Genetic drift and genetic shift during feline coronavirus evolution
Genetic drift and genetic shift during feline coronavirus evolution
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DOI：
10.1016/s0378-1135(99)00102-9
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发表时间：
1999-09-01
影响因子：
3.3
通讯作者：
Vennema, H
中科院分区：
文献类型：
--
作者：
Vennema, H
猫冠状病毒(FCoV)可分为引起猫传染性腹膜炎(FIP)的毒株和引起亚临床到轻度肠道感染的猫科肠道冠状病毒(FECV)。此外，组织培养适应FIPV毒株的存在，已经失去了致病能力。这种现象伴随着7b基因的缺失(但不一定是由其引起的)(Herrewegh等人，1995)。目前可用的疫苗病毒就是减毒株的一个例子。FIPV和FECV在血清学或形态上无法区分，因此被称为猫冠状病毒的生物型；这两种病毒仅在生物学上不同。这项研究的目的是证明生物型是不同的，并找出(重要的)差异所在。对一次疫区暴发的FECV毒株和FIPV毒株进行了基因比较。这些菌株的生物型是通过实验感染建立的(Hickman等人，1995年)。遗传比较表明，不同表型的菌株在遗传上的亲缘关系可能比来自其他地理背景的相同表型的菌株更密切(Vennema等人，1995,1998)。这一观察结果以及FIP病例是在广泛感染FECV之后出现的事实表明，FIPV是FECV的变种(Hickman等人，1995年)。为了找到这一假说的证据，我们用相同的FECV毒株感染了19只猫，并寻找FIP的临床迹象，这将表明突变的出现(波兰等人，1996年)。这些动物通过感染猫免疫缺陷病毒(FIV)而受到免疫抑制，以增加在相对较少数量的猫中发现突变的机会。现已证实，FIV阳性猫的粪便中FCoV病毒滴度是对照组的10到100倍，排出病毒的时间更长，延迟时间更长，产生的抗体水平也更低。8周和10周后，其中两只猫下来了
Feline coronaviruses (FCoVs) can be divided in strains that cause feline infectious peritonitis (FIP) and strains that cause a subclinical to mild enteric infection, feline enteric coronavirus (FECV). Furthermore, tissue culture adapted FIPV strains exist, that have lost the ability to cause disease. This phenomenon is accompanied by (but not necessarily caused by) deletions in the 7b gene (Herrewegh et al., 1995). The currently available vaccine virus is an example of the attenuated strains. FIPV and FECV cannot be distinguished serologically or morphologically and were therefore called biotypes of the feline coronaviruses; the two viruses differ only biologically. The object of the research was to demonstrate that the biotypes are genetically different and to find out where the (important) differences are located.A genetic comparison was made of an FECV strain and an FIPV strain from one focal outbreak. The biotypes of these strains were established by experimental infection (Hickman et al., 1995). The genetic comparison revealed that strains of different phenotypes can be genetically more closely related than strains with the same phenotype from other geographic backgrounds (Vennema et al., 1995, 1998). This observation and the fact that the FIP cases followed a widespread infection with FECV, suggested that the FIPV emerged as a variant of FECV (Hickman et al., 1995). To find evidence for this hypothesis we infected 19 cats with the same strain of FECV and looked for clinical signs of FIP which would be indicative of the appearance of a mutant (Poland et al., 1996). The animals were immunosuppressed through feline immunodeficiency virus (FIV) infection to increase the chances of finding a mutant in a relatively small number of cats. It was established that FIV positive cats had 10 to 100-fold higher FCoV viral titers in their faeces, shed virus for a longer period of time and produced lower levels of antibodies after a longer delay than the control cats. After 8 and 10 weeks two of the cats came down