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At least 91 records · Page 5Linked to original sources
PubMed1977

Temperature-sensitive mutants of measles virus produced from persistently infected HeLa cells.

A persistent infection with the Edmonston strain of measles virus was established in HeLa cells in the absence of measles virus antibody (HeLaPI cells). By hemadsorption or immunofluoresnce virtually 100 per cent of the cells possessed measles virus components. HeLaPI cells produced no interferon and were not resistant to superinfection with Newcastle disease virus. HeLaPI cells contained both smooth (15--18 nm) and rought (20--35 nm) nucleocapsids as detected by electron microscopy. The virus produced from the HeLaPI cells (MVPI) varied in titer between 1.5 X 10(2) and 5.5 X10(4) PFU/ml, had a smaller plque size and was more heat resistant than wild-type measles virus. MVPI was also found to be temperature-sensitive. The temperature-sensitivity of MVPI was determined by the efficiency of plaquing at 33 degrees and 39 degrees C in Vero cell monolayers. When HeLaPI cells were incubated at 33 degrees C, there was a 50-fold increase in virus production as well as a slight increase in the percentage of cells forming infectious centers compared to HeLaPI cells grown at 37 degrees C. MVPI readily established a persistent infection in HeLa cells which also rleased temperature-sensitive virus.

Antigens, Viral↗
PubMed1986

Detection of HTLV-III/LAV antigens in peripheral blood lymphocytes from patients with AIDS.

HTLV-III was searched for in frozen sections of peripheral blood lymphocytes obtained from AIDS patients by an immunofluorescence technique. Human IgG against HTLV-III/LAV and monoclonal antibodies against HTLV-III/LAV P 24 antigen, yielded a strong cytoplasmic fluorescence in frozen sections of the lymphocytes. Some cells containing HTLV-III antigens displayed multinucleated giant forms. They also reacted with monoclonal antibodies against helper/inducer T-cells (OKT4+), as demonstrated by direct double staining immunofluorescence. Similarly, complexes of immunoglobulins and C3 component of complement were also detected on HTLV-III/LAV Ag expressing lymphocytes. Immunofluorescence study of frozen sections of peripheral blood lymphocytes appeared to be a simple, fast and reliable method for detection of HTLV-III/LAV Ag in AIDS patients.

Acquired Immunodeficiency Syndrome↗
PubMed1980

Characterization of herpes simplex virus strains isolated from patients with various diseases.

Herpes simplex virus strains (HSV) were isolated from various herpetic diseases. These HSV-strains isolated in Bulgaria (687) and in other countries (13) were studied by the neutralization test using standard type specific rabbit antisera and human gamma globulin. The serotype distribution of all strains showed: HSV-1 = 323 strains, HSV-2 = 372 strains, 5 strains behaved antigenically intermediate. A close correlation between the serotype of the strains and the localization of the lesions was established. All but four strains (1.24 per cent) isolated from the head belong to HSV-1, and only six HSV-strains (1.9 per cent) from lesions with other localizations were not HSV-2. Within six months to 8 years 2 to 4 herpes strains were isolated repeatedly from 30 patients. In 23 of these cases they were identical and in the other they showed different biological (3) or antigenical (4) properties. The results suggest, that under natural conditions some HSV-intermediate strains may exist.

Antigens, Viral↗
PubMed1982

Zoster encephalitis. Isolation of virus and measurement of varicella-zoster-specific antibodies in cerebrospinal fluid.

Varicella-zoster virus (VZV) was isolated on two occasions from the cerebrospinal fluid of an elderly woman with encephalomyelitis complicating thoracic zoster. Antibodies to ZV-induced membrane antigen (FAMA) were present in cerebrospinal fluid in a titer of 1:64; serum antibodies were 64-fold higher. Further evidence for local antibody production was derived from simultaneous measurements of immunoglobulin G and albumin in cerebrospinal fluid and serum and calculation of a cerebrospinal fluid-IgG index.

Aged↗
PubMed1987

The fusion glycoprotein of Sendai virus: sequence analysis of an epitope involved in fusion and virus neutralization.

