Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2020 Feb 5:148:e21.
doi: 10.1017/S0950268820000059.

Transmission of Coxiella burnetii by ingestion in mice

H K Miller  1 , R A Priestley  1 , G J Kersh  1
Affiliations

Transmission of Coxiella burnetii by ingestion in mice

H K Miller et al. Epidemiol Infect. .

Abstract

Coxiella burnetii, the causative agent of Q fever, is widely present in dairy products around the world. It has been isolated from unpasteurised milk and cheese and can survive for extended periods of time under typical storage conditions for these products. Although consumption of contaminated dairy products has been suggested as a potential route for transmission, it remains controversial. Given the high prevalence of C. burnetii in dairy products, we sought to examine the feasibility of transmitting the major sequence types (ST16, ST8 and ST20) of C. burnetii circulating in the United States. We delivered three strains of C. burnetii, comprising each sequence type, directly into the stomachs of immunocompetent BALB/c mice via oral gavage (OG) and assessed them for clinical symptoms, serological response and bacterial dissemination. We found that mice receiving C. burnetii by OG had notable splenomegaly only after infection with ST16. A robust immune response and persistence in the stomach and mesenteric lymph nodes were observed in mice receiving ST16 and ST20 by OG, and dissemination of C. burnetii to peripheral tissues was observed in all OG infected mice. These findings support the oral route as a mode of transmission for C. burnetii.

Keywords: Alimentary tract; Coxiellae; Q fever; virulence; zoonoses.

PubMed Disclaimer

Conflict of interest statement

No competing financial interests exist.

Figures

Fig. 1.
Fig. 1.
Body weight and splenomegaly following oral infection with C. burnetii in immunocompetent BALB/c mice. Mice were infected with 106 of either NM (•), CM-SC1 (■) or GP-CO1 (▲) via (a) OG or (b) IP. Sterile PBS (○) was delivered via OG as negative controls. Data are presented as the mean percentage change in weight relative to day 0 ± S.E.M. (c) Spleen-to-body weight (mean ± S.E.M.) is shown for mice infected with NM (black), CM-SC1 (dark grey), GP-CO1 (light grey) or PBS (white) via OG or IP. *P < 0.05, **P < 0.01, ***P < 0.001 and ****P < 0.0001 as determined by Student's t-test relative to PBS OG negative controls.
Fig. 2.
Fig. 2.
Serological response following oral infection with C. burnetii in immunocompetent BALB/c mice. Serum was analysed for the presence of IgG antibodies against phase I (dashed line) and phase II (solid line) C. burnetii by indirect IFA. The GMT ± range is shown for mice receiving either NM (•), CM-SC1 (■) or GP-CO1 (▲) via (a) OG or (b) IP. Mice receiving PBS were seronegative at every time point (data not shown). Values below the limit of detection are indicated as <16.
Fig. 3.
Fig. 3.
Dissemination following oral infection with C. burnetii in immunocompetent BALB/c mice. (a) Blood, (b) spleens, (c) livers and (d) lungs were analysed for the presence of C. burnetii DNA by quantitative PCR. Cycle threshold (Ct) data for the C. burnetii com1 gene were normalised to murine Actb (Applied Biosystems, Waltham, MA) and normalised cycle threshold values (ΔCt) were transformed using 2−ΔCt/10−6 [35], and reported as arbitrary quantity units. Individual data points and the mean (bar) are shown for mice receiving either NM (•), CM-SC1 (■) or GP-CO1 (▲) via OG or IP. Open symbols represent values below the limit of detection. No C. burnetii DNA was detected in any PBS control mice (data not shown).
Fig. 4.
Fig. 4.
Colonisation of the gastrointestinal tract following oral infection with C. burnetii in immunocompetent BALB/c mice. (a) Mesenteric lymph nodes (MLN), (b) small Intestines, (c) caecum, (d) colon and (e) stomach were analysed for the presence of C. burnetii DNA by quantitative PCR. Cycle threshold (Ct) data for the C. burnetii com1 gene were normalised to murine Actb (Applied Biosystems, Waltham, MA) and normalised cycle threshold values (ΔCt) were transformed using 2−ΔCt/10−6 [35], and reported as arbitrary quantity units. Individual data points and the mean (bar) are shown for mice receiving either NM (•), CM-SC1 (■) or GP-CO1 (▲) via OG. Open symbols represent values below the limit of detection. No C. burnetii DNA was detected in any PBS control mice (data not shown).
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Eldin C et al. (2013) Coxiella burnetii DNA, but not viable bacteria, in dairy products in France. The American Journal of Tropical Medicine and Hygiene 88, 765–769. - PMC - PubMed
    1. Galiero A et al. (2016) Occurrence of Coxiella burnetii in goat and ewe unpasteurized cheeses: screening and genotyping. The International Journal of Food Microbiology 237, 47–54. - PubMed
    1. Abdali F et al. (2018) Prevalence of Coxiella burnetii in unpasteurized dairy products using nested PCR assay. The Iranian Journal of Microbiology 10, 220–226. - PMC - PubMed
    1. Pearson T et al. (2014) High prevalence and two dominant host-specific genotypes of Coxiella burnetii in U. S. milk. BMC Microbiology 14, 41. - PMC - PubMed
    1. Barandika JF et al. (2019) Viable Coxiella burnetii in hard cheeses made with unpasteurized milk. The International Journal of Food Microbiology 303, 42–45. - PubMed