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Query: UNIPROT:Q96DT5 (SIV)
 2,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The envelope (Env) glycoproteins of human and simian immunodeficiency viruses (HIV and SIV) form noncovalently associated oligomers which mediate virus binding to the cell surface and fusion between the viral envelope and plasma membrane. A high-affinity interaction with CD4 is a critical step in this process. In this report, we show that Env protein dimers, but not monomers, can bind two CD4 molecules simultaneously. Multimeric CD4 binding may have important implications for Env protein-CD4 avidity, CD4-induced release of gp120, and subunit-subunit cooperativity during virus membrane fusion as well as for therapeutic strategies.
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PMID:Multimeric CD4 binding exhibited by human and simian immunodeficiency virus envelope protein dimers. 150 Dec 94

Molecularly cloned simian immunodeficiency viruses capable of inducing acute, fatal disease in pig-tailed macaques had been derived previously from a biological clone (bcl-3) of the PBj14 isolate of SIV from sooty mangabey monkeys (SIVsmmPBj14). The present study was undertaken in order to characterize virus from a second biological clone of SIVsmmPBj14, bcl-1, which fails to induce acute or fatal disease. Polymerase chain reaction was used to amplify 5' and 3' viral genome halves. The DNA sequence of two 3' halves was determined, and an infectious recombinant generated using a bcl-3-derived 5' half and a bcl-1-derived 3' half. Overall, bcl-1- and bcl-3-derived viruses displayed close homology, differing by a total of 2% at the DNA level and 1-6% at the amino acid level within the 8 open reading frames examined. In contrast to the bcl-3-derived viruses, the bcl-1-derived viruses encode a truncated transmembrane envelope glycoprotein. Another consistent difference was the presence of a 22 bp duplication in the U3 portion of the long terminal repeat (LTR) of bcl-3-derived viruses that includes the NF-kappa B transcriptional enhancer binding site. To assess the importance of this duplication, virus chimeras were generated which removed the duplication from the 3'-LTR or from both LTRs of a bcl-3 clone. The former virus was unstable, reacquiring the duplication through recombination with the 5' LTR. No consistent difference were observed, however, between viruses with or without the duplication in the in vitro studies conducted to date.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Molecular clones from a non-acutely pathogenic derivative of SIVsmmPBj14: characterization and comparison to acutely pathogenic clones. 150 26

To determine the viability of the immunodeficiency virus in the laser plume after carbon dioxide (CO2) laser irradiation, multiple samples of culture medium containing concentrated simian immunodeficiency virus (SIVMAC at 1000 TCID50 cultured from HUT 78 cells) were irradiated with a continuous-wave CO2 laser at variable irradiances (from 400 W/cm2 for 5 seconds to 1600 W/cm2 for 300 seconds). The resultant plume was collected and cultured for the presence of SIV. A positive control consisted of handling an infected specimen identically to the test specimens, with the exception of CO2 laser irradiation. All test cultures remained negative over an 8 week incubation period, while the control was positive for viable SIV within 7 days. These results suggest that SIV is not viable in the laser plume after CO2 laser irradiation. Further investigation is necessary before extrapolating these results to the human immunodeficiency virus (HIV).
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PMID:Analysis of the carbon dioxide laser plume for simian immunodeficiency virus. 156 Jan 53

Malignant lymphomas associated with human (HIV) and simian (SIV) immunodeficiency virus infections are reviewed and compared. Recent observation of a high frequency of lymphomas in a series of cynomolgus macaques, highly immunodeficient after infection with SIVsm(smm3) are described. In addition to the increased frequency in human and monkey AIDS, SIV and HIV lymphomas share several important features. Clinically and by histology they present as aggressive high-grade malignant tumors with a predilection for extranodal growth in viscera, skin, central nervous system, testis, and retroorbitally. Most malignant lymphomas are of B-cell origin. AIDS lymphomas in humans are heterogeneous with regard to Epstein-Barr virus (EBV) association. Similarly, most lymphomas in monkeys experimentally infected with SIV tested to date were shown to be associated with an EBV-like simian herpes virus. These observations point to the possibility of using SIV-immunodeficient macaques for study of EBV and other oncogenic and immunosuppressive factors in AIDS-associated lymphomagenesis.
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PMID:Malignant lymphoma associated with human AIDS and with SIV-induced immunodeficiency in macaques. 157 Nov 94

The transmission of human immunodeficiency virus (HIV-1) and other enveloped virus by blood transfusion is a major concern. Photosensitive dyes such as hematoporphyrin derivative (HPD), dihematoporphyrin ether (DHE), benzoporphyrin derivatives (BPD), extended ring porphyrins, sapphyrins and texaphyrins, and various cyanines were used with viral cultures to test the feasibility of using those light-excitable dyes to kill virus. A photodynamic flow cell was used to irradiate viral suspensions or viral infected cells in culture media or in whole blood. Herpes virus (HSV-1) was used to screen compounds. Effective compounds were subsequently tested for their ability to kill HIV-1, CMV, and SIV in culture medium and in blood and proved to effectively kill free virus and infected cells at significant viremias. Irradiation was achieved with a filtered xenon light source and/or tunable dye laser. Concentrations of dyes at 10 times viral kill dose were irradiated in blood which was tested for damage to erythrocytes (RBC), platelets, and blood proteins. No damage to RBC, complement factors, and immunoglobulins was evident immediately after photodynamic treatment. Platelet condition is minimally modified with time. Photodynamic treatment of blood appears to be a feasible means of eradicating virus and some protozoans from blood.
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PMID:Inactivation of viruses with photoactive compounds. 161 95

