ANTIBODY-RESPONSE IN CATS TO THE ENVELOPE PROTEINS OF FELINE IMMUNODEFICIENCY VIRUS - IDENTIFICATION OF AN IMMUNODOMINANT NEUTRALIZATION DOMAIN

Overlapping fragments of the envelope protein of feline immunodeficiency virus (FIV) have been expressed in Escherichia coli. Screening of a cat sera for antibodies to these fragments revealed that the immunodominant domain of the FIV envelope is localized within the transmembrane protein (amino acids 687-741) and that both the variable region 3 (SU3, aa 385-417) and the COOH- terminus (aa 599-611) of the surface protein (SU) are highly immunogenic. Of all rabbit sera raised to the envelope protein fragments only the serum directed to SU3 was neutralizing. Both FIV-infected and SU3-immunized cats elicited neutralizing antibodies to SU3. Neutralizing antibodies in sera of infected cats could be absorbed by SU3, showing that SU3 is a major neutralization domain of FIV. © 1994 Academic Press, Inc.