E. bieneusi is an important cause of chronic diarrhea in HIV-infected persons. This new diagnostic technique serves as a practical, noninvasive means to detect microsporidia spores in stool specimens and is also applicable to the examination of duodenal aspirates.

Increasing mortality in intravenous (IV) drug users not reported to surveillance as acquired immunodeficiency syndrome (AIDS) has occurred in New York City coincident with the AIDS epidemic. From 1981 to 1986, narcotics-related deaths increased on average 32% per year from 492 in 1981 to 1996 in 1986. This increase included deaths from AIDS increasing from 0 to 905 and deaths from other causes, many of which were infectious diseases, increasing from 492 to 1091. Investigations of these deaths suggest a causal association with human immunodeficiency virus (HIV) infection. These deaths may represent a spectrum of HIV-related disease that has not been identified through AIDS surveillance and has resulted in a large underestimation of the impact of AIDS on IV drug users and blacks and Hispanics.

Astroviruses are nonenveloped particles with a distinctive star-shaped surface structure that have been detected by electron microscopy in stool samples from humans and animals with gastroenteritis. We examined the patterns of macromolecular synthesis in astrovirus-infected cells with a goal of establishing a molecular basis for taxonomic classification. Trypsin is required for continuous replication of astrovirus in cultured cells; however, during a single cycle of infection, astrovirus antigen was synthesized earlier and at higher levels when serum, rather than trypsin, was included in the growth medium. This enhanced production of antigen, as measured by enzyme immunoassay, was accompanied by the appearance of aggregates of virus particles in the cytoplasm of infected cells. During astrovirus replication in cells cultured in the presence of serum, we detected a single infection-specific protein (90 kDa) beginning at 12 h postinfection. This protein was recognized by antiastrovirus rabbit serum and was sensitive to trypsin digestion in vitro, with the concomitant appearance of three smaller immunoreactive proteins (31, 29, and 20 kDa). We also detected two dactinomycin-resistant RNAs (7.2 and 2.8 kb), both of which were polyadenylated, in the cytoplasm of astrovirus-infected cells. The larger of these two RNAs is presumably the viral genome, whereas the smaller species may be a subgenomic messenger. Comparison of the proteins and RNAs synthesized in astrovirus-infected cells with those of the recognized families of nonenveloped single-stranded RNA animal viruses suggests that astroviruses should not be classified as members of either Caliciviridae or Picornaviridae.

Results of this study indicate that larger studies of antimycobacterial therapy of BU are warranted and can be successfully undertaken.

A benign small-plaque clone of Venezuelan equine encephalitis virus was efficiently removed from the blood of inoculated hamsters by adsorption to cells of the hepatic reticuloendothelial system. More than 99% of infectious small-plaque virus, intrinsically labeled with 32P, was cleared from the blood within 30 min of inoculation; 47.6% of the 32P-labeled small-plaque virus inoculum was concentrated in the liver. In contrast, only 0.8% of a virulent large-plaque clone of the virus was cleared from the blood. The affinity of small-plaque virus for liver tissue was confirmed by electron microscopy, since inoculated small-plaque virions were readily visualized in phagocytic vacuoles of hepatic endothelial and Kupffer cells, where they appeared to be undergoing degradation. In contrast, large-plaque virus was not visualized in the liver. A critical determinant of virulence for viruses that do not replicate in hepatic reticuloendothelial cells may be the efficiency with which they are removed from the blood by adsorption to such cells.