Comparative Medicine Volume 74: Issue 6

Chlamydia muridarum (Cm) has reemerged as a moderately prevalent infectious agent in research mouse colonies. Despite its experimental use, few studies evaluate Cm’s effects on immunocompetent mice following its natural route of infection. A Cm field isolate was administered (orogastric gavage) to 8-wk-old female BALB/cJ (C) mice. After shedding was confirmed (through 95 d), these mice were cohoused with naïve C57BL/6J (B6), C, and Swiss (J:ARC[S]) mice (n = 28/strain) for 30 d. Cohoused mice (n = 3 to 6 exposed and 1 to 6 control/strain) were evaluated 7, 14, 21, 63, 120, and 180 d post-cohousing (DPC) via hemograms, serum biochemistry analysis, fecal quantitative PCR, histopathology, and Cm major outer membrane protein immunohistochemistry. Immunophenotyping was performed on spleen (B6, C, and S; n = 6/strain) and intestines (B6; n = 6) at 14 and 63 DPC. Serum cytokine concentrations were measured (B6; n = 6 exposed and 2 control) at 14 and 63 DPC. All B6 mice were shedding Cm by 3 through 180 DPI. One of 3 C and 1 of 6 S mice began shedding Cm at 3 and 14 DPC, respectively, with the remaining shedding thereafter. Clinical pathology was nonremarkable. Minimal-to-moderate enterotyphlocolitis and gastrointestinal-associated lymphoid tissue (GALT) hyperplasia were observed in 15 and 47 of 76 Cm-infected mice, respectively. Cm antigen was frequently detected in GALT-associated surface intestinal epithelial cells. Splenic immunophenotyping revealed increased monocytes and shifts in T-cell population subsets in all strains/time points. Gastrointestinal immunophenotyping (B6) revealed sustained increases in total inflammatory cells and elevated cytokine expression in innate lymphoid and effector T cells (large intestine). Elevated concentrations of proinflammatory cytokines were detected in the serum (B6). Results demonstrate that while clinical disease was not appreciated, 3 commonly used strains of mice are susceptible to chronic enteric Cm infection which may alter various immune responses. Considering the widespread use of mice to model gastrointestinal disease, institutions should consider excluding Cm from their colonies.

The congenic BALB/c-crup (‘crup’ meaning ‘cruza-pernas’ in Portuguese or cross legs in English), a homozygous recessive mutant mouse derived from N-ethyl-N-nitrosourea mutagenesis, exhibits a unique phenotype characterized by hindlimb crossing when the mouse is suspended by its tail, along with age-related neuromotor issues. The study aimed to identify the genetic mutation causing the BALB/c-crup phenotype and evaluate the behavioral responses of the mice. Open field test, elevated plus maze, and elevated beam experiments were conducted to evaluate general activity, motor function, as well as sensorimotor and autonomic nervous systems. Genetic mapping and exome analysis identified a nonsynonymous (missense mutation), a single nucleotide variant, in the Taf15 gene. This mutation results in the p.G55S substitution, where glycine is replaced by serine at position 55 in the gene product. Longitudinal assessment by the open field test revealed altered locomotion, decreased mobility, and reduced rearing and grooming frequency in mutant mice. Sensorimotor function declines were observed through reduced surface righting reflex scores, grip strength, and increased hindquarter angle. In the elevated beam test, mutants exhibited tail hypotonia and aversion to traversing the beam. The elevated plus maze revealed altered behavior in closed arms, suggesting increased anxiety-like behavior or sensorimotor impairment. Our findings provide insights into neurologic and behavioral anomalies associated with a Taf15 gene mutation. The altered locomotion, sensory impairments, and disorientation observed in the crup phenotype indicate a progressive neuromotor condition, potentially serving as a novel mouse model for neurodegenerative diseases.

This corrects the article DOI:

In the original article titled “Seasonal Variation of Laboratory Animals as a Consideration for Research Reproducibility,” published in Vol 73, Issue 4 (August 2023), pages 255 to 259, there are several errors in which “August” was substituted for “month.” Specifically, in the section “What Is Seasonal Variation,” the sentence “… rhythms having a period of greater than a single day are referred to as infradian if they occur over a period of about a August and circannual if the period approximates one year” should be “… rhythms having a period of greater than

Effect of Anesthesia on Hematologic Parameters of Female Domestic Swine (Sus scrofa domestica)

McKayla M CarlsonDVM,

Joseph D SciurbaDVM, DACLAM,

Kim E SaundersDVM, DACLAM,, and

Jennifer H KopankeDVM, PhD, DACLAM

Multicenter Analysis of the Attributable Diarrhea Risk and Odds Ratios of Pathogens in Rhesus Macaques (Macaca mulatta) Using Multiplex PCR Gastrointestinal Panel Testing and Conventional Fecal Culture

Andrew J HaertelDVM, DACLAM, MPH,

Samuel McCoyBS,

Colleen S McCoyMS, DVM, DACLAM,

Marcelo Delos ReyesBA, BS,

Heidi PalmerBS,

Paul-Michael SosaBS,

Madeline C BurkeDVM, MPH,

Massiel MelendezBS,

Peter B NhamMS,

Gregory TimmelDVM, DACLAM,

JoAnn YeeMLS,

Koen K A Van RompayDVM, PhD,

Jeffrey A RobertsDVM, DACLAM, and

L Drew MartinDVM, DACLAM

The Final Scene

AALAS Journal Updates for Authors

Chlamydia muridarum Causes Persistent Subclinical Infection and Elicits Innate and Adaptive Immune Responses in C57BL/6J, BALB/cJ, and J:ARC(S) Mice Following Exposure to Shedding Mice

Studies of C57BL/6J Mice Deficient in Receptors for IFNα/β and IFNγ as a Model for EV-D68 Acute Flaccid Myelitis

Postsurgical Carprofen Does Not Substantially Decrease Bacterial Growth in a Minipig Model of Staphylococcus aureus Deep Surgical Wound Infection

Exploring the Behavioral Traits of Male Mutant Crup Mice as an Experimental Neurodegenerative Disease Model

Erratum: Seasonal Variation of Laboratory Animals as a Consideration for Research Reproducibility

Erratum: AALAS Journals: Continual Adaptation to Meet Changing Environments

AALAS Members

How to access member-only articles.

Effect of Anesthesia on Hematologic Parameters of Female Domestic Swine (Sus scrofa domestica)

More Power for Less Money: Statistical, Power, and Cost Analyses That Account for Intracluster Correlation in Experiments with Same-Group Cage Mates

Multicenter Analysis of the Attributable Diarrhea Risk and Odds Ratios of Pathogens in Rhesus Macaques (Macaca mulatta) Using Multiplex PCR Gastrointestinal Panel Testing and Conventional Fecal Culture

Refining In-Cage Enrichment for Specialized Mouse Scenarios

Laboratory Animal Science Professional: July/August 2025