THE MOLECULAR-GENETICS OF FELINE CORONAVIRUSES - COMPARATIVE SEQUENCE-ANALYSIS OF THE ORF7A/7B TRANSCRIPTION UNIT OF DIFFERENT BIOTYPES
THE MOLECULAR-GENETICS OF FELINE CORONAVIRUSES - COMPARATIVE SEQUENCE-ANALYSIS OF THE ORF7A/7B TRANSCRIPTION UNIT OF DIFFERENT BIOTYPES
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DOI：
10.1006/viro.1995.1520
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发表时间：
1995-10-01
期刊：
影响因子：
3.7
通讯作者：
DEGROOT, RJ
中科院分区：
文献类型：
--
作者：
HERREWEGH, AAPM;VENNEMA, H;DEGROOT, RJ
根据致病性，将猫冠状病毒（FCoVs）分为猫肠道冠状病毒（FECVs）和猫感染性腹膜炎病毒（fipv）。在血清学上，已经区分了I型和II型fcov，后者更接近犬冠状病毒（CCV）。为了更深入地了解不同FCoV生物型之间的遗传关系，我们测定了9株菌株ORF7a/7b转录单元的核苷酸序列。观察结果如下：(i)序列完全相同87-100%。在基因组的这一部分，I型和II型fcov彼此之间的关系比与CCV的关系更密切。为了解释I型和II型FCoV刺状基因之间的遗传和抗原差异，我们假设II型FCoV是由I型FCoV和CCV之间的RNA重组事件引起的。（II）无毒的“FECV”菌株UCD和79-1683与毒性的“FIPV”菌株更相似。因此，我们的发现支持了FECV和FIPV不是不同的物种，而只是毒力变异的观点。（iii）与FECV 79-1683相比，FECV UCD含有一个完整的ORF7b，这表明ORF7b缺失并不是FECV的普遍特征。（iv） ORF7b缺失很容易在体外发生，与毒力丧失相关。通过逆转录-聚合酶链反应分析，我们发现在自然发生的fcov中ORF7b是维持的。因此，ORF7b似乎在自然感染中提供了明显的选择优势。(C) 1995学术出版社，Inc。
Feline coronaviruses (FCoVs) have been subdivided into feline enteric coronaviruses (FECVs) and feline infectious peritonitis viruses (FIPVs) on the basis of pathogenic properties. Serologically, a distinction has been made between type I and II FCoVs, the latter of which more closely resemble canine coronavirus (CCV). To gain more insight into the genetic relationships between different FCoV biotypes, we determined the nucleotide sequences of the ORF7a/7b transcription unit of nine strains. The following observations were made: (i) The sequences are 87-100% identical. In this part of the genome, type I and II FCoVs are more closely related to each other than to CCV. To explain the genetic and antigenic differences between the spike genes of type I and II FCoVs, we postulate that type II FCoVs have arisen by an RNA recombination event between a type I FCoV and CCV, (ii) The avirulent ''FECV'' strains UCD and 79-1683 are more similar to virulent ''FIPV'' strains than to each other. Our findings thus support the notion that FECV and FIPV are not different species but merely virulence variants. (iii) In contrast to FECV 79-1683, FECV UCD contains an intact ORF7b, indicating that ORF7b deletions are not a universal distinguishing property of FECVs. (iv) ORF7b deletions readily occur in vitro, correlating with loss of virulence. By reverse transcription- polymerase chain reaction analysis, we show that in naturally occurring FCoVs ORF7b is maintained. Thus, ORF7b seems to provide a distinct selective advantage during natural infection. (C) 1995 Academic Press, Inc.