IgG Neutralization of Type A Influenza Viruses and the Inhibition of the Endosomal Fusion Stage of the Infectious Pathway in BHK Cells

Monoclonal Antibodies against the Fusion Peptide of Hemagglutinin Protect Mice from Lethal Influenza A Virus H5N1 Infection

“…MAb 1C9 recognizes the epitope GLFGAIAGF and hence targets and binds to the fusion peptide of HA. Due to this, it could block the pH-dependent conformational change and/or the requisite interactions between the viral and endosomal membrane proteins, which would delay or prevent the penetration of the viral core into the target cell cytoplasm (14,21). As a result, it could prevent further replication of the virus and hence mediate more protection against influenza A virus infection.…”

Two neutralizing anti-V3 monoclonal antibodies act by affecting different functions of human immunodeficiency virus type 1

“…These also did not inhibit the attachment of neutralized radiolabelled virus to a variety of different cells including ciliated tracheal cells, did not inhibit its internalization (Armstrong & Dimmock, 1992;reviewed by Dimmock, 1993) or the endocytosis/fusion of neutralized virions by BHK cells as measured by fluorescence dequenching (Outlaw & Dimmock, 1993). Here therefore are two enveloped virions, studied using different techniques, that are neutralized by a mechanism that requires antibody attached to the distal part of an envelope protein to affect the function of an internal virion component.…”

“…Neutralization of a virus (reviewed by Dimmock, 1993Dimmock, , 1995 is defined as the loss of infectivity that results from antibody binding to epitopes on the surface of a virus particle. This also has a quantitative dimension that is probably specific for each MAb-virus combination.…”

“…The commonly regarded mechanism of neutralization by steric inhibition of contact between the viral attachment site and its cell receptor occurs only rarely, and a direct quantitative relationship has been established only for a few virus-IgG MAb combinations [e.g. certain MAbs to Newcastle disease virus (Iorio et aI., 1989); rhinovirus 14 and MAb 17-1A (Smith eta]., 1993); see Table 1 of Dimmock, 1993]. Dimmock (1993,1995) has discussed the many mechanisms of neutralization which occur.…”

High and low efficiency neutralization epitopes on the haemagglutinin of type A influenza virus.

“…However, as a generalization it appears that, at relatively low levels of neutralization, infectivity is reduced by aggregation of virions, some inhibition of attachment of neutralized virus to the target cell, and some inhibition of fusion of viral and cell membranes. None of these alone is sufficient to account for the loss of infectivity observed, but if added together could account for much of the neutralization (Outlaw et al, 1990 ;Outlaw & Dimmock, 1993). It is difficult to know if such a calculation is justified.…”