Fluorescent in situ hybridization (FISH) – using mouse chromosome paints, probes for the mouse major centromeric satellite DNA, and probes for genes on chromosomes (Chr) 16 and 17 – was employed to locate the breakpoint in a translocation used to produce a mouse model for Down syndrome. The Ts65Dn trisomy is derived from the reciprocal translocation T(16;17)65Dn. The Ts65Dn mouse carries a marker chromosome containing the distal segment of Chr 16, a region that shows linkage conservation with human Chr 21, and the proximal end of Chr 17. This chromosome confers trisomy for most of the genes in the Chr 16 segment and Ts65Dn mice show many of the phenotypic features characteristic of Down syndrome. We used FISH on metaphase chromosomes from translocation T65Dn/+ heterozygotes and Ts65Dn mice to show that the Chr 17 breakpoint is distal to the heterochromatin of Chr 17, that the Ts65Dn marker chromosome contains a small portion of Chr 17 euchromatin, that the Chr 16 breakpoint lies between the Ncam2 and Gabpa/App genes, and that the Ts65Dn chromosome contains >80% of the human Chr 21 homologs. The significance of this finding is discussed in terms of the utility of this mouse model.

Studies were performed to evaluate the potential use of the bovine RIT 4237 rotavirus strain as a vaccine candidate against infection with human rotaviruses. Initial experiments revealed that colostrum-deprived piglets were susceptible to infection with several human strains, except for those belonging to subgroup 1. Subsequently, different immunization procedures with RIT 4237 were studied in this animal model. It was found that a two-dose administration, either given intramuscularly (twice) or once intramuscularly and once intragastrically, was necessary to induce a significant serum antibody response. Finally, the protective effect of the latter vaccination schedules against subgroup 2 and 3 rotavirus strains of human origin was evaluated by artificial challenge. In both cases, prior administration of live RIT 4237 significantly decreased fecal shedding of the challenge virus when compared with control animals.

The relative prevalence of human rotavirus subgroups was studied during a 3-year period (1978-1981) by means of a sensitive complement fixation technique. Among 93 rotavirus isolates from children with acute gastroenteritis in Brussels, the prevalence of subgroups 1, 2, and 3 was, respectively 24, 17, and 32%. The remaining 27% of strains could not be typed, but no evidence for the existence of any new subgroup was found. The proportion of strains belonging to the different subgroups remained roughly constant during the study period, showing the simultaneous occurrence of the various subgroups of viruses, even during the annual winter peak of rotavirus gastroenteritis.

No abstract

SUMMARY Electron microscopy, immune electron microscopy, and complement fixation as methods of detecting rotavirus in the stools of young children with gastroenteritis were compared in a blind study during the winter of 1975-6. Complement fixation was the simplest to perform, was as sensitive as the other two, and allowed a quantitative measurement of viral excretion. Absorption of faecal extracts with fetal calf serum usually removed the anticomplementary activity of faecal extracts.Bishop et al. Flewett et al. (1973) found reovirus-like particles (RVL) in both the duodenal mucosa and stools of children with acute gastroenteritis. Since then many others (Cruickshank et al., 1974;Holmes et al., 1974;Kapikian et al., 1974;Middleton et al., 1974;0rstavik et al., 1974;Tan et al., 1974;White et al., 1974; Conklin et al., 1975;Konno et al., 1975;Schoub et al., 1975;Zissis and De Kegel, 1975) have associated these particles with infantile gastroenteritis and variously named them rotavirus, duovirus, reovirus-like (RVL) particles, and infantile gastroenteritis virus (IGV).Whatever the name, there is no longer any doubt that this is a cosmopolitan virus causing localised epidemics in winter. It is now considered to be one of the major causes of non-bacterial gastroenteritis in children under 5 years, but it occasionally infects older children (Hara et al., 1976) and even adults (Gomez-Baretto et al., 1975;Zissis et al., 1976).Unfortunately no one has yet obtained a cytopathic effect on cell culture with human rotavirus. Therefore the diagnosis of diarrhoea caused by it relies generally on electron microscopy (EM, negative contrast). This is certainly not a routine procedure and could be used only in research laboratories.