Antibody responses, cytokine levels and protection of mice immunised with HSV-2 antigens formulated into NISV or ISCOM delivery systems S.A. Mohamedi a , J.M. Brewer b , J. Alexander b , A.W. Heath a , R. Jennings a, * a Sheeld Institute for Vaccine Studies, Division of Molecular and Genetic Medicine, Floor `F', University of Sheeld Medical School, Beech Hill Road, Sheeld S10 2RX, UK b Department of Immunology, University of Strathclyde, The Todd Centre, 31 Taylor Street, Glasgow G4 0NR, UK Received 7 July 1999; received in revised form 10 November 1999; accepted 7 December 1999 Abstract The immunogenicity of a type 2 herpes simplex virus (HSV-2) antigen preparation following its formulation into immunostimulating complexes (ISCOMs) or non-ionic surfactant vesicles (NISV) was investigated in a murine model. The immune responses induced by each formulation were characterised by antigen speci®c total and subclass serum responses, and by lymphocyte proliferation and cytokine (interleukin-2 (IL-2), interleukin-4 (IL-4) and interferon-gamma (IFN-g)) production by in vitro restimulated spleen cells. The degree of protection aorded to mice by these various HSV-2 vaccine preparations against homologous (HSV-2) and heterologous (HSV-1) challenge infection was also determined. The ®ndings suggest that formulation of the HSV-2 glycoprotein antigens with ISCOM or NISV delivery vehicles, and the methods used to prepare these formulations, in¯uenced the immunogenicity of the ®nal preparation. Higher IgG2a and neutralising antibody levels, IL-2 and IFN-g levels and lymphoproliferative responses were noted in mice immunised with the HSV-2 ISCOM formulated vaccine preparation. Furthermore, although HSV-2 antigens formulated in dehydration±rehydration NISV, or entrapped in NISV by freeze±thawing at 308C (HSV-2 NISV 30), also elicited relatively high antibody, IL-2 and IFN-g levels and relatively high lymphoproliferative responses, formulation of HSV-2 antigens by freeze±thawing with NISV at 608C (HSV-2 NISV 60) did not. There were no dierences between any of the HSV-2 vaccine formulations in terms of IL-4 induction in in vitro stimulated spleen cell cultures. Almost complete protection against HSV-2 challenge was aorded by the HSV-2 ISCOM preparation, while partial protection against challenge infection was aorded by the HSV-2 NISV 30 vaccine formulation. The ®ndings are discussed in relation to the nature of the immune mechanisms, particularly Th1- or Th2-like responses, that may be elicited by HSV-2 antigen preparations formulated into various delivery systems and the relevance of these immune responses to protection against HSV infection in the murine model. 7 2000 Elsevier Science Ltd. All rights reserved. Keywords: HSV-2 vaccine; Immunostimulating complexes (ISCOMs); Non-ionic surfactant vesicles (NISV) 1. Introduction Infections with herpes simplex virus type 2 (HSV-2) are a major public health problem and continue to be so partly because of the high proportion of sub-clinical or unrecognised cases and the frequency of viral shed- ding in the absence of symptoms [1,2]. Although neo- natal herpes infections are relatively rare, they can give rise to serious systemic disease [3]. HSV-2 is also a common cause of encephalitis in the United States aecting both children and adults [4]. The mortality rate of neonatal HSV infection has declined with current antiviral therapy, although the mortality rate in CNS disease (15%) and disseminated Vaccine 18 (2000) 2083±2094 0264-410X/00/$ - see front matter 7 2000 Elsevier Science Ltd. All rights reserved. PII: S0264-410X(99)00567-8 www.elsevier.com/locate/vaccine * Corresponding author. Tel.: +44-114-272-4072; fax: +44-114- 273-9926. E-mail address: r.jennings@shef.ac.uk (R. Jennings).