To localize the amino acid residues on the F glycoprotein that are involved in Sendai virus fusion and virus neutralization, an anti-F monoclonal antibody which inhibits these functions was used to select three antigenic variants. Sequence analysis of the entire F gene of the three variants identified a single mutation that was responsible for the loss of antibody binding. The mutation, a proline to glutamine substitution at residue 399, was at a position in the primary sequence far removed from the hydrophobic F1-NH2 terminus thought to be directly involved in fusion. A synthetic peptide, comprising amino acid sequences in the region of the mutation, bound to the antibody used to select the variants, suggesting that the site of mutation is also the site of antibody binding. This information suggests that in the three-dimensional structure of the F molecule the amino acid residues around proline 399 are located close to the F1-NH2 terminus, and that fusion is directly inhibited by antibody binding. Other less likely alternatives are discussed.

Amino Acid Sequence↗
PubMed1986

The T4 gene encodes the AIDS virus receptor and is expressed in the immune system and the brain.

The isolation of clones encoding the human surface protein T4, and the expression of the T4 gene in new cellular environments, have enabled us to examine the role of this protein in the pathogenesis of AIDS. Our studies support a mechanism of AIDS virus infection that initially involves the specific interaction of the AIDS virus with T4 molecules on the cell surface. This association can be demonstrated on T4+ transformed T and B lymphocytes as well as epithelial cells. Furthermore, the presence of T4 on the surface of all human cells examined is sufficient to render these cells susceptible to AIDS virus infection. Our data suggest that the T4-AIDS virus complex is then internalized by receptor-mediated endocytosis. Finally, we find that the T4 gene is expressed in the brain as well as in lymphoid cells, providing an explanation for the dual neurotropic and lymphotropic character of the AIDS virus. In this manner, a T lymphocyte surface protein important in mediating effector cell-target cell interactions has been exploited by a human retrovirus to specifically target the AIDS virus to populations of T4+ cells.

Ammonium Chloride↗
PubMed1992

A novel, spectrophotometric microneutralization assay for respiratory syncytial virus.

We describe a simple and rapid microneutralization assay for respiratory syncytial virus (RSV) based on the colorimetric quantitation of the conversion of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) to a formazan product by the mitochondria of viable cells. Conditions for RSV infectivity were first optimized for sensitivity and reproducibility based on cell density and on RSV concentration as a function of multiplicity of infection (MOI) and time post-infection and the resulting optical densities were shown to be inversely proportional to MOI. For RSV neutralization, dilutions of heat-inactivated human plasma were preincubated with RSV and complement prior to infection of cells in microtiter plates. Following MTT dye conversion, 50% RSV neutralization titers were determined by linear regression analysis of the optical density values and endpoints were markedly influenced by MOI. The MTT-based assay was shown to be comparably sensitive to the plaque reduction assay for quantitation of neutralizing antibody, but more readily adaptable to the screening of a large number of samples. Finally, we demonstrated that the MTT microneutralization assay for RSV was useful for quantitation assay of neutralization activity in sera of mice and cotton rats.

Adult↗
PubMed1992

Generation of macaque B lymphoblastoid cell lines with simian Epstein-Barr-like viruses: transformation procedure, characterization of the cell lines and occurrence of simian foamy virus.

Two simian Epstein-Barr-like viruses, a rhesus Epstein-Barr virus and Herpesvirus papio, were used to transform B cells from rhesus or cynomolgus macaques. The resulting cell lines exhibited predominantly a B lymphocyte phenotype and expressed Epstein-Barr virus antigens. The majority of B lymphoblastoid cell lines from macaques, which were seropositive for simian foamy virus, developed giant cells in culture. The cytopathic agent was identified as a foamy virus and was transmissible to human embryonal fibroblasts. Treatment of cell cultures with AZT abolished giant cell formation.

Animals↗
PubMed1986

Maternally derived measles immunity in era of vaccine-protected mothers.

Measles hemagglutinin-inhibiting and neutralizing antibody titers are lower in women young enough to have been immunized by vaccination than in older women. In the children of both young and older mothers the antibody is concentrated 1.7-fold across the placenta, and the child's initial titer remains proportional to that of its mother. The transferred antibody is diluted by the baby's growth and degraded with a mean half-life of 48 days. By 8 1/2 months of age, 95% of the children of the mothers born since 1963 would have become susceptible to measles and responsive to immunization; the same level of susceptibility is not reached by children of mothers born before 1958 until 11 1/2 months of age. Among the offspring of younger mothers, a small group remains, about 2% of the total, with titers high enough to provide protection for 12 months, and these children would be poorly served if the age for vaccination were reduced for all. However, selective early vaccination of children of young mothers who have low antibody titers would eliminate an important focus of measles susceptibility.

