对虾白斑综合征病毒新株型WSSV-CN-Pc的毒力研究

对虾白斑综合征病毒(white spot syndrome virus,WSSV)是一种能够感染虾类并且造成其大面积死亡的环状双链DNA病毒。WSSV有多种分离株,其毒力有所差异。从克氏原螯虾(Procambarus clarkii)中分离得到1株WSSV新分离株WSSV-CN-Pc,其毒力尚不清楚。本研究采用肌肉注射和经口注射的方法,以WSSVTW型作为阳性对照,分别对克氏原螯虾(P.clarkii)和罗氏沼虾(Macrobrachium rosenbergii)进行活体实验。实验结果显示:肌肉注射WSSV-CN-Pc和WSSV-TW的克氏原螯虾均在第6天出现100%的死亡;罗氏沼虾在肌肉注射WSSV-TW后未出现死亡,但在注射WSSV-CN-Pc后的第9天死亡率达100%。经口注射WSSV-CN-Pc和WSSV-TW的克氏原螯虾均在第16天出现100%的死亡;罗氏沼虾经口注射WSSV-CN-Pc后的第19天死亡率为100%,但注射WSSV-TW的实验组并未出现死亡。结果表明,对于克氏原螯虾,WSSV-CN-Pc具有和WSSV-TW相似的毒力,而对罗氏沼虾存在明显的毒力差异。提示克氏原螯虾是WSSV传播途径中的重要因素。

Virulence of White Spot Syndrome Virus New Strain WSSV-CN-Pc of Prawn

WSSV (white spot syndrome virus) of prawn is a kind of circle shaped double stranded DNA virus that could infect shrimps and results in mortality. WSSV has multiple isolate strains, and their virulence is different to some extent. WSSV-CN-Pc is a new strain that was isolated from crayfish (Procambarus clarkii) with unclear virulence. To understand its virulence, crayfish (P. clarkii) and shrimp (Macrobrachium rosenbergii) were respectively injected in vivo with WSSV-CN-Pc and with WSSV-TW as positive control via intramuscular injection and oral injection. The results showed that WSSV-CN-Pc and WSSV-TW resulted 100% mortality in crayfish (P. clarkia) at 6d upon the intramuscular injection; but no mortality in M. rosenbergii, however, it reached 100% mortality at 9 d. The mortality of P. clarkia reached to 100% at 16 d after oral injected with the WSSV-CN-Pc and WSSV-TW; as for M. rosenbergii, it reached to 100% mortality at 19d after oral injected with WSSV-CN-Pc, but no mortality was observed in WSSV-TW injection experiment group. These results indicated that WSSV-CN-Pc and WSSV-TW had similar virulence upon infection of P. clarkia, but had significant difference against M. rosenbergii. It implied that natural P. clarkia may be an important spreading channel of WSSV transmission.