Complete genome sequence analysis of Reticuloendotheliosis virus integrated in nonhomologous Avipoxvirus.

Integration of nucleic acid sequences of Reticuloendotheliosis virus (REV) in Avipoxvirus（APV） has become commonplace. In this study, 4 strains of suspected Fowlpox virus (FPV) and 1 strain of suspected Pigeonpox virus (PPV) collected in Taiyuan, Shanxi Province were cultured in chicken embryos, and the 4b core protein gene was amplified by PCR, and the identity and genome similarity were determined by sequence analysis. The sequences between the end of ORF201 and the beginning of ORF203 of FPV and PPV were then amplified, sequenced, and subjected to sequence comparison to determine genome similarity. The results showed that the isolates were 4 strains of FPV and 1 strain of PPV. The 4 isolated strains of FPV belong to type A1 virus, with 100 % identity to each other and to the FWPV-09-Jilin strain isolated in Jilin, China, and the lowest identity to the type B2 virus TNPV5/NZL/2009, which is only 74 %. PPV belongs to type A2 virus, and its identity with local strain of fowlpox virus was 90.1 %, with the highest identity of 100 % with PPLH and ROPI/W370/ON/2012 and ow_2017_3 strains, which also belong to type A2 pigeonpox virus, and the lowest identity of 73.7 % with TNPV5/NZL/2009, a type B2 virus. The complete genome of REV sequences integrated into FPV and PPV were amplified, and 5 REV nucleic acid sequences were obtained after sequencing and concatenation, with lengths ranging from 7942 to 8005 bp. The identity analysis results indicate that it has high identity with isolates from Northeast China, Guangdong, and Guangxi regions in China. Based on its gp90 protein gene, the REV integrated into the poxvirus belong to type III, with the highest identity of 99.9% with strains such as APC-566 and CY1111, and the lowest identity with REV-Anhui1, at 95.4 %. The length of the pol gene varies among different strains of REV, and its encoded amino acid changes significantly after position 675, with deletions and alterations. This study indicates that all fowlpox viruses isolated in Taiyuan, Shanxi Province have integrated the entire REV gene sequence, with high identity between them. At the same time, it indicates that the pigeonpox virus isolate has also integrated the entire REV gene sequence, and has the highest identity with the integrated REV gene sequence in fowlpox virus.

Isolation and identification of a pigeonpox virus strain and study on the integration of reticuloendotheliosis virus sequence.

In order to study the integration of reticuloendotheliosis virus (REV) in pigeonpox virus (PPV), we collected suspected pigeonpox disease material, amplified the 4b core protein gene of PPV, the gp90 gene of REV, and the integrated sequence fragments from the end of the ORF201 segment of PPV to the beginning of the LTR of REV, and sequenced these genes. The results showed that a 4b core protein fragment of 332 bp was amplified and identified as pigeonpox virus, which was named SX/TY/LTR 01/2023. Sequence analysis showed that the pigeonpox virus isolate belonged to genotype A2, which was the closest to the domestic CVL strain, with a identity of 99.4%. A band of 1191 bp was amplified from the gp90 gene of REV, named SX/TY/PPV-REV01/2023, and sequence analysis indicated that REV belonged to genotype III. The sequence analysis showed that REV belonged to genotype III, and belonged to the same large branch as the domestic isolates JSRD0701 and LNR0801, with 99.3% identity. The integrated sequence fragment was amplified to a band of 637 bp, which determined that the REV sequence was integrated in the PPV rather than a mixed infection of the two viruses. This indicates that REV was integrated in this isolation of PPV, suggesting that pigeon farms need to prevent reticuloendotheliosis at the same time when preventing pigeonpox.

Complete genome sequence analysis and biological characteristics of Newcastle disease viruses from different hosts in China.

Newcastle disease (ND) is one of the most serious diseases affecting poultry worldwide. In 2022, we studied two strains of Newcastle disease virus (NDV) from pigeons and magpies identified by PCR and propagated in SPF chicken embryos. The whole genome of the virus was then expanded and its biological characteristics were studied. The results showed that NDV was isolated from pigeons and magpies. Virus present in the allantoic fluid could agglutinate red blood cells and could not be neutralized by serum positive for avian influenza. Sequencing showed that the gene length of the two isolates was 15,191 bp, had high homology and was located in the same branch of the phylogenetic tree, both belonging to genotype VI.1.1. The sequence of 112-117 amino acids in the F gene sequence was 112R-R-Q-K-R-F117, which constituted virulent strain characteristics. The HN gene contained 577 amino acids, which is also consistent with the characteristics of a virulent strain. The results from the study of biological characteristics revealed that the virulence of SX/TY/Pi01/22 was slightly stronger. There were only four different bases in the complete sequence of the two strains. Comprehensive analysis revealed that the G at 11,847 site of the SX/TY/Ma01/22 strain may change to T, leading to translation of amino acids from R to S, thereby weakening viral virulence. Therefore, NDV was transmitted from pigeons to magpies, indicating that the pathogen could be transmitted between poultry and wild birds.