An adherent cell lyses virus-infected targets: characterization, activation, and fine specificity of the cytotoxic cell.

We have previously reported that mice with defective T lymphocyte function clear a primary reovirus type 1 infection in a normal fashion. The present studies were initiated to determine what cells may play a role in the clearance of this primary infection. We show that macrophages from unprimed mice are capable of lysing reovirus type 1-infected target cells in the absence of specific antibody. Macrophages from nu/nu mice have higher levels of this lytic activity than macrophages from nu/+ and normal mice. In addition, PEC from endotoxin nonresponsive C3H/HeJ mice have virtually no anti-viral lytic activity, while PEC from C3H/FeJ mice have high levels of such activity. Incubation of PEC from C3H/HeJ mice overnight in Con A supernatants restores this lytic activity. PEC are capable of lysing reovirus type 1-infected target cells but not those infected with type 3 reovirus. Using intertypic recombinant viruses, we show this striking target cell specificity to be a property of the sigma 1 protein, the viral hemagglutinin.