摘要:

We have analyzed viral DNA patterns, obtained following digestion of six different infectious bovine rhinotracheitis isolates, using a panel of restriction enzymes. Several differences in profiles were observed, particularly for a Canadian viral strain which presumably contained a genome that was larger than the other five infectious bovine rhinotracheitis genomes. Also, an insertion/deletion of a Hindlll restriction site was found in the DNA of a Danish strain; this additional Hindlll site was localized precisely within the original Hindlll E fragment of the infectious bovine rhinotracheitis virus. Interestingly, results could be used to distinguish each viral strain examined from the others by simple digestion with the appropriate enzyme.

ISSN:0300-5526    

DOI:10.1159/000150192

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

A variant of Sabin type 3 poliovirus, 265B, only produces 2–3% of the yields of control virus and has a protracted growth cycle in HeLa cells. Attachment and penetration do not appear to account for defective growth of 265B. Viral protein and RNA syntheses are reduced, and blockage of cell protein synthesis is delayed considerably as compared with the parent virus. Nucleotide sequence analysis failed to detect mutations in protein 2AProt or changes in the 5’-noncoding region that could account for growth properties of the virus. However, a Thr-to-Ala substitution was found in viral peptide 2B of 265B, and this alteration is probably responsible for the replication def

ISSN:0300-5526    

DOI:10.1159/000150193

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

Poliovirus infection of either undifferentiated or differentiated U937 cells produced a decrease in the percentage of cells positive for the surface expression of the CD4, CD11c, CD14, or 8E11 antigens. The number of 4F2 surface molecules per cell increased in infected normal U937 cells, but was unaffected in differentiated cells. The level of O–2 production in infected differentiated U937 cells was approximately 50% of that found when not infected. Finally, poliovirus RN A levels and infectious particle production were similar in either cell typ

ISSN:0300-5526    

DOI:10.1159/000150194

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

Synthetic oligodeoxynucleotide probes, 21–23 nucleotides in length, were prepared which specifically hybridize to the genomes of the wild type 1 and 3 polioviruses currently endemic to the northeastern region of Brazil. The probes are complementary to sequences near the 5’-terminus of the VPl gene that differ substantially among genetically distant polioviruses but are largely conserved among related isolates. The probes have been routinely used in the laboratory surveillance of poliomyelitis cases in Brazil, permitting direct, rapid identification of the indigenous wild polioviruses by dot-blot hybridizat

ISSN:0300-5526    

DOI:10.1159/000150195

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

In human immunodeficiency virus type 1 (HIV-1) infected individuals, the antibody response to the external envelope (gpl20) is associated with in vitro neutralization. To further characterize the anti-gpl20 response, we examined the IgG reactivity of 75 HIV-1-seroconverted and 200 HIV-1-seropositive individuals to deletion mutants of gpl20 in an enzyme immunoassay. We used yeast-derived, non-glycosylated recombinant HIV-1 SF2 gpl20 equivalent and-variants deleted in variable regions. We observed two distinctive response patterns: IgG non-responders (SF2-V3-restricted responders) and IgG responders to conserved regions of gpl20. This divergence in response pattern occurred soon after gag/env HIV-1 antibody seroconversion and persisted in time within an individual. In addition, the SF2-V3-restricted responders had a higher frequency of HIV-1 core antigen positivity and HIV-1 core antibody negativity than the non-restricted responders. These results suggest that specific and persistent host antibody response patterns to gpl20 develop early in HIV-1 infection and that these patterns are associated with differences in HIV-1 expression.

