RESUMO
The use of a recently developed EIA using antisera raised against purified baculovirus expressed recombinant Mexico virus (rMx) capsid protein is described for screening for human calicivirus in stools. The results show that MX-like viruses have been circulating in the UK periodically since 1983 and were an occasional cause of sporadic cases of diarrhoea in infants and outbreaks of infection among elderly patients in hospitals and old people's homes. Further evidence is presented that some strains of caliciviruses with characteristic surface morphology (HuCVs) and some with an indistinct appearance, small round structured viruses (SRSVs) are antigenically related to MxV. Tests on SRSVs from four unrelated outbreaks typed as UK3 failed to react in the Mx EIA or recombinant Norwalk virus (rNV) EIA. A 2-month survey of 206 children treated in two London hospitals for diarrhoea showed that only one was positive for MxV, a child known to be infected with HIV-1. None of the samples reacted in the rNV EIA.
Assuntos
Infecções por Caliciviridae/virologia , Caliciviridae/isolamento & purificação , Diarreia/virologia , Adulto , Antígenos Virais/imunologia , Caliciviridae/imunologia , Caliciviridae/ultraestrutura , Infecções por Caliciviridae/epidemiologia , Infecções por Caliciviridae/imunologia , Capsídeo/imunologia , Criança , DNA Viral/análise , Diarreia/epidemiologia , Diarreia/imunologia , Surtos de Doenças , Humanos , México , Reino Unido/epidemiologiaRESUMO
The use of an enzyme immunoassay (EIA) employing a baculovirus-expressed recombinant human calicivirus (Mexico virus, MxV) for the detection of IgG-specific antibodies is described. MxV appeared to be related antigenically to a strain of small round structured virus, SRSV/UK4/Leeds/91, which had previously been shown by solid phase immune electron microscopy (SPIEM) to be related to Snow Mountain agent (SMA). One other outbreak which occurred in San Anita, USA in 1980 and was due to consumption of contaminated water was caused by a virus antigenically related to MxV. Volunteers and patients who developed significant IgG responses to rMxV showed anamnestic IgG responses (2 to 4-fold) in the recombinant Norwalk virus (rNV) IgG assay. Patients and volunteers who were known to have been infected with several other strains of calicivirus/small round spherical viruses (SRSV) including NV and SRSV UK3 showed no significant antibody response to rMxV in the EIA. A seroepidemiological survey of sera from 338 children in London showed that infection with MxV occurred earlier in life than NV. Primary infections with MxV were common after the age of 6 months. Over 70% of children had evidence of infection by the ages of 2 years, whereas only 12% of these children had been infected with NV. High concentrations of maternal antibody were present during the first month of life which was detected in 96% of the neonates. The results suggest that the high sensitivity of the EIA may be detecting maternal antibody throughout the first 8 months of life.