The promoter activity of long terminal repeats (LTRs) of four strains of the simian immunodeficiency virus isolated from African green monkeys (SIVAGM) was compared with those of various LTRs derived from the other representative primate lentiviruses: human immunodeficiency virus type 1 (HIV-1), type 2 (HIV-2), SIV from a rhesus monkey (SIVMAC), and SIV from a mandrill (SIVMND). The expression of the LTRs was evaluated by monitoring chloramphenicol acetyltransferase production after transfection of reporter plasmid clones. In the absence of viral tat, all SIVAGM LTRs acted as much more efficient promoters than any of the other LTRs. When tat gene products were supplied in trans, LTRs of SIVAGM and SIVMND were activated inefficiently relative to high responder LTRs of HIV-2 and SIVMAC. The LTR of HIV-1 was highly activated by HIV-1 tat, but not so much by HIV-2, SIVAGM, and SIVMND tat.
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PMID:Functional analysis of long terminal repeats derived from four strains of simian immunodeficiency virus SIVAGM in relation to other primate lentiviruses. 165 99

Although oncoviruses and lentiviruses replicate by similar mechanisms, they differ fundamentally in the usual fate of the infected host cell during productive natural infections. Oncoviruses typically establish persistent nonlytic infections in natural host cells, while lentivirus infections characteristically result in a variety of cytopathic effects ultimately leading to death of the target cell. Described here is a unique structural motif consisting of a strongly amphipathic and arginine-rich helical peptide segment in the carboxyl end of lentivirus TM proteins that is structurally similar to the family of cytolytic peptides produced as defensive agents by certain insects and amphibians. Also demonstrated is the lytic nature of synthetic peptides constructed from the transmembrane (TM) protein of human and simian immunodeficiency viruses (HIV and SIV). Thus, it appears that the cytopathic properties of lentiviruses may be in part attributed to the presence of lytic peptides within the TM protein, designated lentivirus lytic peptide (LLP) and that variations in this segment could account for some of the differences observed in the cytopathicity among variants of a particular lentivirus.
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PMID:A structural correlation between lentivirus transmembrane proteins and natural cytolytic peptides. 165 72

To develop a nonhuman primate model for maternal-fetal transmission of HIV infection, we have inoculated pregnant Macaca nemestrina with uncloned SIVMne. Three animals inoculated during the third trimester delivered healthy infants. One of the three infants, a male born 31 days after the mother was inoculated with SIV, became virus-positive but failed to produce SIV-specific antibody and died with overt simian immunodeficiency and disseminated adenovirus (SV20) infection at age six and one-half months. SIV and adenovirus antigen could be demonstrated by immunohistochemical methods in multiple organ systems.
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PMID:Maternal-fetal transmission of SIV in macaques: disseminated adenovirus infection in an offspring with congenital SIV infection. 165 26

RNA pseudoknot structural motifs could have implications for a wide range of biological processes of RNAs. In this study, the potential RNA pseudoknots just downstream from the known and suspected retroviral frame-shift sites were predicted in the Rous sarcoma virus, primate immunodeficiency viruses (HIV-1, HIV-2, and SIV), equine infectious anemia virus, visna virus, bovine leukemia virus, human T-cell leukemia virus (types I and II), mouse mammary tumor virus, Mason-Pfizer monkey virus, and simian SRV-1 type-D retrovirus. Also, the putative RNA pseudoknots were detected in the gag-pol overlaps of two retrotransposons of Drosophila, 17.6 and gypsy, and the mouse intracisternal A particle. For each sequence, the thermodynamic stability and statistical significance of the secondary structure involved in the predicted tertiary structure were assessed and compared. Our results show that the stem-loop structures in the pseudoknots are both thermodynamically highly stable and statistically significant relative to other such configurations that potentially occur in the gag-pol or gag-pro and pro-pol junction domains of these viruses (300 nucleotides upstream and downstream from the possible frameshift sites are included). Moreover, the structural features of the predicted pseudoknots following the frameshift site of pro-pol overlaps of the HTLV-1 and HTLV-2 retroviruses are structurally well conserved. The occurrence of eight compensatory base changes in the tertiary interaction of the two related sequences allow the conservation of their tertiary structures in spite of the sequence divergence. The results support the possible control mechanism for frameshifting proposed by Brierley et al. and Jacks et al.
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PMID:RNA pseudoknots downstream of the frameshift sites of retroviruses. 166 82

Experimental and clinical evidence indicates that all lentiviruses of animals and humans are neurotropic and potentially neurovirulent. The prototypic animal lentiviruses, visna virus in sheep and caprine arthritis encephalitis virus in goats have been known for decades to induce neurologic disease. More recently, infection of the brain with the human immunodeficiency virus (HIV) has been linked to an associated encephalopathy and cognitive/motor complex. While the visna virus and caprine arthritis encephalitis virus are important models of neurologic disease they are not optimal for the study of HIV encephalitis because immune deficiency is only a minor component of the disease they induce. By contrast, the recently isolated lentiviruses from monkeys and cats, the simian and feline immunodeficiency viruses (SIV and FIV respectively), are profoundly immunosuppressive as well as neurotropic. SIV infection of the central nervous system of macaques now provides the best animal model for HIV infection of the human brain due to the close evolutionary relationship between monkeys and man, the genetic relatedness of their respective lentiviruses, and the similarities in the neuropathology. This chapter will compare and contrast the neurobiology of SIV and FIV with HIV.
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PMID:Neurobiology of simian and feline immunodeficiency virus infections. 166 9


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