Genetic Variation Analysis of ORF5 Genes of Porcine Reproductive and Respiratory Syndrome Virus in Guangdong Province

Abstract

【Objective】The molecular epidemiological dynamics of porcine reproductive and respiratory syndrome virus (PRRSV) in Guangdong Province in 2021 were monitored in order to provide references for the formulation of comprehensive prevention and control measures for PRRSV.【Method】521 tissue samples of diseased pigs were selected from 37 large-scale farms that were tested positive as PRRSV in different regions of Guangdong Province for ORF5 gene sequencing, then DNAStar was used to analyze the nucleotide homology and deduced amino acid homology of the ORF5 gene, and Mega 7.0 was used to construct ORF5-based phylogenetic tree.【Result】Positive rate of PRRSV was 24.4% in the collected samples, and the positive rate of pig farms was 45.9%. The ORF5 gene sequences of 17 strains of PRRSV from different pig farms were obtained by sequencing. Phylogenetic analysis showed that all the isolates belonged to the North America genotype. Among them, 5 strains belonged to the Lineage 8 (JXA1-like and CH-1a-like) subgroup, 9 strains belonged to the Lineage 1 (NADC30-like and NADC34-like) subgroup, 3 strains belonged to the Lineage 3 (QYYZ-like) subgroup, and no strains of the Lineage 5 (VR2332-like) were detected. The nucleotide sequence homology of ORF5 gene of 17 strains was 81.3%-99.3%, and the deduced amino acid sequence homology was 80.0%-98.3%.【Conclusion】The predominate strains of PRRS in Guangdong Province in 2021 belonged to Lineage 1 (NADC30-like and NADC34-like) and Lineage 8 (JXA1-like and CH-1a-like), accounting for 52.94% and 29.41%, respectively. Lineage 3 (QYYZ-like) was reduced to a secondary epidemic strain, accounting for 17.65%.

Keywords

• porcine reproductive and respiratory syndrome virus (prrsv)
• orf5 gene
• nadc30 strain
• nadc34 strain
• genetic variation