Submitted to: Zoonoses and Public Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 1, 2007
Publication Date: October 1, 2007
Citation: Olsen, S.C., Waters, W.R., Stoffregen, W.C. 2007. An Aerosolized Brucella spp. Challenge Model for Laboratory Animals. Zoonoses and Public Health. 54(8):281-285. Interpretive Summary: One concern is that, brucellosis, a disease characterized by abortion and fetal losses, may be used as a biological weapon through aerosol delivery. In addition, the persistence of B. abortus, B. melitensis, and B. suis infections in domestic livestock or wildlife pose a significant health risk for transmission to humans. One known route for human infection is through aerosolization. Infection of humans with Brucella causes a wide range of moderate to severe clinical symptoms including the classical syndrome of "undulant fever". In the current study we characterize an aerosol model of delivering a Brucella challenge in a murine model of brucellosis and compare it to the traditional challenge model. Our data suggests that in a murine model, vaccines which induce protection in the traditional challenge model do not provide protection against an aerosol challenge. This data may suggest that current models are insufficient for characterizing responses to infections resulting from aerosolized Brucella.
Technical Abstract: To characterize the optimal aerosol dosage of Brucella abortus strain 2308 (S2308) and B. melitensis (S16M) in a laboratory animal model of brucellosis, dosages of 10**3 to 10**10 CFU were nebulized to mice. Although tissue weights were minimally influenced, total colony-forming units (CFU) per tissue increased beginning at 10**6 or 10**7 CFU dosages, with 109 CFU appearing to be an optimal dosage for S16M or S2308 aerosol delivery. At 12 weeks after vaccination with 10**7 CFU of B. abortus strain RB51 (SRB51) or saline (control), mice were challenged intraperitoneally (6.4 x 10**4 CFU) or via aerosol (1.76 x 10**9 CFU) with S2308. Mice vaccinated with SRB51 had reduced (P<0.05) splenic, liver, and lung colonization (Total CFU and CFU/gm) after intraperitoneal challenge with S2308 as compared to control mice after intraperitoneal S2308 challenge. Control and SRB51-vaccinated mice did not differ (P>0.05) in splenic, liver, or lung colonization after aerosol S2308 challenge. Failure to demonstrate vaccine protection was not due to a high aerosol challenge dosage as colonization of spleen and liver tissues was lower (P<0.05) after aerosol challenge when compared to control mice after intraperitoneal S2308 challenge.