ISSN:0300-5526    

DOI:10.1159/000150196

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

The plasmid pSV3-neo that carries the SV40 early genetic region and the neor resistance gene underwent homologous recombination between SV40-duplicated sequences of the small t antigen intron and the polyadenylation site after transfection into rabbit vascular smooth muscle cells. This recombination yielded two free plasmids of 1.7 and 3.0 kb that replicated in transfected rabbit cells, while the vector plasmid did not. Replication of the two recombinant plasmids continued for several months in rabbit cells transformed by pSV3-neo, and their structure remained unchanged. Between 15 and 2,510 copies per cell of the 3.0-kb plasmid and between 370 and 1,565 copies per cell of the 1.7-kb plasmid were found in different pSV3-neo-transformed rabbit clones. Similar recombined plasmids were found 3 days after transfection of pSV3-neo onto SV40-transformed rabbit cells. By comparison, pSV3-neo was replicated in simian cells, but no recombined plasmids were detected by Southern analysis. No replication was detected after transfection of pSV3-neo into mouse cells. These results appear to reflect important differences between rabbit and simian cells in the efficiency of homologous recombination involving specific S V40 sequences and/or in the replication of the resulting recombinants. The role of the host cell in the evolution of SV40 sequences may influence the outcome of the infection with this virus.

ISSN:0300-5526    

DOI:10.1159/000150197

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

Abnormal tubulofilamentous particles were identified by electron microscopy using a simple touch negative staining technique from brains of mice infected with four strains of the scrapie agent. Treatment by three proteolytic enzymes and subsequent treatment with DNase and mung bean nuclease of grids prepared from the infected animals confirmed previous observations that the tubulofilamentous particles observed in scrapie-effected brains are complex structures. The core of the tubulofilamentous particle scrapie-associated fibrils was revealed by treatment with SDS. Treatment with proteolytic enzymes and subsequent treatment with DNase or mung bean nuclease or Si nuclease also revealed typical and transitional stages of scrapie-associated fibrils. However, treatment with RNase A had no effect. The data suggest that nucleic acid is a single-stranded DNA protected by a protein coat.

ISSN:0300-5526    

DOI:10.1159/000150198

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

The envelope glycoprotein G of the Indiana serotype of vesicular stomatitis virus was modified not only by palmitylation, but also by myristylation, both occurring at the carboxy-terminal segment. When infected Chinese hamster ovary cells were grown in medium containing [3H]-myristate, the G protein and Ga2, the membrane-anchoring fragment containing about 71 amino acids, were labeled. This was shown by immunoprecipitation of cell lysates or extracellular fractions of infected cultures. Thin-layer chromatography of the fatty acid fraction released from G by hydrochloride hydrolysis showed that myristate, per se, was bound to G. The sensitivity of the fatty acid linkage to KOH/methanol indicated that [3H]-myristate was linked to the protein via ester or thioester bond(s). In contrast, the G protein of New Jersey serotype was not myristylated.

ISSN:0300-5526    

DOI:10.1159/000150199

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

The structural variability of the external glycoproteins of primate immunodeficiency viruses, has, so far, been investigated exclusively by sequence comparison of the respective proviral genomes. We have examined the structural relationship amont the external glycoproteins from three specific human immunodeficiency viruses (HIF-1, HIV-2), three specific simian immunodeficiency viruses from macaques (SIVmac) and three specific SIV from African green monkeys (SIVagm) by peptide mapping. Differences among glycoproteins were most pronounced between HIV-1 and SIVmac, as well as HIV-2. Two specific glycoproteins from independent SIVagm isolates were closely related to HIV-1, whereas the glycoprotein from a third SIVagm isolate was more similar to those of SIVmac and HIV-2. Our analysis reflects the classification of primate immunodeficiency viruses into three groups, the HIV-2 and SIVmac viruses, the green monkey isolates and HIV-1.

ISSN:0300-5526    

DOI:10.1159/000150200

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

Measles virus (MV) replication in acutely infected human cells was markedly stimulated following exposure to guanosine 3’,5’-monophosphate (cyclic GMP). Addition of cyclic GMP to tissue culture fluids immediately following infection with the virus resulted in acceleration of virus-mediated cell fusion, increased synthesis of virus-specified proteins and a 50-fold increase in infectious particle production. No evidence of altered viral protein phosphorylation was found. The results suggest that cyclic GMP stimulates multiple stages of the MV replication cy

ISSN:0300-5526    

DOI:10.1159/000150201

出版商:S. Karger AG    

年代:1991

数据来源: Karger