摘要:

ObjectivesWe investigated the ability of several human neutralizing monoclonal antibodies (mAbs), originally raised against human immunodeficiency virus (HIV) clade B isolates, to neutralize primary clade C isolates as single agents and in combination.Study Design/MethodsHIV clade C isolates from five different countries were tested for susceptibility to neutralization by anti–clade B mAbs in human peripheral blood mononuclear cells. Monoclonal antibody combinations were evaluated for possible synergy.ResultsAll 20 primary HIV clade C isolates could be neutralized 97.5% to 100% by a quadruple combination of mAbs IgG1b12, 2G12, 2F5, and 4E10. These mAbs recognized conserved epitopes and were highly synergistic, resulting in strong cross-clade neutralization.ConclusionsIn our previous experiment, a synergistic combination of human neutralizing mAbs protected all macaque neonates against oral challenge with a simian-human immunodeficiency virus encoding HIVenv. Together, our data suggest that passive immunization with currently available anti–clade B mAbs could play a role in preventing HIV clade C transmission through breastfeeding.

ISSN:1090-9508    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Viral FLICE-inhibitory proteins (v-FLIPs) encoded by several herpesviruses and poxviruses share the ability to inhibit apoptosis after engagement of death receptors. In the current article, we provide insights into the mechanisms by which the v-FLIP of human herpesvirus 8 (HHV-8) (also referred to as Kaposi's sarcoma–associated virus) protects cells from apoptosis after Fas-induced signaling. Using v-FLIP expression vectors, our results clearly show that HHV-8 v-FLIP reduces the cleavage of procaspase-8 into its active p18 and p10 protease subunits upon Fas-induced cell death. These results were confirmed by lower caspase-8 and caspase-3 protease activities in extracts of HeLa cells expressing HHV-8 v-FLIP. Coimmunoprecipitation studies further indicate that HHV-8 v-FLIP physically interacts with procaspase-8, but not with Fas-associated protein with death domain in the cellular cytoplasm. These results suggest that binding of HHV-8 v-FLIP to procaspase-8 affects the recruitment and the activation of the latter at the death-induced signaling complex, resulting in diminished apoptotic cascade initiation. Because cellular FLIP was recently reported to modulate promoter containing NF-kB motifs and that both HHV-8 and human immunodeficiency virus type 1 (HIV-1) can infect monocytes, we studied the effects of v-FLIP on HIV-1 gene expression. Cotransfection experiments indicated that v-FLIP expression is associated with activation of HIV long terminal repeats: events that were strictly dependent on the presence of NF-&kgr;B consensus elements. In conclusion, HHV-8 v-FLIP can possibly contribute to the pathogenesis of both HHV-8 and HIV-1 through impaired Fas-dependent killing of infected cells by cytotoxic T cells and through activation of HIV gene expression.

ISSN:1090-9508    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

ObjectivesHepatitis C virus (HCV) does not replicate in vitro, suggesting that cultured cells may lack factors that are essential for efficient use of HCV messenger RNAs (mRNAs). Here, we have studied the efficiency of HCV mRNA translation compared with translation of capped and polyadenylated mRNAs in human cells.Study Design/MethodsWe have generated noninfectious minivirus mRNAs from an infectious HCV genome. These mRNAs were transfected into human cells, and the translation efficiency was determined.ResultsHepatitis C virus mRNAs under control of the HCV internal ribosome entry site (IRES) were inefficiently translated compared with capped and polyadenylated mRNAs. Addition of a cap and a polyA tail on the HCV mRNAs revealed that these structures interacted with the hepatitis C IRES in a synergistic manner to load ribosomes onto the HCV mRNAs, thereby strongly enhancing translation. The positive effect of the cap and the polyA tail on initiation of translation at the initiator AUG embedded in the HCV IRES was the result of a discontinuous scanning, or shunting, mechanism.ConclusionsThe results demonstrated that recruitment of ribosomes to the HCV mRNAs was inefficient in dividing cultured cells. Factors that are necessary for efficient translation of the HCV mRNAs in hepatocytes may be absent or inactive in cultured cells. This may be one reason for the inefficient replication of the HCV in vitro.

