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SUMMARYThe involvement of lysosomes in infection by mouse hepatitis virus 3 (MHV3) was studied. L cells were infected with MHV3 in the presence of NH4C1 or chloroquine, weak bases which increase the intralysosomal pH and impair lysosomal functions. NH4CI significantly inhibited virus-induced cytopathic effects and MHV3 replication, but did not prevent the attachment of 3H-labelled virus. No inhibition of MHV3 replication by NHaC1 and chloroquine was observed when tysosomotropic agents were added later than 3 h post-infection, suggesting the direct involvement of lysosomes in release of the viral genome into cytoplasm. These results, together with the lack of antibody-mediated immune lysis of MHV3-infected cells, suggest that MHV3 entered cells by an endocytic pathway (viropexis) followed by internalization into cellular lysosomes.

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Analysis of trichothecene mycotoxins in dust samples from ventilation systems of office buildings was applied as a rapid and inexpensive method for the detection of mycotoxins. Dust samples from three different office spaces of the Montreal urban area, reportedly affected by the "sick buildings syndrome", were analysed by thin-layer chromatography (TLC). Positive colour reaction on TLC plates with 4-(p-nitrobenzyl) pyridine, specific for the 12,13-epoxy group in the trichothecene nucleus, was obtained for the extracts of 0.5- to 50-g dust samples. The dust samples contained at least four trichothecenes: T-2 toxin, diacetoxyscirpenol, roridine A and T-2 tetraol. The results were confirmed by high-performance liquid chromatography analysis. Screening of dust samples from air ventilation systems of reportedly affected buildings provided direct evidence of trichothecene mycotoxins, with the detection limit estimated as 0.4-4 ng/mg dust. Thus, the dust sample analysis is suggested as a rapid technique for detecting the presence of myotoxins in the dust of ventilation systems.

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