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Biomedical subjects

P Albrecht

Publications and source records attributed to P Albrecht.

At least 127 records · Page 7Linked to original sources
PubMed1978

Sensitive neutralization test for virus antibody. 1. Mumps antibody.

A sensitive mumps virus plaque neutralization test has been developed based on the potentiation of virus-antibody complexes by heterologous anti-immunoglobulins (AIG). The enhanced neutralization test was approximately 100 times more sensitive than the conventional neutralization test or the hemagglutination-inhibition test. Using AIG against human immunoglobulin G (IgG) or human IgM permitted determination of the relative titers of the two classes of mumps antibody. The test does not require special equipment or expertise and can be readily introduced in virological laboratories.

Antibodies, Anti-Idiotypic↗
PubMed1978

Host defense mechanisms against influenza virus: interaction of influenza virus with murine macrophages in vitro.

The interaction of mouse macrophages with influenza virus was examined as part of a study into the defense mechanisms against influenza infection. Macrophages exposed to A/Port Chalmers/1/73 virus produced infectious foci on susceptible indicator cell monolayers. Sampling of supernatant fluids and cells from infected macrophage cultures showed release of virus adsorbed to the cell surface. Active virus replication in macrophages could not be demonstrated. Exposing macrophages to specific antibody before or after virus infection resulted in a significant decrease in the number of infectious macrophages. The results suggest that although macrophages are not the source of replicating influenza virus, they are able to spread the infection by having virus attaching to their surface. This activity is interfered with by the presence of specific antibody.

Animals↗
PubMed1978

Characterization of an RNA-dependent RNA polymerase activity associated with measles virus.

An RNA-dependent RNA polymerase activity has been found copurifying with measles virus infectivity and complement-fixing antigen in three Vero cell-grown variants of measles virus: the attenuated Edmonston B strain, the natural non-attenuated Edmonston strain, and a subacute sclerosing panencephalitis isolate, IP-3. Incubation of purified measles virions with immunoglobulin G derived from sera of monkeys hyperimmunized against measles specifically removes activity sedimenting in the density region of measles virions. The requirements of the reaction, which is RNase sensitive, are similar to those reported for other paramyxovirus-associated activities, including detergent, divalent cation, ribonucleoside triphosphates, and a reducing agent. The size classes of RNA synthesized correspond to those found in measles-infected cells, including 50, 35, and 16 to 20S. The product RNA of the Edmonston B virus-stimulated reaction was rendered RNase resistant by annealing with RNA extracted from purified Edmonston B virions. RNA from uninfected Vero cells was ineffective in the annealing reaction.

Antigen-Antibody Reactions↗
PubMed1977

Subacute sclerosing panencephalitis: experimental infection in primates.

Measles virus isolated from the brain of a 12-year-old boy with subacute sclerosing panencephalitis caused a chronic, progressive encephalitis in experimentally infected rhesus monkeys. The infection was eventually fatal in spite of pre-existing measles immunity and a vigorous secondary antibody response in serum and cerebrospinal fluid of the infected animals. The findings provide a basis for studies into the pathogenesis and possible treatment of the human disease.

Animals↗
PubMed1977

Persistence of maternal antibody in infants beyond 12 months: mechanism of measles vaccine failure.

A serologic study was made in 34 children immunized against measles at the age of 12 months. Using a sensitive virus neutralization test, it was found that many of the children had pre-existing maternal antibody to measles virus. Children with high pre-existing antibody titers failed to seroconvert. Children with lower pre-existing antibody titers seroconverted, but the resulting antibody titer was significantly lower than in children without pre-existing antibody titer. The results of this study demonstrate a probably mechanism for measles vaccine failure in 12-month-old children and support the recommendation of the Public Health Service Advisory Committee on Immunization Practices to postpone measles vaccination to 15 months of age.

Age Factors↗
PubMed1977

Immune responses during measles infection in immunosuppressed Rhesus monkeys.

Rhesus monkeys immunosuppressed with horse anti-human thymocyte gamma-globulin (ATG) were infected with measles and simultaneously inoculated with sheep erythrocytes (SRBC), a thymus-dependent antigen, and with pneumococcal polysaccaride type III (SSS-III), a thymus-independent antigen. ATG treatment alone suppressed SRBC antibody production, had no effect on SSS-III antibody production, and effectively eliminated circulating T cells compared to nonsuppressed monkeys. ATG treatment of measles-infected monkeys resulted in delayed virus clearance and delayed antibody production compared to nonsuppressed infected monkeys. After cessation of ATG treatment, measles antibodies and T cells reached normal levels, and measles virus was eliminated. Thus, immune clearance of measles virus is T cell-dependent, but the relative roles of cellular- and humoral-mediated immunity in vivo could not be clearly separated. Also, measles infection was associated with a decreased T cell mitogen responsiveness of circulating lymphocytes but not of lymph node lymphocytes, suggesting an altered circulating pattern of the cells responsible for delayed hypersensitivity. Also, measles infection had no effect on T-dependent antibody production to SRBC.

Animals↗
PubMed1976

Cytolytic, complement-dependent antibodies to measles virus in rhesus monkeys after administration of live or killed virus.

