中国首例兔出血症病毒2型(RHDV2/b/GI.2)的鉴定及病理学观察

First Detection of a Type 2 Rabbit Hemorrhagic Disease Virus(RHDV2/b/GI.2)in China and Its Pathological Observation

本试验旨在鉴定四川金堂某兔场疑似兔出血症病毒2型(RHDV2)感染疫情的病原,并分析病兔的病理组织学变化。利用血凝试验和RT-PCR检测病死兔内脏组织中的病原,取病变组织制作病理切片,观察分析各组织的病理组织学变化,同时应用病兔肝脏悬液感染幼兔,分析该毒株的致病力。血凝试验结果显示,所采集病死兔肝脏样品能凝集人“O”型血红细胞;RT-PCR扩增及测序结果显示,多对引物均能从样品中扩增出RHDV2特异性条带;病理组织学观察结果显示,病兔多脏器严重出血、肿胀,淋巴细胞和中性粒细胞大量浸润,气管黏膜、肝脏、肺脏出血尤为严重;动物试验结果显示,该毒株毒力较强,含毒肝脏悬液能在24 h内迅速致死幼兔。本研究经临床诊断、核酸检测及测序证实了此次疫情确由RHDV2感染引起,动物试验和病理组织学观察表明该毒株毒力较强,可引发脏器严重出血,造成病兔急性死亡,RHDV2的出现提示病毒的跨境传播情况不容乐观,应引起更大的重视。

The purpose of this study was to identify the suspected etiology of Rabbit hemorrhagic virus type 2(RHDV2)infection in a rabbit farm in Jintang,Sichuan province,and to analyze the pathological histological changes of the infected rabbits.Hemagglutination test(HA)and RT-PCR were used to detect and identify the pathogens of the rabbit,and then pathological sections were taken from the diseased tissue to observe and analyze the histopathological changes of each tissue.At the same time,liver suspension was used to infect young rabbits,and the virulence of this strain was analyzed.The results of HA showed that liver samples collected from diseased and dead rabbits could agglutinate human“O”red blood cells.RT-PCR and sequencing results showed that RHDV2 specific bands were amplified from the samples with multiple pairs of primers.The histopathology microscopic examination revealed that the rabbit displayed systemic hemorrhagic and internal swelling with infiltration of large lymphocytes and neutrophils,and the hemorrhagic in liver,lung,and tracheal mucosa were the most serious.The animal test results showed that this strain was highly virulent,and the liver suspension containing RHDV2 was lethal to young rabbits and caused death in 24 h.In this study,clinical diagnosis,nucleic acid testing and sequencing confirmed that the outbreak was caused by RHDV2 infection.Animal tests and histopathological observation showed that this strain was virulent,which could cause serious bleeding organs,resulting in acute death of the sick rabbit.The emergence of RHDV2 indicated that the cross-border spread of virus was not optimistic,and it should be seriously monitored.