Immunological and Molecular Virological Studies on Rotavirus Infection in Animals

轮状病毒（RV）是引起犊牛急性腹泻的病原之一。RV在动物中的传播方式尚不清楚，尽管据报道RV在动物群体中广泛传播。本研究旨在探讨RV感染动物的分子病毒学和免疫学特征。(1)从1986年至1991年，从一个轻型马场的马群中分离出一系列马RV。各年份的代表性RV均显示出相似的基因组RNA和血清型G3，表明特定RV毒株在该鸡场长期存在。然而，在1987年，一个分离株（CH 3）显示出一种独特的病毒RNA电泳型（EPT），与该农场广泛流行的其他病毒不同。CH 3株的VP 7氨基酸序列与G14株FI 23的氨基酸序列同源性较高，VP 4氨基酸序列与H2株的氨基酸序列相似。(2)上述农场爆发了G3 RV马驹腹泻。在1989年，所有的马驹接受牛初乳免疫球蛋白（IG）粉在流行期间，其发病率低于观察到的1987年，当IG粉没有管理的马驹。这表明给予IG粉末可部分预防马驹腹泻。(3)从新生犊牛流行性腹泻粪便中分离到8株RV。病毒RNA分为5个EPT。然而，一些菌株呈现的不是单一的而是混合的双重或三重EPT构象。这些数据表明，不同RV在同一小牛中的混合感染导致了菌株之间的基因组片段的重新连接。(4)在一个封闭的奶牛场，牛RV分离出35（16%）的222粪便标本重复收集59小牛出生在1990年至1993年。3周龄患牛血清伊加、IgG抗体水平显著高于正常牛（P<0.05）。35株菌中绝大多数分离自2 ~ 6岁犊牛

Rotavirus (RV) is one of the causative agents of acute diarrhea in foals and calves. The mode of RV transmission among animals is still unclear, although RV has been reported to be wide-spreading in the animal populations. The present study is concerned with molecular virologic and immunologic features of RV infection in the animals. (1) A series of equine RVs was isolated from diarrheal foals in a light-horse farm from 1986 to 91. All the represented RVs in each year showed similar genomic RNA and serotype G3, suggesting the persistence of a particular RV strain in this farm for long time. In 1987, however, one isolate (CH3) showed a unique electropherotype (EPT) of viral RNA which differed from the others that widely prevailed on this farm. The VP7 amino acid sequence of strain CH3 also showed a high homology to that of G14 strain FI23, and the VP4 sequence, similar to that of strain H2, respectively. (2) Foal diarrhea with G3 RV broke out on the above-mentioned farm. In 1989, all of the foals received bovine colostral immunoglobulin (Ig) powder during the epidemic, and their morbidity was lower than that observed in 1987, when the Ig powder was not administered to foals. This suggests that the administration of Ig powder might partially prevent foal diarrhea. (3) Eight RV strains were isolated from fecal samples in epidemic diarrhea of new-born calves. Viral RNAs of the strains were classified into 5 EPTs. However, some strains presented not a single but mixed-up conformations of dual or triple EPTs. These data suggest that the mixed infection of distinct RVs in one calf cause the rearrengement of genomic segments among the strains. (4) In a closed dairy farm, bovine RV was isolated from 35 (16%) of 222 fecal specimens repeatedly collected from 59 calves born during the years 1990-93. The affected calves had IgA and IgG coproantibody levels much higher than those of normal calves 3 weeks old (P<0.05). Most of the 35 strains were isolated from calves aged 2 to 6