BeAn 58058 virus (BAV) was isolated from an Oryzomis rodent in Brazil. BAV was shown to be antigenically related to another poxvirus also isolated in Brazil, the Cotia virus, but it remained ungrouped. Electron microscopy revealed that BAV has a typical poxvirus morphology. The Hind III DNA profile of BAV genome was similar with that of VV WR and Lister, but some differences in the profile were detected. We have also detected the presence of genes homologous to vaccinia virus (VV WR) genes in the genome of BAV. Genes related to vaccinia thymidine kinase (TK) gene and vaccinia growth factor (VGF) gene were found. The patterns of TK and VGF mRNA transcripts described for vaccinia virus infected cells were observed in BAV infected cells. Nucleotide sequence of BAV VGF homologous gene was similar to VV WR VGF sequences. This similarity was further seen when cross-hybridization of total genomes of BAV and VV was done. Polypeptide synthesis of BAV and vaccinia in infected cells also showed similar profiles. The genetic data was used to construct a phylogenetic tree where BAV and VV were placed at the same cluster. Based on our findings we propose that BAV is a vaccinia virus variant.

Until now the interferon-mediated 2'-5' adenine oligonucleotide inhibitors (2-5A) of cell-free protein synthesis have not been detected in intact cells. Here we report their natural occurrence in interferon-treated, EMC virus-infected mouse L cells in amounts consistent with the idea that they play a part in the inhibition of virus growth.

No abstract

Under optimal conditions which minimized the accumulation of extraneous proteins, interferon preparations were obtained in L cells containing from 2 × 10 4 to 5 × 10 4 units/mg of protein. The radiolabeled proteins were liberated simultaneously with interferon from cultures exposed to tritiated amino acids after viral stimulation and from corresponding controls, and were subsequently purified with the following results. Chromatography of interferon on carboxymethyl-Sephadex C-25 eliminated selectively unlabeled or poorly labeled proteins, resulting in a greater than sixfold increase in counts per minute per milligram of protein. Similarly purified control material harbored at least 12 times less tritium per milligram of protein than interferon, and the label was more diversely distributed among proteins of different molecular weights. On electrophoresis of interferon in polyacrylamide gels, labeled proteins were reduced further by a factor of at least 10 without loss in titer. Final purification was estimated at greater than 280-fold, representing a calculated specific activity of at least 1.4 × 10 7 units of interferon per milligram of protein.

No abstract

Temperature strongly influenced morphogenesis of intracellular trypomastigotes in cell culture infected with 2 different strains of T. cruzi. With the Gilmar strain the amastigote-to-trypomastigote differentiation readily occurred at 33 and 37 C, whereas the CL strain differentiation took place at 33C but was inhibited at 37 C. The possiblity of this selective thermosensitivity resulting from mutational adaptation of the parasite is discussed.

Inhibition of T. cruzi amastigote-trypomastigote differentiation in tissue culture at 37 C is a strain-dependent event. When eight T. cruzi strains were submitted to two environmental temperatures (33 and 37 C), the following patterns of differentiation were obtained: in three strains, transformation was inhibited at 37 C but readily occurred at 33 C; in three other strains differentiation took place at both temperatures; finally, in the two remaining strains, a partial inhibition was detected at 37 C. The authors discuss the meaning of this intraspecific variation and the possible relationship with the occurrence of temperature-sensitive mutants among protozoa.

No abstract