Guinea pig abscess/hypersensitivity model for study of adverse vaccination reactions induced by use of Q fever vaccines

By Wilhelmsen, C.L. - Waag, D.M.

Background and Purpose: The Coxiella burnetii phase-I cellular vaccine is efficacious in humans, imparting nearly complete protection against Q fever. However, this vaccine can also induce sterile abscesses and granulomas at the inoculation site in humans previously sensitized by natural infection or vaccination. To decrease the possibility of vaccinating immune persons, vaccinees are currently screened by skin testing to detect pre-existing Q fever immunity. We developed a model of abscess hypersensitivity in Hartley guinea pigs to assess the likelihood that Q fever vaccines would induce adverse vaccination reactions in previously sensitized individuals. Methods: Guinea pigs (4 to 6/group) were sensitized to C. burnetii by immunization and aerosol challenge, or by intraperitoneal inoculation. Eight weeks later, animals were then vaccinated SC with a Q fever cellular (WCI) or chloroform:methanol residue (CMR) vaccine. Development of adverse reactions at the vaccination site was assessed histologically and by observation of increases in erythema and/or induration. Results: The WCI vaccine caused greater magnitude and duration of erythema and induration at the vaccination sites than did the CMR vaccine. In addition, non-immune guinea pigs developed induration when given WCI, but not CMR vaccine. Conclusions: The CMR vaccine may prove a safe alternative to WCI vaccines for use in individuals unscreened for prior immunity to C. burnetii.