Physico-chemical Analyses of the Humoral Immune Response to HIV-1: Quantification of Antibodies, Their Binding to Viral Antigens and

Antibodies against HIV-1 envelope glycoproteins (Env) as well as the Gag and other viral proteins are produced in the course of the HIV-1 infection. The isotypic composition differs between the antibody response to the Gag and the Env proteins. Falling plasma levels of antibodies directed to the Gag proteins are associated with progression of HIV-1-induced disease. Yet, it is antibodies directed to the Env protein that neutralize viral infectivity. How can we quantify these kinds of antibodies and predict their degree of complex formation with antigens in vivo and in vitro? How should we define, measure or calculate affinity, association and dissociation constants, on- and off-rate constants, and binding energy? What does the titer of a serum or plasma reveal about antibody affinity and concentration? How are antigenic peptides related to epitopes? What can antibody binding tell us about the tertiary and quaternary structure of HIV-1 proteins? How is viral neutralization best measured in relation to the binding of neutralizing antibodies? What can be the structural and functional basis of HIV-1 resistance to neutralization? These problems are discussed against the background of different derivations from the law of mass action