Genomic variation in rotaviruses

The rotaviruses are a recently defined ubiquitous group of viruses responsible for causing acute-gastroenteritis in human infants and young animals. Biochemical studies have shown that the rotavirus genome consists of 11 segments of double-stranded RNA (dsRNA). This thesis concerns an investigation of the nature and extent of genomic variation in rötaviruses. A rapid and sensitive method for analyzing the genome profiles of rotavirus field isolates was developed. This is based on the direct extraction of dsRNA from faecal samples followed by radiolabelling with [32P3 pCp using T4 RNA ligase. This procedure has been further developed to produce a method for generating diagnostic fingerprints from individual species of dsRNA. A detailed structural study making use of this fingerprinting method has been undertaken on bovine, porcine and human rotavirus isolates. These analyses show that genome segment mobility variations are always associated with detectable changes in nucleotide sequence. They also show that corresponding genome segments with no mobility variation can have sequence-changes at least as great as those found in segments showing electrophoretic mobility variation. These results also revealed evidence for genome segment specific regions of terminal sequence conservation. Evidence for the occurrence of genome segment reassortment between viruses in the field was obtained. Finally evidence for the existence of a 'new' porcine rotavirus which is antigenically unrelated to previously described rotaviruses and has an unusual pattern for it's 11 genome segments is presented