Interactions of a nonneutralizing IgM antibody and complement in parainfluenza virus neutralization.
Virology
; 167(2): 433-41, 1988 Dec.
Article
em En
| MEDLINE
| ID: mdl-2849234
ABSTRACT
While many viruses activate the complement cascade directly, this is generally not a neutralizing event in the absence of antibody. We used a nonneutralizing IgM monoclonal antibody to parainfluenza virus type 3 (PIV3) hemagglutinin-neuraminidase (HN) to explore the role of antibody in complement-dependent neutralization of PIV3. Neither the antibody nor nonimmune guinea pig serum (GPS) neutralized PIV3 significantly, but a more than 100-fold reduction in titer was found when antibody and GPS were combined. Heat-inactivated GPS or GPS lacking either of two different complement proteins were all inactive with or without antibody. Specific repletion of the deficient sera with highly purified complement proteins restored neutralizing activity, indicating an absolute requirement for the classical pathway of complement activation and lytic terminal complement components, and viral lysis was confirmed by electron microscopy. The presence of antibody before complement activation was essential; later addition had no effect. Spontaneous complement activation by PIV3 occurred via the classical pathway in the absence of antibody. Addition of antibody did not alter the overall rate or extent of complement component C3 binding to PIV3 in these experiments. We conclude that certain nonneutralizing antibodies may support complement-dependent PIV3 neutralization by facilitating viral lysis. This process does not, however, involve enhanced activation through the C3 step. Lysis may require antibody-dependent localization of the membrane attack complex or reorganization of the viral envelope structures to facilitate attack complex insertion and lysis.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas do Sistema Complemento
/
Imunoglobulina M
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Proteínas do Envelope Viral
/
Respirovirus
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Anticorpos Antivirais
Idioma:
En
Revista:
Virology
Ano de publicação:
1988
Tipo de documento:
Article