The present invention relates to isolated IgA antibodies, or fragments thereof, which have variable domains derived from an antibody that specifically binds to a CD4-induced (CD4i) epitope. In particular, the isolated IgA antibodies display enhanced neutralization activity relative to their IgG, non-chimeric counterparts. The invention also provides methods for therapy with the isolated IgA antibodies for the treatment of a subject having a viral infection or having an increased risk of a viral infection.
