Prevalence of acute enteric viral pathogens in acquired immunodeficiency syndrome patients with diarrhea.

Diarrhea due to enteric pathogens is an important complication of advanced human immunodeficiency virus infection. Whereas numerous bacterial and parasitic agents have been implicated, the role of pathogenic enteric viruses is less clear. Stools from 153 human immunodeficiency virus seropositive men were tested by electrophoresis, enzyme-linked immunosorbent assay, and immune electron microscopy for the presence of rotaviruses (group A and non-group A), adenoviruses, and Norwalk agent.

Pertussis toxin S1 mutant with reduced enzyme activity and a conserved protective epitope.

Pertussis toxin (PTX) is a major virulence factor in whooping cough and can elicit protective antibodies. Amino acid residues 8 to 15 of PTX subunit S1 are important for the adenosine diphosphate-ribosyltransferase activity associated with the pathobiological effects of PTX. Furthermore, this region contains at least a portion of an epitope that elicits both toxin-neutralizing and protective antibody responses in mice.

Identification of a region in the S1 subunit of pertussis toxin that is required for enzymatic activity and that contributes to the formation of a neutralizing antigenic determinant.

The S1 subunit of pertussis toxin possesses two regions (homology boxes), each spanning 8 residues, that are nearly identical in sequence to similarly located regions in the enzymatically active A fragments of two other ADP-ribosylating toxins: cholera toxin and Escherichia coli heat-labile toxin. This observation suggests a functional role for one or both of these regions in enzymatic activity. We have examined the role of one of these regions, located near the amino terminus of the S1 subunit, by using a high-level recombinant expression system and progressive truncation of the gene sequence encoding the amino terminus of the molecule.

Infectious rotavirus enters cells by direct cell membrane penetration, not by endocytosis.

Rotaviruses are icosahedral viruses with a segmented, double-stranded RNA genome. They are the major cause of severe infantile infectious diarrhea. Rotavirus growth in tissue culture is markedly enhanced by pretreatment of virus with trypsin.