PERSISTENCE OF A SINGLE ELECTROPHEROTYPE AND SEROTYPE-(G6P5) OF BOVINE ROTAVIRUS IN CALVES ON A CLOSED DAIRY FARM FROM 1990 TO 1993

A virologic survey was conducted on calves with diarrhea associated wi th bovine rotavirus (BRV) on a closed dairy farm. The BRV was detected from 32 of 219 (14.6%) fecal specimens repeatedly collected from 56 c alves born during the years 1992-1993, regardless of whether they had diarrhea. Most of the 32 strains were isolated from fecal specimens ob tained from 2- to 6-week-old calves. After electrophoresis of double-s tranded viral RNA from the 32 strains, genomic RNA migration patterns were similar to those of the predominant BRV strains isolated at the s ame farm during the years 1990-1991. All representative strains were i dentified as G serotype 6 (G6) and P type 5 (P5) by results of the vir us-neutralization test and polymerase chain reaction procedure. Thus, BRV had no change in genomic RNA electropherotypes and serologic antig enicities in a closed dairy herd over a period of several years.