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Updated: Mar 27, 2026
Diagnosis of Ecto- and Endoparasites in Laboratory Rats and Mice
Published on: September 6, 2011
Detection of Chlamydia infection in Peromyscus species rodents from sylvatic and laboratory sources
Kyle H Ramsey1, Ira M Sigar2, Justin H Schripsema2
1Microbiology and Immunology Department, Midwestern University, Downers Grove, Illinois, 60515, USA kramse@midwestern.edu.
Abstract:
To determine if Chlamydia muridarum, or other chlamydiae, are enzootic in rodents, we probed a serum bank of wild Peromyscus spp. mice for immunoglobulin G-antibody reactivity to ultraviolet light-inactivated C. muridarum elementary bodies (EBs) using an enzyme-linked immunoassay. Applying a cut-off for a positive reaction of OD(405) nm = 0.1 at a 1:20 dilution, we found titratable antibody reactivity in 190 of 247 specimens surveyed (77%, mean OD(405) = 0.33 ± 0.26, range = 0.11-1.81, median = 0.25). In addition, serum samples were obtained from a colony of specific pathogen-free Peromyscus spp. maintained at the University of South Carolina and six of 12 samples were reactive (50%, mean OD(405) = 0.19 +/- 0.08, range = 0.1-0.32, median = 0.18). Lastly, 40 additional wild Peromyscus spp. were captured in a disparate region of Midwestern USA and 22 serum specimens were reactive (55%, mean OD(405) = 0.22 +/- 0.11, range = 0.1-0.48, median = 0.2). Specificity of selected reactive sera for chlamydial antigen was confirmed on Western blot using resolved purified EBs as the detecting antigen. From tissues removed from several mice at necropsy, the gene for chlamydial 16S ribosomal ribonucleic acid (rRNA) was amplified by polymerase chain reaction (PCR). Positive samples of 16S rRNA were subjected to additional PCR for the major outer membrane protein gene (ompA). The amplicons of three select ompA positive samples were sequenced with ≥99% homology with C. muridarum. Our findings indicate that chlamydial infection is enzootic for Peromyscus spp., and that C. muridarum, or a closely related species or strain, is likely the agent in the tested rodent species.
Insights
Chlamydia muridarum, a bacterium, is endemic in wild Peromyscus mice. Researchers detected antibodies and DNA, confirming Chlamydia infection in these rodents, suggesting it
Area of Science:
- Veterinary Microbiology
- Zoonotic Diseases
- Rodent Ecology
Background:
- Chlamydial infections are significant in various animal populations.
- The enzootic status of chlamydiae in wild rodent populations, particularly Peromyscus spp., remains largely uncharacterized.
- Understanding Chlamydia muridarum prevalence in rodents is crucial for assessing potential transmission dynamics and ecological impact.
Purpose of the Study:
- To investigate the presence and prevalence of Chlamydia muridarum or related chlamydiae in wild Peromyscus spp. mice.
- To determine if chlamydial infections are enzootic in Peromyscus populations.
- To identify the specific Chlamydia species or strain circulating in these rodents.
Main Methods:
- Enzyme-linked immunosorbent assay (ELISA) was used to detect immunoglobulin G (IgG) antibodies against C. muridarum elementary bodies (EBs) in Peromyscus spp. serum samples.
- Western blot analysis confirmed the specificity of reactive sera against chlamydial antigens.
- Polymerase chain reaction (PCR) was employed to amplify chlamydial 16S ribosomal RNA (rRNA) and major outer membrane protein (ompA) genes from rodent tissues. Sequencing of ompA amplicons was performed for species identification.
Main Results:
- Antibody reactivity to C. muridarum EBs was detected in a significant proportion of wild Peromyscus spp. sera (77%) and in specific pathogen-free colonies (50%) and wild-caught mice from a different region (55%).
- Western blot confirmed the specificity of the antibody responses.
- PCR amplification and sequencing of the ompA gene from three samples revealed ≥99% homology with Chlamydia muridarum, indicating infection with this agent or a closely related strain.
Conclusions:
- Chlamydial infections are enzootic in Peromyscus spp. rodent populations.
- Chlamydia muridarum, or a closely related species/strain, is likely the causative agent responsible for these infections in the studied Peromyscus populations.
- These findings highlight the importance of Peromyscus spp. as potential reservoirs for chlamydial agents.
