Investigation on the Contamination with CSFV,PRV and PRRSV in Bio-safety Disposal Plants in Hunan Province from 2021 to 2023
In order to investigate the contamination with classical swine fever virus(CSFV),pseudorabies virus(PRV)and porcine reproductive and respiratory syndrome virus(PRRSV)in bio-safety disposal plants in Hunan Province from 2021 to 2023,1 825 tissue samples including lymph nodes,spleens and ear tips were detected for nucleic acids of the three viruses by RT-qPCR,and positive samples of PRRSV from Hengnan County in 2022 were typed and sequenced for Nsp2 gene.The results showed that the positive detection rates of CSFV,PRV and PRRSV were 3.01％,1.81％and 30.14％,respectively;the double infection rate was 2.52％,which was mainly contributed by PRRSV and other two pathogens,but the triple infection rate was lower,only 0.05％.The positive detection rate of PRRSV was 24.12％in bio-safety disposal plants in Hengnan County in 2022,especially in spring and winter;that of North American type(NA-PRRSV),highly pathogenic type(HP-PRRSV)and NADC30 like strain(NADC30like)were 98.39％,20.97％and 43.55％,respectively;based on Nsp2 gene sequencing,"1+29"discontinuous amino acids were deleted in one sequence determined as HP-PRRSV strain,and"111+1+19"discontinuous amino acids were deleted in 17 sequences determined as NADC30-like strains.In conclusion,CSFV and PRV were available in bio-safety disposal plants in Hunan Province at a low contamination rate from 2021 to 2023,except PRRSV with a high and increasing contamination rate,especially NADC30-like strains that were dominant,with an increasing trend year by year.For safeguarding the safety of pig production,vaccination against classical swine fever and pseudorabies should be continuously implemented with evaluation on the immune effects,genetic variation of PRRSV should be intensively monitored,feeding and biosecurity on farms should be rigorously managed.
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