A lack of consistent amino acid substitutions in NSP4 between rotaviruses derived from diarrheal and asymptomatically-infected kittens.

Nonstructural glycoprotein NSP4 of group A rotavirus has recently been shown to be a viral enterotoxin, inducing diarrhea in neonatal mice. Literature is conflicting as to whether there is any consistent amino acid substitution between virulent (or symptomatic) and attenuated (or asymptomatic) rotavirus strains. We have sequenced and compared the NSP4 sequences derived from a total of 10 geographically- and serologically-related feline rotavirus strains from both diarrheal and asymptomatically-infected kittens. These NSP4 sequences were closely related to each other and there were differences at 19 amino acid residues, but none was segregated according to whether the strain was isolated from a diarrheal kitten or not. Thus, this study failed to lend support to the contention that mutations in NSP4 play a significant role in the pathogenesis of rotavirus diarrhea. Involvement of other genes may explain the outcome of infection in cats from which these 10 feline rotaviruses were isolated.