STUDY OF THE PROTECTIVE IMMUNITY OF COEXPRESSED GLYCOPROTEIN-H AND GLYCOPROTEIN-L OF EQUINE HERPESVIRUS-1 IN A MURINE INTRANASAL INFECTION MODEL

Equine herpesvirus-1 (EHV-1) glycoproteins H, and L (gH and gL) expres sed individually or co-expressed by recombinant baculoviruses were use d to immunise BALB/c mice prior to intranasal challenge in a murine mo del of respiratory infection. Only the co-expressed material (EHV-1 gH /gL) induced neutralising antibody (low levels). The same immunogen al so produced the strongest cellular responses. Immunisation with gH/gL and, to a lesser extent, with gH alone was associated with a reduction of virus load in nasal turbinates and olfactory bulbs after challenge infection. Viraemia, detected by polymerase chain reaction, was also reduced. No such protective effects were observed for gL alone. Adopti ve transfer of lymphocytes from gH/gL-immunised mice to naive mice sub sequently challenged with EHV-1 indicated that both CD4(+) and CD8(+) cells had a role in protective immunity. Although clearance of EHV-1 f rom respiratory tissue was not as effective as previously found for gl ycoproteins D or C, these experiments provide evidence that the co-exp ression of EHV-1 gL with gH generates a conformational neutralising ep itope which is not present in either molecule alone, and suggests that gH/gL antigen may have a better potential as a component of an EHV-1 vaccine than gH alone. (C) 1998 Elsevier Science B.V.