This study was aimed at investigating the infection status of orf virus(ORFV)and the genetic evolution characteristics of epidemic ORFV isolates from Anhui province.A total of 303 clinical samples collected from major meat sheep breeding cities in An-hui during 2021-2023 were subjected to ORFV detection with fluorescence quantitative PCR(qPCR).The full-length B2L and F1L genes of ORFV in the positive samples were amplified through conventional PCR and sequenced.Genetic evolution analysis of the B2L and F1L genes was conducted after sequencing.The qPCR results indicated a total ORFV positivity rate in the clinical samples of 48.8%(148/303).Multiple sequence comparisons indicated that the B2L genes of 56 sample isolates shared 96.7%-100.0%DNA and 97.4%-100.0%amino acid sequence identity.Moreover,the F2L genes of 56 sample isolates shared 95.1%-100.0%DNA and 95.0%-100.0%amino acid sequence identity.The genetic evolution tree constructed with the B2L gene DNA sequences indicated sample iso-lates and 21 reference strains located in subgroup 1,and 26 sheep-derived sample isolates and 17 reference strains located in sub-group 2.Among them,the goat-derived sample isolate FY-TYA was located in the same sub-branch as the human-derived reference strain Gansu,whereas the goat-derived sample isolate FY-XQC was located in the same sub-branch as the reference strains China Vaccine and OV-HLJ-04.The genetic evolution tree constructed with the F1L gene DNA sequences showed,the goat sample isolates FY-XQA and FY-XQC were located in the same sub-branch as the sheep-derived reference strain Xinjiang.ORFV infection was rela-tively widespread in the major meat sheep breeding areas of Anhui province,and the DNA and amino acid sequences of the B2L and F1L genes of current circulating ORFV isolates showed different degrees of genetic variation,among which F1L gene had a high de-gree of variation.Furthermore,some goat-derived sample isolates were closely related to human,vaccine,and sheep-derived refer-ence strains.These results may serve as a reference for the prevention and control of ORFV infection in Anhui province.

This study was aimed at investigating the infection status of orf virus(ORFV)and the genetic evolution characteristics of epidemic ORFV isolates from Anhui province.A total of 303 clinical samples collected from major meat sheep breeding cities in An-hui during 2021-2023 were subjected to ORFV detection with fluorescence quantitative PCR(qPCR).The full-length B2L and F1L genes of ORFV in the positive samples were amplified through conventional PCR and sequenced.Genetic evolution analysis of the B2L and F1L genes was conducted after sequencing.The qPCR results indicated a total ORFV positivity rate in the clinical samples of 48.8%(148/303).Multiple sequence comparisons indicated that the B2L genes of 56 sample isolates shared 96.7%-100.0%DNA and 97.4%-100.0%amino acid sequence identity.Moreover,the F2L genes of 56 sample isolates shared 95.1%-100.0%DNA and 95.0%-100.0%amino acid sequence identity.The genetic evolution tree constructed with the B2L gene DNA sequences indicated sample iso-lates and 21 reference strains located in subgroup 1,and 26 sheep-derived sample isolates and 17 reference strains located in sub-group 2.Among them,the goat-derived sample isolate FY-TYA was located in the same sub-branch as the human-derived reference strain Gansu,whereas the goat-derived sample isolate FY-XQC was located in the same sub-branch as the reference strains China Vaccine and OV-HLJ-04.The genetic evolution tree constructed with the F1L gene DNA sequences showed,the goat sample isolates FY-XQA and FY-XQC were located in the same sub-branch as the sheep-derived reference strain Xinjiang.ORFV infection was rela-tively widespread in the major meat sheep breeding areas of Anhui province,and the DNA and amino acid sequences of the B2L and F1L genes of current circulating ORFV isolates showed different degrees of genetic variation,among which F1L gene had a high de-gree of variation.Furthermore,some goat-derived sample isolates were closely related to human,vaccine,and sheep-derived refer-ence strains.These results may serve as a reference for the prevention and control of ORFV infection in Anhui province.