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Detection of cytomegalovirus antigen and antibodies in the urine of small infants and children.

The diagnostic efficacy of an enzyme immune assay to detect cytomegalovirus (CMV) antigen in the urine of infected infants and children was determined, and the effect that CMV-specific antibodies present in the urine have on the sensitivity of the test was ascertained. The antigen was detected in 84.4% of the CMV-culture-positive samples, while CMV-specific IgA was detected in 24% of CMV-culture-positive specimens. The absence of CMV-specific IgA correlated with detection of CMV antigen in the CMV-culture-positive urine specimens (p less than 0.05).

Antibodies, Viral↗

Topology of the components of the DNA packaging machinery in the phage phi29 prohead.

Chromosome condensation inside dsDNA viral particles is a complex process requiring the coordinated action of several viral components. The similarity of the process in different viral systems has led to the suggestion that there is a common underlying mechanism for DNA packaging, in which the portal vertex or connector plays a key role. We have studied the topology of the packaging machinery using a number of antibodies directed against different domains of the connector. The charged amino-terminal, the carboxyl-terminal, and the RNA binding domain are accessible areas in the connector assembled into the prohead, while the domains corresponding to the 12 large appendages of the connector are buried inside the prohead. Furthermore, while the antibodies against the carboxyl and amino-terminal do not affect the packaging reaction, incubation of proheads with antibodies against the RNA binding domain abolishes the packaging activity. The comparison of the three-dimensional reconstructions of bacteriophage phi29 proheads with proheads devoid of their specific pRNA by RNase treatment shows that this treatment removes structural elements of the distal vertex of the portal structure, suggesting that the pRNA required for packaging is located at the open gate of the channel in the narrow side of the connector.

Antibodies, Viral↗

Flexibility of the major antigenic loop of foot-and-mouth disease virus bound to a Fab fragment of a neutralising antibody: structure and neutralisation.

The interaction of foot-and-mouth disease virus (FMDV) serotype C (clone C-S8c1) with a strongly neutralising monoclonal antibody (MAb) 4C4 has been studied by combining data from cryoelectron microscopy and x-ray crystallography. The MAb 4C4 binds to the exposed flexible GH-loop of viral protein 1 (VP1), which appears to retain its flexibility, allowing movement of the bound Fab. This is in striking contrast to MAb SD6, which binds to the same GH-loop of VP1 but exhibits no movement of the bound Fab when observed under identical conditions. However, MAbs 4C4 and SD6 have very similar neutralisation characteristics. The known atomic structure of FMDV C-S8c1 and that of the 4C4 Fab cocrystallised with a synthetic peptide corresponding to the GH-loop of VP1 were fitted to the cryoelectron microscope density map. The best fit of the 4C4 Fab is compatible only with monovalent binding of the MAb in agreement with the neutralisation data on 4C4 MAbs, Fab2s, and Fabs. The position of the bound GH-loop is related to other known positions of this loop by a hinge rotation about the base of the loop. The 4C4 Fab appears to interact almost exclusively with the G-H loop of VP1, making no other contacts with the viral capsid.

Animals↗

Rabbit antibodies against the major internal protein of a retrovirus-like particle bind to epidermal cells in psoriatic skin. Brief report.

A rabbit antiserum against the major internal protein, p27, of a psoriasis associated retrovirus-like particle has been used in indirect fluorescence microscopy of biopsies from psoriatic skin. The analysis indicate expression of p27 antigen in epithelial cells in psoriatic lesions and in clinically uninvolved psoriatic skin. A reaction of the antiserum with dermal vessel walls in the lesion was also observed.

Animals↗

Three antibody molecules can bind simultaneously to each monomer of the tetramer of influenza virus neuraminidase and the trimer of influenza virus hemagglutinin.

Trimeric hemagglutinin and tetrameric neuraminidase molecules isolated from influenza virus bind an average of 9 and 13 molecules respectively of monovalent antibody fragments prepared from IgG isolated from polyclonal sera. In each case this represents an average of approximately three molecules of antibody binding to each protomer. Although there is compelling evidence for the presence of multiple adjacent and overlapping epitopes covering the surface of these two viral antigens, steric hindrance ensures that even under saturating conditions only three molecules of monovalent antibody fragments can be simultaneously accommodated on each monomer.

Animals↗

Measurement of antibody-mediated binding of human polymorphonuclear leukocytes to HSV-1 infected anchorage fibroblasts.

A method for the quantitation of effector cell binding to anchorage fibroblast monolayers infected with HSV-1 is described. Human peripheral blood polymorphonuclear leukocytes (PMN) as effector cells were labeled with chromium-51. Fetal human lung fibroblasts were grown to confluency in microtiter plates, infected with HSV-1 and loaded with anti-HSV antibody. The amount of radiolabeled PMN adhering to the monolayer was determined after appropriate incubation and washings. The effector binding assay was shown to be dependent on specific anti-HSV antibodies, antibody concentration, HSV viral expression, and inoculation time. This assay system is especially useful for the evaluation of effector to target cell conjugate formation when applied to anchorage target cells.

Antibodies, Viral↗

Detection of circulating immune complexes in pathological human sera.

The results of attempts to detect circulating immune complexes in sera by two methods are described. Both rely on the binding of the first complement component (C1) to the complex for its detection. The results, using these methods, of attempts to show which patients have complexes which contain nucleic acid and hence possibly viral antigens in the complexes are discussed. The anti-complementary complexes found in some patients seem to be associated with immune-complex vascular disease.

Adult↗

Antigen-antibody system associated with non-A, non-B hepatitis detected by indirect immunofluorescence.

Ten chimpanzees were infected with non-A, non-B hepatitis by inoculation of patient serum or serum from a chimpanzee previously inoculated with patient serum. Convalescent serum from one of them reacted, in indirect immunofluorescent tests, with some of the hepatocyte nuclei in sections of autologous liver biopsy specimens and specimens from eight of the other chimpanzees. Serum from a convalescent patient reacted in the same way. These positive sera did not react with liver sections from uninfected chimpanzees. No reaction with positive liver sections was given by serum from chimpanzees which were uninfected or had antibodies to hepatitis A or B antigens. These control results suggest that the antigen-antibody system detected has specificity for non-A, non-B hepatitis.

Animals↗

Feline infectious peritonitis. An immune-mediated coronaviral vasculitis.

Mainly through studies inducing experimental infection of susceptible cats, significant advances have recently been made in our understanding of the pathogenesis of FIP. Much of this knowledge should not presently be directly extrapolated to field cases of FIP, because the route of infection and challenge dose and strain of virus may be significantly different. Advances in the prevention and treatment of FIP will depend greatly on clarification of the exact nature of the several coronaviruses affecting cats and the role of cell-mediated immunity in resistance to FIPV.

Animals↗