Virus

About: Virus is a research topic. Over the lifetime, 136914 publications have been published within this topic receiving 5209107 citations. The topic is also known as: infectious agent & viruses.

Acyclovir-resistant herpes simplex virus infections in patients with the acquired immunodeficiency syndrome.

Abstract: RECURRENT herpes simplex virus (HSV) infections are frequent in patients with the acquired immunodeficiency syndrome (AIDS). Although they are usually self-limiting in the normal host, such infecti...

Quantitative analysis of the human immunodeficiency virus type 1 (HIV-1)-specific cytotoxic T lymphocyte (CTL) response at different stages of HIV-1 infection: differential CTL responses to HIV-1 and Epstein-Barr virus in late disease.

Abstract: Major histocompatibility complex (MHC)-restricted cytotoxic T lymphocytes (CTL) are part of the cellular immune response to human persistent virus infections. Measurements of the frequency and specificity of human immunodeficiency virus type 1 (HIV-1)-specific CTL and their variation with time may indicate their relative importance in modulating the progression of HIV-1 infection. We have used limiting dilution analysis (LDA) to derive quantitative estimates of the frequency of HIV-1-specific CTL precursors in a cross-sectional study of 23 patients at different clinical stages of HIV-1 infection and to compare these with the frequency of CTL precursors specific for another persistent virus (Epstein-Barr virus [EBV]) in the same patients. Peripheral blood mononuclear cells (PBMC) were stimulated in vitro with autologous HIV-1-infected lymphoblasts and assayed for cytotoxicity in 51Cr release assays against autologous and MHC-mismatched lymphoblastoid B cells infected with recombinant vaccinia viruses expressing the three HIV-1 structural gene products. The frequency of MHC-restricted precursors was high in asymptomatic HIV-1-infected patients (env-specific CTL precursors up to 73/10(6) PBMC; gag-specific CTL precursors up to 488/10(6) PBMC), although the relative frequency against the different structural gene products varied from patient to patient. The HIV-1-specific CTL precursor frequency was reduced in patients who had more severe ( 400/microliters, at frequencies that are high compared with those reported for other persistent viruses. A CTL response directed against multiple protein antigens of HIV-1 may protect the patient against epitope variation. The fact that the EBV-specific CTL precursor frequencies were maintained in advanced HIV-1 infection suggests that there may be selective impairment of the HIV-1-specific CTL response associated with disease progression.

CD8-positive T lymphocytes specific for murine cytomegalovirus immediate-early antigens mediate protective immunity.

Abstract: We have shown in a murine model system for acute, lethal cytomegalovirus (CMV) disease in the immunocompromised natural host that control of virus multiplication in tissues, protection from virus-caused tissue destruction, and survival are mediated by virus-specific CD8+ CD4-T lymphocytes. Protection from a lethal course of disease did not result in a rapid establishment of virus latency, but led to a long-lasting, persistent state of infection. The CD8- CD4+ subset of T lymphocytes was not effective by itself in controlling murine CMV (MCMV) multiplication in tissue or essential for the protective function of the CD8+ CD4- effector cells. The antiviral efficacy of the purified CD8+ CD4- subset was not impaired by preincubation with fibroblasts that presented viral structural antigens, but was significantly reduced after depletion of effector cells specific for the nonstructural immediate-early antigens of MCMV, which are specified by the first among a multitude of viral genes expressed during MCMV replication in permissive cells. Thus, MCMV disease provides the first example of a role for nonstructural herpesvirus immediate-early antigens in protective immunity.

Neutralization of human T-lymphotropic virus type III by sera of AIDS and AIDS-risk patients.

Abstract: Human T-lymphotropic virus type III (LAV, HTLV-III) is aetiologically linked to acquired immune deficiency syndrome (AIDS) and persistent general lymphadenopathy (PGL). Specific radioimmunoassays (RIA), enzyme-linked assays, immunofluorescence assays (IFA) and immunoblotting techniques are being used widely to detect serum antibodies to HTLV-III in infected patients and in those at risk of infection. However, these assays do not functionally identify those antibodies that neutralize the infectivity of the virus. We have used three methods of titrating serum neutralizing factors: inhibition of syncytium induction, neutralization of envelope pseudotypes of vesicular stomatitis virus (VSV) and reduction of infectivity of HTLV-III for a cell line permissive to virus replication. We report here that sera from subjects in various disease categories possess only low-level neutralizing activity, even when antibodies to viral membrane antigens are present in high titre. Envelope pseudotypes prepared from four HTLV-III isolates made in three different countries are equally sensitive to neutralization by positive sera, including sera from patients yielding two of the virus isolates.

Neutralizing antibody response during acute and chronic hepatitis C virus infection

Abstract: Little is known about the role of Abs in determining the outcome of hepatitis C virus (HCV) infection. By using infectious retroviral pseudotypes bearing HCV glycoproteins, we measured neutralizing Ab (nAb) responses during acute and chronic HCV infection. In seven acutely infected health care workers, only two developed a nAb response that failed to associate with viral clearance. In contrast, the majority of chronically infected patients had nAbs. To determine the kinetics of strain-specific and crossreactive nAb emergence, we studied patient H, the source of the prototype genotype 1a H77 HCV strain. An early weak nAb response, specific for the autologous virus, was detected at seroconversion. However, neutralization of heterologous viruses was detected only between 33 and 111 weeks of infection. We also examined the development of nAbs in 10 chimpanzees infected with H77 clonal virus. No nAb responses were detected in three animals that cleared virus, whereas strain-specific nAbs were detected in six of the seven chronically infected animals after ≈50 weeks of infection. The delayed appearance of high titer crossreactive nAbs in chronically infected patients suggests that selective mechanism(s) may operate to prevent the appearance of these Abs during acute infection. The long-term persistence of these nAbs in chronically infected patients may regulate viral replication.