Characterization of monoclonal antibodies against the G1 and N proteins of LaCrosse and Tahyna, two California serogroup bunyaviruses

Abstract

Antibody-secreting hybrid cell lines were isolated by fusion of spleen cells from BALB/c mice infected with LaCrosse and Tahyna viruses with mouse myeloma cells. Of 23 cell lines, 15 secreted immunoglobulins which precipitated the G1 envelope glycoprotein, and 8 secreted immunoglobulins which precipitated the nucleocapsid protein; none reacted with the two other virion proteins, G2 or L. Monoclonal antibodies were characterized in neutralization (N), hemagglutination inhibition (HI), and ELISA tests against 11 California serogroup viruses. (i) Antibodies against the G1 viral glycoprotein fell into four groups designated A, B, C, and D. Groups A and B antibodies had high N and HI titers; group A antibodies were virus specific while those in group B were cross-reactive with many California serogroup viruses. Groups C and D antibodies had no N or HI activity, with one exception which did not neutralize but had HI activity. Group C antibodies bound preferentially to the homologous virus, while group D antibodies were cross-reactive. The concordance of N and HI responses suggests that the viral glycoprotein has a single domain which binds to cellular receptors and that groups A and B monoclonal antibodies interfere with this function. (ii) Nucleocapsid antibodies showed neither N nor HI activity and fell into two groups, designated E and F; group E antibodies bound preferentially to the homologous virus, while group F antibodies were cross-reactive with other California serogroup viruses. (iii) Monoclonal antibodies can be used to rapidly determine the phenotype of reassortants between LaCrosse and Tahyna viruses, for two of three gene segments. (iv) The identification of specific shared and unshared antigenic determinants provides a much improved rationale for the serologic taxonomy of California viruses, and suggests possible revisions in existing classification. Use of selected monoclonal antibodies also markedly facilitates identification of virus isolates.