Sun Fanyuan, Guo Xinyi, Guo Jinfan, Zhu Min, Zhou Huabo, Chen Jiancai, Huang Xin, Chen Hewei, Xu Yi, Zhu Yaohui, Wang Pingping, Huang Chongqiang, Long Jianming, Ouyang Kang, Wei Zuzhang, Huang Weijian, Chen Ying
Laboratory of Animal Infectious Diseases and Molecular Immunology, College of Animal Science and Technology, Guangxi University, Nanning 530004, China.
Huabo Pet Hospital, Nanning 530004, China.
Transbound Emerg Dis. 2023 Feb 27;2023:1145176. doi: 10.1155/2023/1145176. eCollection 2023.
Feline calicivirus (FCV) is a highly contagious pathogen associated with oral and upper respiratory tract diseases (URTD), and it is also possibly considered as an enteric pathogen. Some studies found FCV-like viruses in the enteric tract of dogs, but there was a lack of understanding regarding the epidemiology and biological properties of FCVs in dogs. In this study, 252 fecal/feces samples were collected from dogs, with or without diarrhea, from 2020 to 2021. There were 6 FCV-positive samples (2.41%, 6/252), from which only two FCVs were successfully isolated and the complete genome sequences obtained. Phylogenetic analysis showed that the two canine-origin FCV isolates belonged to genogroup I and formed a monophyletic cluster with previous FCV strains, sharing a common ancestor. However, there was genetic diversity when the nt identity of the VP1 proteins between the two canine-origin FCV isolates (77.4% nt identity) was compared. In particular, the genomic sequence of the canine/GXHC01-21 isolate showed evidence of recombination at the 3' end of the ORF1 gene with sequence identity very similar to the FCV strain, GX2019, previously isolated from cats in Guangxi in 2019. A comparison of their replication properties indicated that the two isolates could not replicate efficiently in MDCK cells. This was also seen in the enteric FCV isolate, GXNN04-20. However, both displayed similar plaque phenotypes to the respiratory FCV isolate, GX01-13. In addition, it was found that sera from vaccinated cats had low cross-reactivity in a neutralizing antibody test against the two canine-origin FCV isolates. Moreover, high neutralizing antibody titers (≥1 : 128) against canine-origin FCV viruses were observed in the two canine serum samples. This confirmed that interspecies transmission had occurred between cats and dogs. Our results provided an in-depth understanding of the genetic evolution and characteristics of FCVs circulating in dogs.
猫杯状病毒（FCV）是一种与口腔和上呼吸道疾病（URTD）相关的高度传染性病原体，也可能被视为一种肠道病原体。一些研究在犬的肠道中发现了类似FCV的病毒，但对犬源FCV的流行病学和生物学特性缺乏了解。在本研究中，于2020年至2021年从有或无腹泻的犬只中收集了252份粪便样本。有6份FCV阳性样本（2.41%，6/252），其中仅成功分离出两株FCV并获得了完整的基因组序列。系统发育分析表明，这两株犬源FCV分离株属于基因群I，与先前的FCV毒株形成一个单系簇，有一个共同的祖先。然而，比较两株犬源FCV分离株之间VP1蛋白的核苷酸同一性时存在遗传多样性（核苷酸同一性为77.4%）。特别是，犬/GXHC01 - 21分离株的基因组序列显示在ORF1基因的3'端有重组迹象，其序列同一性与2019年从广西猫中分离的FCV毒株GX2019非常相似。对它们复制特性的比较表明，这两株分离株在MDCK细胞中不能高效复制。在肠道FCV分离株GXNN04 - 20中也观察到了这一点。然而，两者与呼吸道FCV分离株GX01 - 13表现出相似的蚀斑表型。此外，发现在针对两株犬源FCV分离株的中和抗体试验中，接种疫苗的猫血清交叉反应性较低。而且，在两份犬血清样本中观察到针对犬源FCV病毒的高中和抗体滴度（≥1∶128）。这证实了猫和犬之间发生了种间传播。我们的结果提供了对犬中循环的FCV的遗传进化和特征的深入理解。
