To further understand the effects of opiates on the pathogenesis of infectious disease, naturally occurring pathogens were studied in a swine model. Swine were given morphine for 21-42 days to establish a tolerant, dependent state. On day 7 after morphine initiation, pigs were challenged with swine herpesvirus-1 (SHV-1); on day 14, selected animals were superinfected with Pasteurella multocida. Evaluations were made ofthe clinical disease, protective effect ofSHY-1 vaccination, and pathology. Morphine-dependent animals developed significantly greater virus-induced and secondary bacterial pneumonia. Prior vaccination with SHY-1 was not protective against pneumonia in morphine-dependent pigs. Unexpectedly, clinical signs associated with neurologic disease were less pronounced, and mortality from viral encephalitis was decreased in morphinetreated animals. Collectively, the findings demonstrate that morphine dependence is associated with a marked alteration of the pathogenesis of SHY-1 and that the effects of this opiate on pathogenesis are determined by the specific site of infection.
Bibliographical noteFunding Information:
Received I I September 1992; revised 8 February 1993. Presented in part: Second International Symposium on Drugs of Abuse, Immunity, and AIDS, Clearwater, Florida, 1-3 June 1992. This work was conducted in accordance with the animal care and use policy of the University of Minnesota and the Public Health Service Policy on Humane Care and Use of Laboratory Animals. Financial support: National Institute of Drug Abuse (contract 271-89-8155). Reprints or correspondence: Dr. Thomas W. Molitor, Dept. of Clinical and Population Sciences, College of Veterinary Medicine, University of Minnesota, 1365 Gortner Ave., St. Paul, MN 55108.