Journal of NeuroVirology, 10: 409–413, 2004 c  2004 Journal of NeuroVirology ISSN: 1355-0284 print / 1538-2443 online DOI: 10.1080/13550280490523643 Short Communication Neuronal apoptosis in immunodeficient mice infected with the challenge virus standard strain of rabies virus by intracerebral inoculation Maegan Rutherford 1 and Alan C Jackson 1,2 Departments of 1 Microbiology and Immunology and 2 Medicine, Queen’s University, Kingston, Ontario, Canada The challenge virus standard-11 strain (CVS) of fixed rabies virus produces neuronal apoptosis in widespread areas of the brain of mice after intracerebral inoculation. The role of the adaptive immune response in producing neuronal apoptosis in this model was evaluated by comparing the infections in adult C57BL/6J mice with nude mice (T cell deficient) and Rag1 mice (T and B cell deficient). Both strains of immunodeficient mice showed very similar clinical disease and neuropathological findings, including marked neuronal apopto- sis. The adaptive immune response is unlikely of fundamental importance in producing neuronal apoptosis in the brains of mice in this model. Journal of NeuroVirology (2004) 10, 409–413. Keywords: neuronal apoptosis; rabies; viral pathogenesis An understanding of rabies pathogenesis will likely be important in the development of novel therapies for rabies encephalitis, which is a fatal disease in hu- mans (Jackson, 2002a, 2002b; Jackson et al, 2003). Neurotropic viruses may cause neuronal cell death by either apoptosis or necrosis (Griffin and Hardwick, 1999; Allsopp and Fazakerley, 2000; Fazakerley and Allsopp, 2001). Apoptosis depends on synthesis of macromolecules and requires energy, whereas, in contrast, necrosis is associated with energy failure (Friedlander, 2003). The destruction of infected cells by apoptosis has been proposed as an innate host cellular response that acts to limit viral propagation during infection (Alcami and Koszinowski, 2000). The challenge virus standard-11 strain (CVS) of fixed rabies virus has been observed to induce apop- Address correspondence to Dr. Alan C. Jackson, Kingston Gen- eral Hospital, Connell 725, 76 Stuart Street, Kingston, ON K7L 2V7, Canada. E-mail: jacksona@post.queensu.ca The authors are grateful for technical assistance from Pamini Rasalingam, statistical advice from Dr. Miu Lam (Department of Community Health and Epidemiology, Queen’s University), and for the gift of monoclonal antibody 5DF12 from Dr. Alexander I. Wandeler (Centre for Rabies Expertise, Canadian Food Inspection Agency, Nepean, Ontario). This work was supported by Canadian Institutes of Health Research grant MOP-64376 and the Queen’s University Violet E. Powell Research Fund (both to A.C. Jackson). Received 22 April 2004; revised 14 June 2004; accepted 6 August 2004. totic cell death in rat prostatic adenocarcinoma cells (Jackson and Rossiter, 1997), mouse neuroblastoma cells (Theerasurakarn and Ubol, 1998), and in mouse embryonic hippocampal neurons (Morimoto et al, 1999), although only limited apoptosis is produced in human neuroblastoma SK-N-SH and lymphoblas- toid Jurket T-cell lines (Thoulouze et al, 1997, 2003; Prehaud et al, 2003). CVS and other lyssaviruses have been shown to induce caspase dependent apopto- sis in mouse neuroblastoma cells (Ubol et al, 1998; Kassis et al, 2004). Rabies encephalitis in adult, suck- ling, and neonatal mice inoculated intracerebrally with CVS is associated with marked neuronal apop- tosis in multiple brain regions (Jackson and Rossiter, 1997; Jackson and Park, 1998; Theerasurakarn and Ubol, 1998). In contrast, adult animals infected with CVS by peripheral routes of inoculation demonstrate severe and fatal encephalitis without prominent neu- ronal apoptosis (Reid and Jackson, 2001; Jackson, 2003), and CD3-positive T cells are the main con- tributor to the pool of apoptotic cells in central ner- vous system (CNS) tissues (Baloul and Lafon, 2003). Morimoto et al (1999) have observed that CVS vari- ants that are more neurovirulent in adult mice pro- duce less apoptosis in vitro over a period of 72 h in primary hippocampal neurons than produced by less neurovirulent variants. Lafon and coworkers have shown that intramuscular inoculation in the hindlimbs of mice with the Pasteur strain of rabies