However , during infection by EBV , ligation of CD2 caused thymocytes to proliferate in the absence of exogenous cytokines .
however , during infection by ebv , ligation of cd2 caused thymocytes to proliferate in the absence of exogenous cytokines .
O O O O O B-virus O O O B-protein_molecule O B-cell_type O O O O O O B-protein_family_or_group I-protein_family_or_group O