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Abstract
This study was performed to study the prevalence of FMD virus in four geographical areas of Egypt suffered from fatal and dangerous FMD outbreaks that differ from current FMD outbreaks with high morbidities and mortalities in livestock. Ismailia, Gharbia, Dakahlia and Kafr El_Sheikh provinces were selected to predict FMDV serotypes. A total of 54 animals (31 cattle and 23 buffaloes) were examined, out of them 35 clinically infected and 19 apparently healthy animals. from each animal, OP fluids, sterile vesicular fluids, saliva and tongue epithelium were collected for FMDV isolation and identification.
The collected samples were routinely prepared and inoculated intraperitonealy in unweaned suckling mice as well as primary bovine kidney cell culture and/or BHK21 cell line. Mice died in the first 24 hours post inoculation considered non specific death. Mice showed twisting and paralysis of hind limbs are sacrified and brain collected as a source of FMD viral antigen. Inoculated tissue cultures are examined three times daily for the appearance of specific FMDV cytopathic effect. After 4 days post inoculation, the culture are frozen and thawed three times and used as a source of FMD viral antigen.
FMDV suspected isolates either collected from tissue culture or mice brain were examined and typed for the presence of FMD viral antigen with ELISA and complement fixation tests. A total of 48 FMDV strains were detected with a total percentage of 88.88%. 35 FMD strains out of 48 are serotyped as O strain with a percentage of 72.90% while 13 FMD strains are serotyped as A strain with a percentage of 27.10% from the total number of FMDV isolates.
FMDV was isolated from cattle and buffaloes in Ismailia, Gharbia, Dakahilia and Kafr El_Sheikh provinces with a total percentage of 82.35%, 86.67%, 100% and 87.50% respectively. The isolation rate of FMDV from cattle in the four province are 52.94%, 40%, 50% and 62.50% respectively, mean while in buffaloes are 29.41%, 46.67%, 50% and 25% respectively.
Carrier state of FMDV in apparently healthy cattle and buffaloes were varied according to the province, in Ismailia, the samples showed high prevalence with a percentage of 63.63% in cattle and 9.09% in buffaloes, in Gharbia, cattle (33.,33%) and buffaloes (33.33%), in Dakahlia, cattle (66.67%) and buffaloes (33.33%) and in Kafr El_Sheikh, cattle (100%). FMDV are not isolated from apparently healthy buffaloes in Kafr El_Sheikh Province.
The isolation rate of FMD virus from clinically infected cattle and buffaloes is higher than apparently healthy cattle and buffaloes. In Ismailia, the samples collected from cattle showed isolation rate of 33.33% and in buffaloes 66.67%, in Gharbia cattle 41.67% and buffaloes 50%, in Dakahlia cattle 45.45% and buffaloes 54.54% and in Kafr El_Sheikh cattle 50% and buffaloes 33.33%.
Serotyping of FMD virus isolated from cattle and buffaloes in Ismailia, Gharbia, Dakahilia and Kafr El_Sheikh provinces using ELISA and CFT showed that, serotype O was most prevalent type in cattle and buffaloes in the four provinces with a percentage of 41.17%, 86.67%, 57.14% and 87.50% respectively while serotype A was isolated only from cattle and buffaloes in Ismailia and Dakahlia provinces with a percentage of 41.17% and 42.86%. This is no FMDV serotype A were isolated from cattle and buffaloes examined in Gharbia and Kafr El_Sheikh provinces.
RT-PCR is used to confirm the isolated FMDV serotype O genetically and compare the isolated O strains with the locally used O vaccinal strains in Egypt. A total of 30 FMDV strains serotype O and the vaccinal O strains were tested using specific FMDV primers. The results showed that, RT-PCR test is more sensitive, specific, reliable and effective safe cost in detection of FMDV serotype O genome, since one strain of FMDV undetected by ELISA test and two strains undetected by CFT are clearly detected by RT-PCR. Vaccinal O strains examined by RT-PCR showed positive bands at 402 bp, the same bands of isolated FMD virus serotype O isolated from clinically infected and apparently healthy animals indicating that vaccinal O strains are genetically and antigenically related to the 30 FMDV isolates serotype O examined and implication of reactivated vaccinal O strains in FMDV outbreaks circulate in the four areas of Egypt.