Infection of rhesus monkeys with measles virus induced specific complement-dependent cytolytic antibodies during the early phase of acute infection. The development of maximal levels of the complement-dependent cytolytic antibodies appears to be dependent on the respiratory rather than the parenteral route of infection and on the use of live rather than killed measles virus. These levels of cytolytic antibodies seem to be independent of levels of simultaneously developing neutralizing and hemagglutinating antibodies. It is proposed that complement-dependent cytolytic antibodies play an important role in the elimination of acute measles virus in vivo by lysing the foci of infected cells and by blocking the spread of virus by cell fusion.

Animals↗
PubMed1976

Acute and chronic infection of human lymphoblastoid cell lines with measles virus.

Several human continuous lymphoblastoid cell lines (LCL) having T or B characteristics were infected with low and high passage strains of measles virus. All of the cell lines were susceptible to one or the other or to both strains of measles virus with the production of typical syncytial giant cells and released cell-free infectious virus into the supernatant medium. There was no consistent pattern of susceptibility of LCL with either T or B characteristics to infection by measles virus. Viral induced cytolysis of the lymphoblastoid cells in many of the lines was marked, but in the LCL that could be maintained over longer periods of time, a state of chronic, less cytolytic and persistent infection could be established. The infection was characterized by the production of moderate amounts of cell-free infectious virus for up to 4 1/2 months after initial infection with little change in the number of viable cells in culture. Long-term low multiplicity of infection (MOI) experiments demonstrated that the cell-free infectious virus was being produced only by a small number of cells, but the majority of cells in culture contained measles antigen that was in a cell-restricted, noninfectious, or defective form. Electron microscopic examination of the chronically infected cells demonstrated that many of them contained aggregates of hollow tubular intranuclear nucleocapsids whose "stripped" appearance was in marked contrast to the larger granular intracytoplasmic nucleocapsids found during earlier stages of infection. It is theorized that the persistent infection of LCL may serve as a model in understanding the immune mechanisms which permit latent and chronic measles infection in man.

Acute Disease↗
PubMed1976

Analysis of complement-dependent antibody-mediated lysis of target cells acutely infected with measles.

A sensitive assay for the detection of complement-dependent cytolytic measles-antibodies in monkey and human sera is described. The high sensitivity of the technique is dependent upon the use of Vero or MA-104 cells acutely infected with a high-titered, non-syncitiogenic strain of attenuated measles virus. Cytolytic antibody titers of serum can be determined either by endpoint dilution in the presence of a standard dilution of heterologous (guinea pig) complement or by percentage of lysis of a specific number of target cells at a standard dilution of immune serum (1:32). The latter technique proved expedient in the comparison of cytolytic activities of large numbers of serum samples. Clearly, the alternative complement pathway is effective in lysis of these cells, but neither the classical nor the alternative pathway alone appears to be as effective as both pathways combined. No prozone effect occurred with homologous complement, and inhibition of lysis was eliminated by washing sensitized cells before addition of heterologous complement. Lysis of measles-infected cells untreated with measles antibody occurred in the presence of both normal and C4-deficient guinea pig serum at high concentrations, but no such activity occurred with non-immune human or rhesus serum. Antibody-mediated complement-dependent lysis of measles-infected cells may be an important immune defense against acute measles infection.

Animals↗
PubMed1975

Measles infection of human mononuclear cells. I. Acute infection of peripheral blood lymphocytes and monocytes.

A study of the susceptibility of human peripheral blood mononuclear cells to measles virus infection and replication is reported. Resting lymphocytes obtained from adults showed very low levels of infection and virus replication while lymphocytes activated by plant mitogens or allogenic lymphocytes supported mononuclear cells obtained from the umbilical cord of healthy neonates were more susceptible to measles virus infection than those of adults; however, activated cord lymphocytes supported viral replication in the range observed with adult activated lymphocytes. Monocytes obtained from adults were relatively resistant to measles virus infection and replication while neonatal cord blood monocytes supported viral replication to the degree observed with activated lymphocytes. It is hypothesized that infection of acitivated lymphocytes may explain the depression of cell-mediated immunity seen during acute measles virus infection. The significance of the finding that neonatal monocytes are more susceptible to viral infection and replication than adult monocytes is discussed.

Adult↗
PubMed1975

Inhibition of lymphocyte stimulation by measles virus.

The effect of measles virus on phytohemagglutinin-(PHA) induced stimulation of human peripheral blood mononuclear cells was investigated to delineate possible mechanisms for viral suppression of cell-mediated immunity (CMI). it was noted that medium which had several days contact with uninfected monolayers as well as unpurified measles virus preparations produced significant inhibition of 3H-thymidine incorporation by PHA-stimulated lymphocytes. When partially purified measles virus preparations were used, however, marked inhibition was observed and the inhibitory effect of cell-derived factors could be separated easily from the virus-induced inhibition. Experiments to determine the mechanisms of this virus-induced inhibition of 3H-thymidine incorporation showed the following: 1) live measles virus and not UV-irradiated or heat-inactivated virus produced inhibition; 2) the inhibitory effect observed was not the result of a viral-induced inhibitor being released from measles-infected lymphocytes; and 3) monocyte depletion had no effect on the ability of measles virus to inhibit 3H-thymide incorporation by PHA-stimulated lymphocytes. Since it was found that measles virus-infected lymphocytes display an impaired response to in vitro PHA stimulation, perhaps this dysfunction may be extended to mediator release and other functions associated with delayed cutaneous hypersensitivity (DCH) in vivo.

Animals↗