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INTRODUCTION: Three strains of the FMD virus (A, O, and SAT 2) were recognised as causes of the FMD circulating in Egypt. The aims of this study were to trace the FMDV isolates from outbreaks in Egypt to understand their epidemiology and evolution and to understand the situation of the vaccine strains compared with the circulating serotypes. MATERIAL AND METHODS: A meta-analysis was carried out by using the data available for FMD outbreaks in Egypt from GenBank and the World Reference Laboratory for Foot-and-Mouth Disease (WRLFMD); a comparison was done with both data sets for the three serotypes. MEGA-X was used for the evolution analysis, through constructions of phylogenetic trees for all sequences recorded in GenBank for each serotype in different Egyptian outbreaks in different years and also within the same year. Additionally, nucleotide substitution rate, molecular clock, and mean evolutionary rates were estimated for the three serotypes to understand and compare their evolution. RESULTS: Absence of some records of certain serotype outbreaks from the WRLFMD database was noted as were subsequent missing appropriate vaccine programmes. Genetic variation was recorded among the virus isolates within the same years and also the vaccine strain was associated with up to 26 amino acid substitutions. The evolution rate of the SAT2 strain was the highest of the circulating strains. SAT2 had high amino acid substitution per year at an important immunogenic site (130-170), serotype A had less, and serotype O the least. CONCLUSION: The need for different strategies for vaccine serotype selection is indicated.
RESUMEN
AIM: The present study was aimed to investigate the epidemic situation of foot-and-mouth disease (FMD) in Egypt from 2016 to 2018 based on the detection of FMD virus (FMDV) in carrier or previously infected animals, by determination of antibodies against non-structural protein (NSP), implementation a pilot study on circulating FMDV serotypes and assure the efficacy of locally produced inactivated trivalent vaccine. MATERIALS AND METHODS: A total of 1500 sera were collected from apparent healthy vaccinated cattle and buffaloes from three Egyptian geographical sectors, representing ten governorates. Determination of FMD antibodies against NSP was carried out using 3ABC enzyme-linked immunosorbent assay (ELISA) test. Serotyping of the circulating FMDV and assure the vaccine efficacy was performed using solid-phase competitive ELISA. RESULTS: The 3ABC ELISA test revealed 26.4% and 23.7% positive for FMDV-NSP antibodies in cattle and buffalo sera, respectively. The highest positivity was in Delta Sector among both cattle 42.3% and buffaloes 28.8%. Serotyping of FMDV-positive NSP sera in El-Qalyubia Governorate for the circulating FMDV serotypes O, A, and Southern African Territories (SAT) 2 was 52.2%, 17.4%, and 30.4% in cattle and 31.8%, 27.3%, and 40.9% in buffaloes, respectively. The overall protection level due to the vaccination program was 62.1 and 60.9% in cattle and buffaloes, respectively, while the protective level of the FMDV serotypes O, A, and SAT2 included in the inactivated trivalent vaccine was 73.9, 84.6, and 63.8% in cattle and 72.3, 82.3, and 63.5% in buffaloes, respectively. CONCLUSION: The present study recommended full determination for the immunogenic relationship between the vaccine strains and the field strains to attain maximum protection against the circulating viruses.