ISSN:1090-9508    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

ObjectivesE7 is one of the oncoproteins encoded by human papillomavirus-16 (HPV-16), the major etiologic factor responsible for cervical cancer. Human papillomavirus-16–E7 expressed by human uterine cervix carcinoma cells is also released in the extracellular compartment where it induces immune suppression. We investigated whether E7 was also responsible for the enhanced endothelial adhesiveness required in cancer progression.Study Design/MethodsWe treated cervical microvascular endothelial cells (CrMVEn) and human umbilical vein endothelial cells (HUVEC) with E7, tumor necrosis factor-&agr; (TNF-&agr;), and hydrogen peroxide (H2O2) and measured the expression of E-selectin, intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) by fluorescent-activated cell sorter analysis.ResultsE7 strongly induced the expression of E-selectin, ICAM-1, and VCAM-1 in CrMVEn, but not in HUVEC. Tumor necrosis factor-&agr; further increased the endothelial expression of adhesion molecules in CrMVEn. Hydrogen peroxide pretreatment resulted in an enhanced ICAM-1 and a decreased E-selectin and VCAM-1 expression. We also show indirect effects when endothelial cells were stimulated with the supernatant of E7-pretreated macrophages.ConclusionsThese results show that HPV-16–E7 oncoprotein strongly induces adhesion molecules expression in organ-specific endothelial cells.

ISSN:1090-9508    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

ObjectivesTo investigate the expression of the open reading frame (ORF) 50 protein, a human herpesvirus 8 (HHV-8)–encoded immediate early protein, in HHV-8–associated diseases.Study Design/MethodsWe developed a rabbit anti-ORF50 protein polyclonal antibody, and investigated the ORF50 protein expression by immunohistochemistry using primary effusion lymphoma (PEL) cell lines and tissue sections of Kaposi's sarcoma (KS), HHV-8–associated solid lymphoma, and multicentric Castleman's disease (MCD).ResultsWestern blot analysis revealed that this antibody reacted with a 110-kd protein in the lysate of phorbolester-stimulated HHV-8–infected PEL cell lines. Immunohistochemistry revealed that a very small population of cells expressed the ORF50 protein in KS and HHV-8–associated solid lymphoma cells, and almost all these cells expressed HHV-8–encoded latency-associated nuclear antigen. The ORF50 protein expression was also rare in the cells of PEL cell lines, and the staining pattern was diffuse or dot-like in the nuclei, overlapping partially with that of promyelocytic leukemia protein. In MCD, however, the ORF50 protein was expressed in some cells of the mantle zone of the lymphoid follicle.ConclusionsThe ORF50 protein expression in vivo was considerably rare in KS, HHV-8–associated solid lymphoma, and PEL, but was more frequent in MCD. Rare expression of this transactivator protein in HHV-8–associated malignancies causes low expression levels of other lytic proteins and may play a role in the maintenance of the latent infection. This is the first report describing the expression of an immediate early protein of HHV-8 in cases of HHV-8–associated diseases.

ISSN:1090-9508    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

ObjectivesLassa fever virus (LAS) is transmitted to man by rodent carriers and is fatal in a third of untreated cases. Our goal is to provide immune protection from Lassa fever by mucosal vaccination.Study Design/MethodsMice were vaccinated intragastrically with control vectors or with vectors (vaccinia orSalmonella) expressing LAS nucleocapsid protein (NP). Mice were challenged intracranially with a lethal dose of the related arenavirus, lymphocytic choriomeningitis virus (LCMV), as a measure of the vaccine's ability to elicit cross-protection.ResultsSalmonellaand vaccinia vectors expressing LAS NP each protected a third of the mice from lethal challenge with LCMV. All mice vaccinated with a vector expressing LCMV NP were protected as expected.ConclusionsThe LAS recombinantSalmonellavector is comparable to the LAS recombinant vaccinia vector in its ability to cross-protect mice from lethal challenge. Nucleocapsid protein is an inadequate immunogen on its own, but provides sufficient cross-protection to make it a useful component of a broadly reactive arenavirus vaccine.

ISSN:1090-9508    

出版商:OVID    

年代:2001

数据来源: OVID

ISSN:1090-9508    

出版商:OVID    

年代:2001

数据来源: OVID

ISSN:1090-9508    

出版商:OVID    

年代:2001

数据来源: OVID