College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China.
Guangdong Provincial Key Laboratory of Prevention and Control for Severe Clinical Animal Diseases, Guangzhou 510642, China.
Int J Mol Sci. 2022 Jun 7;23(12):6382. doi: 10.3390/ijms23126382.
Canine circovirus (CanineCV) is an emerging virus in canines. Since the first strain of CanineCV was reported in 2012, CanineCV infection has shown a trend toward becoming a global epidemic. CanineCV infection often occurs with coinfection with other pathogens that may aggravate the symptoms of disease in affected dogs. Currently, CanineCV has not been successfully isolated by laboratories, resulting in a lack of clarity regarding its physicochemical properties, replication process, and pathogenic characteristics. To address this knowledge gap, the following results were obtained in this study. First, a CanineCV strain was rescued in F81 cells using infectious clone plasmids. Second, the Rep protein produced by the viral packaging rescue process was found to be associated with cytopathic effects. Additionally, the Rep protein and CanineCV inhibited the activation of the type I interferon (IFN-I) promoter, blocking subsequent expression of interferon-stimulated genes (ISGs). Furthermore, Rep was found to broadly inhibit host protein expression. We speculate that in CanineCV and canine parvovirus type 2 (CPV-2) coinfection cases, CanineCV promotes CPV-2 replication by inducing immunosuppression, which may increase the severity of clinical symptoms.
犬圆环病毒（CanineCV）是犬类中的一种新兴病毒。自 2012 年首次报告犬圆环病毒以来，该病毒的感染呈全球流行趋势。犬圆环病毒感染常与其他病原体的合并感染有关，这可能会加重受感染犬的疾病症状。目前，实验室尚未成功分离出犬圆环病毒，因此其理化性质、复制过程和致病特征尚不清楚。为了填补这一知识空白，本研究取得了以下结果。首先，使用感染性克隆质粒在 F81 细胞中拯救了一株犬圆环病毒。其次，发现病毒包装拯救过程中产生的 Rep 蛋白与致细胞病变效应有关。此外，Rep 蛋白和犬圆环病毒抑制了 I 型干扰素（IFN-I）启动子的激活，阻断了干扰素刺激基因（ISGs）的后续表达。此外，还发现 Rep 广泛抑制宿主蛋白的表达。我们推测，在犬圆环病毒和犬细小病毒 2 型（CPV-2）混合感染的情况下，犬圆环病毒通过诱导免疫抑制促进 CPV-2 的复制，这可能会增加临床症状的严重程度。
