1-coding phylogenetic analysis showing 98.9% identity clustering within topotype VII, lib12 lineage.
Infected animals exhibited elevated serum markers of cardiac injury and inflammation: cTnI (0.61 ± 0.02 µg/L), CK-MB (263.73 ± 5.56 U/L), haptoglobin (0.493 ± 0.051 g/dL), and ceruloplasmin (17.72 ± 1.23 mg/dL).
Histopathology revealed serofibrinous pericarditis and non-suppurative myocarditis with myocardial degeneration, necrosis, and lymphocytic infiltration in deceased animals.

Study Design

Type

Cross-Sectional (n=54)

Multicenter

Yes

Structured PICO

P

Population

54 vaccinated smallholder domestic water buffaloes (Bubalus bubalis; 74.1% female, aged 2 months to 8 years) in Egypt presenting with acute clinical signs of foot and mouth disease in early 2019.

E

Exposure

Natural infection with foot and mouth disease virus (FMDV) serotype SAT-2, topotype VII, lib12 lineage, evaluated via RT-PCR, VP1-coding region sequencing (n=5), serum cardiac and inflammatory biomarker assays (n=54), and cardiac histopathology (n=7).

C

Comparator

Standard reference ranges for biochemical/cardiac markers and GenBank reference/vaccine FMDV strains (including SAT-2 EGY/3/2012 topotype VII, lineage Gharbia 12).

O

Outcome

Genetic characterization of circulating FMDV (RT-PCR positivity and VP1 phylogenetic identity) and virulence profile assessed by mortality, cardiac/inflammatory serum biomarkers (cTnI, CK-MB, haptoglobin, ceruloplasmin), and cardiac histopathology.surrogate

Main Result

p-value: p=≤0.05

Identifies an aggressive incursion of FMDV serotype SAT-2 (topotype VII, lib12 lineage) in Egyptian smallholder water buffaloes in early 2019 that evaded standard trivalent vaccine protection and caused severe viral myocarditis, elevated cardiac biomarkers, and 25.9% adult mortality.

Limitations

Complications may have been exacerbated by confounding factors such as emaciation due to parasitic infections and malnutrition under the smallholder production system
Smallholder farmers often overlook registration of newborn calves, leading to incomplete vaccination coverage and unrecorded susceptibility
DNA sequencing and phylogenetic analysis were performed on only 5 representative isolates out of the 54 RT-PCR-positive samples
Post-mortem and histopathological cardiac examinations were limited to 7 newly deceased buffaloes
Potential confounding by parasitic infections, emaciation, and malnutrition in livestock raised under the smallholder production system
Unregistered newborn calves in smallholder farms may have missed annual FMD vaccination programs
Sequencing was restricted to 5 representative samples and cardiac histopathology to 7 deceased animals

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Implication

May indicate SAT-2 vaccine escape in buffaloes; leaves open prospective cardiac biomarker studies in FMD outbreaks.

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.

Discussion

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Cite This Study

Damaty et al. (2021) conducted a cross-sectional in Acute foot and mouth disease (FMD) in domestic Nile water buffaloes (Bubalus bubalis) (n=54). Foot and mouth disease virus (FMDV) serotype SAT-2 (topotype VII, lib12 lineage) infection vs. Standard reference ranges and previously isolated/vaccine FMDV strains was evaluated on FMDV serotype SAT-2 positivity by RT-PCR and adult buffalo mortality due to heart failure/myocarditis (p=≤0.05). FMDV serotype SAT-2 (topotype VII, lib12 lineage) was detected in 100% (54/54) of sampled water buffaloes, causing 25.9% (14/54) adult mortality with elevated cTnI and myocarditis.

synapsesocial.com/papers/6a92b86f1bc865c2674a1387 https://doi.org/10.3390/ani11061697

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

Figures

Key Points

Study Design

Structured PICO

Main Result

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

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

Figures

Key Points

Study Design

Structured PICO

Main Result

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

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