Experimental rabies in skunks: Immune response and salivary gland infection

Groups of striped skunks ( Mephitis mephitis) were inoculated intramuscularly with graded doses of street rabies virus. At various intervals after inoculation, saliva and sera were tested for rabies virus and neutralizing antibodies, respectively. Skunks that developed rabies were killed in terminal stages of the disease and the following examinations were made: titers of virus and antibody in submandibular salivary glands and brain, extent of immunofluorescence in submandibular salivary glands, and histologic examination of various tissues. Skunks that received inocula containing 4 × 10 4 to 4 × 10 5 mouse intracerebral lethal dose 50 (MICLD 50) had detectable serum neutralizing antibodies by 7–12 days postinoculation; however, most of the skunks that received lower doses (40 to 4 × 10 3 MICLD 50) did not have detectable serum neutralizing antibodies until clinical signs began. In the salivary glands, slight and extensive immunofluorescence corresponded to high and low titers of tissue neutralizing antibody. Also low viral titers were associated with high tissue neutralizing antibody titers. There was a close correlation between viral titers in right and left submandibular salivary glands. The results suggest that the immune response can impede the process of infection of the salivary glands resulting in lack of antigen or low amounts of antigen in this tissue. This could occur through interference with centrifugal neural transport of virus and/or neutralization of virus during transfer from neural elements to epithelial cells. Lack of infectious virus or low viral titers in salivary glands containing antigen and high levels of tissue neutralizing antibodies can be caused partly by postmortem virus neutralization (during viral titration). Des doses échellonnées de virus rabique des rues furent inoculées à des mouffettes striées ( Mephitis mephitis) par voie intramusculaire. La salive et le serum prelevés à des intervales pré-établies ont été échantillonnés pour la présence de virus et d'anticorps neutralisants respectivement. Les mouffettes succombant à la rage furent tuées en phase terminale et soumises aux examens suivants: le titrage de virus et d'anticorps dans les glandes sous-maxillaires et le cerveau, la répartion de l'immunofluorescence dans les glandes sous-maxillaires et l'examen histologique de différents tissus. Dans les mouffettes ayant recu des doses de virus contentant 4 × 10 4 à 4 × 10 5 doses léthales 50 souris (DL 50), les auteurs ont dé