Overlapping fragments of the envelope protein of feline immunodeficiency virus (FIV) have been expressed in Escherichia coli. Screening of 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.
Immune responses to the infectious bronchitis virus (IBV) nucleocapsid protein were studied using a recombinant-DNA expression product. In mice, a lymphocyte proliferative response and a delayed-type hypersensitivity reaction to IBV were induced upon immunization with this nucleocapsid protein. Next, we studied the role of the expressed nucleocapsid protein in induction of a protective immune response to IBV in chickens. Chickens were primed with nucleocapsid protein and subsequently boosted with inactivated IBV, strain M41. Proliferative responses of blood mononuclear cells corresponded with increased mean haemagglutination inhibition and virus neutralization titres. Finally, an increased tracheal protection against challenge with live IBV was observed. These results indicate that infectious bronchitis virus nucleocapsid protein is a relevant target for immune recognition in both the mouse and the chicken.
A monoclonal antibody, designated CLB-LFA-1/1, directed to the human lymphocyte-function-associated antigen 1 (LFA-1) was raised by immunization of mice with the peripheral blood lymphocytes of a T gamma lymphocytosis patient. The monoclonal antibody was selected by inhibition of the natural killer cell and the antibody-dependent killer cell activity of the patient's T gamma lymphocytes. In addition, the monoclonal antibody was shown to inhibit the cytotoxic activity of T cell clones specific for either class I or class II HLA molecules. The antigen recognized by CLB-LFA-1/1 consisted of three polypeptide chains with molecular weights of 180 000 (alpha), 155 000 and 94 000 (beta). The antibody reacted with T cells, B cells, monocytes and granulocytes, and stained normal T gamma cells and T gamma cells of patients with T gamma lymphocytosis two- to threefold stronger than normal T cells. It was shown that LFA-1 and the Fc receptor on T gamma cells did not comodulate and it is therefore concluded that Fc receptors and LFA-1 are independent membrane structures, both required for the killer cell activity of T gamma cells.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.