Adolescent↗
PubMed2002

Immunity, immunopathology and vaccines against HIV?

Immunity and immunopathology of HIV infections leading to AIDS are reviewed from an evolutionary point of view. Accordingly infectious agents and host defences have co-evolved to reach balanced states where virus and host survive. While HIV has not quite yet reached an optimal balance, tuberculosis (TB), leprosy, HBV, HCV in humans or lymphocytic choriomeningitis virus (LCMV) in mice have successfully established persistence. These non- or poorly-cytopathic infections infect the next host usually before or at birth while hosts are immunoincompetent. They also infect immunocompetent hosts to persist at low levels concomitant with an ongoing T and B cell immune response that is repeatedly triggered by latent or persistent infection of extralymphatic or lymphatic host cells. This infectious or infection-immunity is the basis for cellular immunoprotection by antigen activated T cells. Because we cannot imitate this infection-immunity long-term and cannot build polyspecific vaccine combinations covering all possible neutralising variants yet, vaccines against TB, leprosy, HCV and HIV only protect transiently and incompletely.

AIDS Vaccines↗
PubMed2003

Equine infectious anemia in mules: virus isolation and pathogenicity studies.

There appears to be a lack of information concerning responses of mules to natural infection or experimental inoculation with equine infectious anemia virus (EIAV). In the present study EIAV was isolated from mules, for the first time, and its pathogenicity in naturally infected and experimentally inoculated animals was investigated. Two naturally infected (A and B) and three EIAV free mules (C, D and E) were used for this purpose. Mule A developed clinical signs, whereas mule B remained asymptomatic until the end of the study. Mules C and D were each inoculated with 10ml of blood from mule A and developed signs of the disease; they were euthanatized or died at day 22 and 25 post-inoculation, respectively. Mule E served as a negative control. The virus was isolated from the plasma samples of mules with clinical signs of the disease (A, C and D), but not from the asymptomatic mule B. Both proviral DNA and viral RNA were amplified from blood and tissues of the infected animals by nested polymerase chain reaction (nPCR). Antibodies were not detected in the two experimentally infected mules until their natural death or euthanasia. Clinicopathological and laboratory findings showed that, in mules, EIAV produced clinical signs similar to those observed in horses and ponies. Nested PCR proved to be a rapid, sensitive and specific diagnostic method for the detection of EIAV, regardless of the disease stage.

Animals↗
PubMed1997

Evaluation of the presence of porcine reproductive and respiratory syndrome virus in packaged pig meat using virus isolation and polymerase chain reaction (PCR) method.

An investigation was carried out to assess the potential presence of porcine reproductive and respiratory syndrome virus (PRRSV) in packaged pig meat. Samples of meat were collected at the processing plants and were sent to the laboratory for testing by virus isolation and reverse transcription-polymerase chain reaction (RT-PCR). Samples collected at four plants were randomly selected from lots of packaged pig meat from different slaughtering days and were sent frozen to the laboratory. Homogenates of meat were prepared and were inoculated onto MARC-145 cells and after two passages the presence of PRRSV was monitored by indirect immunofluorescence staining using PRRSV specific monoclonal antibody. All pig meat samples (six pools of meat samples from 73 different lots = 438 total homogenates) tested were found negative by virus isolation. Primers from open reading frames 6 and 7 were designed and a RT-PCR assay was developed and was demonstrated to detect both North American and European PRRSV isolates. Using this assay virus was detected at a concentration as low as 0.355 infectious virions per ml in supernatant of PRRSV infected cells. This RT-PCR assay could detect PRRS viral nucleic acid from various tissue samples of experimentally infected pigs including muscle tissue, thus demonstrating its applicability on tissue samples. All meat sample homogenates tested by RT-PCR (one sample pool from the 73 lots) were also found negative for PRRS viral nucleic acid. The results suggest that pig meat does not retain detectable amounts of PRRSV and further support that the transmission of PRRSV through pig meat is unlikely.

Abattoirs↗