犬猫冠状病毒研究进展

Research Progress of Canine Coronavirus and Feline Coronavirus

犬冠状病毒(canine coronavirus,CCoV)与猫冠状病毒(feline coronavirus,FCoV)同属于冠状病毒科冠状病毒属α属,与其同属的病毒还有猪传染性胃肠炎病毒(porcine transmissible gastroenteritis virus,TGEV)、猪流行性腹泻病毒(porcine epidemic diarrhea virus,PEDV)等。遗传进化分析表明,该种属不同基因型病毒通过基因重组能产生新型变异毒株,为疾病的诊断与防控造成了很大的阻碍。β属冠状病毒包括牛冠状病毒(bovine coronavirus,BCoV)、犬呼吸道冠状病毒(canine respiratory coronavirus,CRCoV)、严重急性呼吸综合征冠状病毒(severe acute respiratory syndrome coronavirus,SARS-CoV)等,其中CRCoV与BCoV同源性较高,该类病毒与α属冠状病毒在基因组结构、致病机制、感染症状等方面差异较大。CCoV与FCoV在全球范围内广泛传播,具有发病率高、死亡率低的特点。由于RNA病毒本身的特点和环境选择压力的影响,这两种病毒不断变异进化,新的强致病力毒株相继出现。经FCoV基因突变演化而来的猫传染性腹膜炎病毒(feline infectious peritonitis virus,FIPV)毒力大大增强,病毒基因组中某些特异性的点突变使得针对宿主的细胞嗜性发生改变,该病毒的致病机制主要依赖于病毒感染后诱导机体产生的抗体依赖性增强作用(ADE)。针对犬猫冠状病毒的流行病学调查及防控不能仅依赖于疫苗免疫单一因素,还应综合考虑病毒毒力、环境条件、宠物自身免疫抵抗力状态等。针对犬猫冠状病毒的诊断应根据临床症状,结合常规血液学检查、血清生化检查和实验室诊断技术来进行全面的鉴定,防止出现假阳性及假阴性结果。

Canine coronavirus(CCoV)and feline coronavirus(FCoV)belong toα-genus coronavirus of coronavirus family,porcine transmissible gastroenteritis virus(TGEV),porcine epidemic diarrhea virus(PEDV)also belong to the same genus.Genetic evolution analysis showed that different genotype of the virus could produce new variant strains through gene recombination,which caused great obstacles to the diagnosis and control of the disease.β-genus coronaviruses include bovine coronavirus(BCoV),canine respiratory coronavirus(CRCoV)and severe acute respiratory syndrome coronavirus(SARS-CoV).Among them,CRCoV has the highest homology with BCoV,but there are great differences in genomic structure,pathogenic mechanism and infection symptoms between this kind of coronavirus andα-coronavirus.CCoV and FCoV are widely spreading around the world,characterized by high morbidity and low mortality.Due to the characteristics of RNA virus and the influence of environmental selection pressure,the viruses continue to mutate and evolve,and new virulent strains appear one after another.The virulence of feline infectious peritonitis virus(FIPV)is greatly enhanced,some specific point mutations in the virus genome change the cellular tropism against the host.The pathogenesis of the virus mainly depends on the antibody-dependent enhancement(ADE)induced by virus infection.The epidemiological investigation and prevention and control of CCoV and FCoV should not only rely on the single factor of vaccine immunity,but also comprehensively consider the virulence of the virus,environmental conditions,pet self-immune resistance,and so on.The identification of CCoV and FCoV should be based on clinical symptoms,combined with routine hematological examination,serum biochemical examination and laboratory diagnosis techniques to prevent false positive and false negative results.