- Email: [email protected]
A strain-specific domain in the HN glycoprotein of Newcastle disease virus
MECRANISMS OF NEUTRALIZATION POLY MERE ANTIBODIRS
OF INFLUENZA VIRUS BY MONOMERIC AND
HOWARD P. TAYLOR and NIGEL J. DIMMOCK, Department University of Warwick, Coventry CV4 ‘7AL, England.
of Biological
115a
Sciences,
The mechanism of neutralization of influenza virus (Fowl plague virus/Restock/34 H7Nl) depended on the character of the neutralizing antibody. When neutralized by either IgG or monomeric IgA virus attached to and penetrated BHK-21 cells from 4OC to 25OC This indicated that at a rate indistinguishable from that of non-neutralized virus. neutralizing monomeric IgA and IgG must have exerted an effect at a stage later than penetration. In contrast both neutralizing Considering the attachment. and pentameric respectively) However, at 25°C and 37OC None of this attached virus and sIgA interfered with the
A STRAIN-SPECIFIC
secretory IgA (sIgA) and IgM at 4OC completely blocked large molecular structures of these antibodies (dimeric neutralization is probably mediated by steric hindrance. neutralizing sIgA and IgM inhibited attachment by 50%. was internalized. Therefore at these temperatures IgM endocytic event responsible for internalization of virus.
DOMAININ THE HN GLYCOPROTEIN
OF NEWCASTLE
DISEASE
VIRUS
RONALD 11. IORIO, JODY B. BORGMAN, RHONA L. GLICKMAN AND MICHAEL A. BRATT, Molecular Genetics and Microbiology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01605, U.S.A. a panel of monoclonal Previously, antibodies (MAbs) delineated four antigenic sites on the hemagglutinin-neuraminidase (HN) glycoprotein of the strain of Australia-Victoria Newcastle disease virus. Infectivity neutralization of several virulent and avirulent strains of NDV by this panel of Mabs was measured: epitopes in three sites were highly conserved, but the epitope recognized by the lone MAb to site 3 was not (Virus Res. 1: 5131, 1984). An additional panel of MAbs is now described, three of which bind to epitopes within antigenic site 3. Neutralization analysis of temperaturesensitive mutants and antigenic variants selected with these MAbs have established that these MAbs each bind to different epitopes in site 3. All four site 3 epitopes were found to be divergent in the heterologous strains, while additional new antibodies confirm the high degree of conservation of epitopes outside site 3: thus, among site 3 epitopes, 4/4 are divergent in the heterologous strains, while 8/8 epitopes in sites other than 3 are highly conserved. This strongly suggests that the strain-specificity originally attributed to a single epitope in site 3 is a property of a more expansive domain of the HN molecule. The potential importance of this variation in site 3 will be related to our previous demonstration of a requirement for antibody to all four antigenic sites for neutralization comparable to that obtained with polyvalent sera (3. Virol. 51:445, 1984).
59
116
OF INFLUENZA VIRUS BY MONOMERIC AND
HOWARD P. TAYLOR and NIGEL J. DIMMOCK, Department University of Warwick, Coventry CV4 ‘7AL, England.
of Biological
115a
Sciences,
The mechanism of neutralization of influenza virus (Fowl plague virus/Restock/34 H7Nl) depended on the character of the neutralizing antibody. When neutralized by either IgG or monomeric IgA virus attached to and penetrated BHK-21 cells from 4OC to 25OC This indicated that at a rate indistinguishable from that of non-neutralized virus. neutralizing monomeric IgA and IgG must have exerted an effect at a stage later than penetration. In contrast both neutralizing Considering the attachment. and pentameric respectively) However, at 25°C and 37OC None of this attached virus and sIgA interfered with the
A STRAIN-SPECIFIC
secretory IgA (sIgA) and IgM at 4OC completely blocked large molecular structures of these antibodies (dimeric neutralization is probably mediated by steric hindrance. neutralizing sIgA and IgM inhibited attachment by 50%. was internalized. Therefore at these temperatures IgM endocytic event responsible for internalization of virus.
DOMAININ THE HN GLYCOPROTEIN
OF NEWCASTLE
DISEASE
VIRUS
RONALD 11. IORIO, JODY B. BORGMAN, RHONA L. GLICKMAN AND MICHAEL A. BRATT, Molecular Genetics and Microbiology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01605, U.S.A. a panel of monoclonal Previously, antibodies (MAbs) delineated four antigenic sites on the hemagglutinin-neuraminidase (HN) glycoprotein of the strain of Australia-Victoria Newcastle disease virus. Infectivity neutralization of several virulent and avirulent strains of NDV by this panel of Mabs was measured: epitopes in three sites were highly conserved, but the epitope recognized by the lone MAb to site 3 was not (Virus Res. 1: 5131, 1984). An additional panel of MAbs is now described, three of which bind to epitopes within antigenic site 3. Neutralization analysis of temperaturesensitive mutants and antigenic variants selected with these MAbs have established that these MAbs each bind to different epitopes in site 3. All four site 3 epitopes were found to be divergent in the heterologous strains, while additional new antibodies confirm the high degree of conservation of epitopes outside site 3: thus, among site 3 epitopes, 4/4 are divergent in the heterologous strains, while 8/8 epitopes in sites other than 3 are highly conserved. This strongly suggests that the strain-specificity originally attributed to a single epitope in site 3 is a property of a more expansive domain of the HN molecule. The potential importance of this variation in site 3 will be related to our previous demonstration of a requirement for antibody to all four antigenic sites for neutralization comparable to that obtained with polyvalent sera (3. Virol. 51:445, 1984).
59
116