Infectious agents have varying susceptibilities to thermal inactivation and/or mechanical removal from cages by the use of heated, pressurized water. In this study, we tested whether 5 specific infectious organisms (Candidatus savagella [segmented filamentous bacterium (SFB)], Helicobacter sp., mouse norovirus (MNV), Tritrichomonas sp., and Entamoeba muris) could survive the cage wash process and still infect naïve mice. These 5 organisms were chosen due to their prevalence in rodent colonies, environmental stability, and/or potential to influence experimental outcomes. Cages that had housed mice shedding all 5 organisms were assigned to 1 of 3 treatment groups: 1) sanitization in a tunnel washer followed by autoclaving (121 °C [250 °F] for 20 min; n = 40 cages); 2) sanitization in a tunnel washer (82 °C [180 °F] for an average of 30 s; n = 40 cages); or 3) control (bedding change only; n = 40 cages). The presence of these agents in the cage was assessed by performing PCR on swabs of the empty soiled cage interior before and after the treatment. In addition, to determine if any residual nucleic acid was infectious, 2 Swiss outbred (J:ARC(S)) female mice were housed for 7 d in cages from each treatment group. The above procedures were then repeated so that every week each pair of J:ARC(S) mice (n = 10 pairs of mice/treatment group) were housed in another cage that underwent the same treatment; this was done for a total of 4 consecutive, 1-wk-long periods. Swabs collected from soiled cages were PCR-positive for SFB, Helicobacter, MNV, Tritrichomonas, and Entamoeba in 99%, 97%, 39%, 63%, and 73% of the cages tested, respectively. Cages in the tunnel wash group that were PCR-positive for SFB, Helicobacter, Tritrichomonas, and Entamoeba before treatment remained PCR-positive in 8%, 15%, 43%, and 10% of positive cages, respectively. None of the cages from the autoclave group were PCR-positive for any of the agents after treatment. None of the mice housed in cages in either the autoclave or tunnel wash groups became infected with any of the agents. However, 80%, 60%, and 100% of the pairs of mice housed in untreated cages were PCR-positive for SFB, MNV, and Entamoeba, respectively. None of the mice housed in untreated cages were positive for Helicobacter or Tritrichomonas. Our results suggest that nucleic acids from these bacterial and protozoal organisms may remain in cages after mechanical cage washing, but these nucleic acids are not infectious, and autoclaving is not necessary to prevent transmission.

Mouse kidney parvovirus (MKPV) causes inclusion body nephropathy in severely immunocompromised mice and renal interstitial inflammation in immunocompetent mice. The purpose of this 2-part study was to determine the impact that MKPV may have on preclinical models as it relates to the pharmacokinetics of chemotherapeutics as well as its impact on the adenine diet model of chronic kidney disease. To assess the impact of MKPV on pharmacokinetics of 2 renally excreted chemotherapeutics commonly used in preclinical oncology studies, methotrexate and lenalidomide, blood and urine drug concentrations were measured in MKPV-infected or uninfected immunodeficient NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ (NSG) and immunocompetent C57BL/6NCrl (B6) female mice. Differences in plasma pharmacokinetics were observed for methotrexate, but not for lenalidomide. Differences were most profound between uninfected NSG and B6 mice. The area under the curve (AUC) of methotrexate was 1.5-fold higher in uninfected NSG mice compared to infected NSG mice, 1.9-fold higher in infected B6 mice compared to uninfected B6 mice, and 4.3-fold higher in uninfected NSG mice compared to uninfected B6 mice. Renal clearance of both drugs was not impacted by MKPV infection but was generally lower in NSG mice. To assess the impact of MKPV on the adenine diet model of chronic kidney disease, MKPV-infected and uninfected B6 female mice were fed a 0.2% adenine diet and clinical and histopathologic features of disease were assessed over 8 weeks. Infection with MKPV did not have a significant impact on serum biomarkers of renal function such as BUN, creatinine, and SDMA; urine chemistry; or hemogram. However, infection did impact select histologic outcomes. MKPV-infected mice had significantly more foci of interstitial lymphoplasmacytic infiltrates than uninfected mice after 4 and 8 weeks of diet consumption, and significantly less interstitial fibrosis at week 8. Macrophage infiltrates and renal tubular injury, assessed using various immunohistochemical stains, were similar between groups. Together, these findings indicate that MKPV infection had minimal impact on the renal excretion of 2 chemotherapeutics and serum biomarkers of renal function. However, infection significantly impacted select histologic features of renal disease in the adenine diet model. While MKPV-free mice should be used in biomedical research, it is of the utmost importance in studies evaluating renal histology as an experimental outcome.

Mouse kidney parvovirus (MKPV) causes inclusion body nephropathy in severely immunocompromised mice and renal interstitial inflammation in immunocompetent mice. Here we sought to determine the effects of MKPV on pre-clinical murine models that depend on renal function. To assess the effects of MKPV infection on the pharmacokinetics of 2 renally excreted chemotherapeutic agents, methotrexate and lenalidomide, we measured drug concentrations in the blood and urine of MKPV-infected or uninfected immunodeficient NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ (NSG) and immunocompetent C57BL/6NCrl (B6) female mice. No differences in plasma pharmacokinetics were observed for lenalidomide. However, the AUC of methotrexate was 1.5-fold higher in uninfected NSG mice compared with infected NSG mice, 1.9-fold higher in infected B6 mice compared with uninfected B6 mice, and 4.3-fold higher in uninfected NSG mice compared with uninfected B6 mice. MKPV infection did not significantly affect the renal clearance of either drug. To assess effects of MKPV infection on the adenine diet model of chronic kidney disease, MKPV-infected and uninfected B6 female mice were fed a 0.2% adenine diet, and clinical and histopathologic features of disease were assessed over 8 wk. MKPV infection did not significantly alter urine chemistry results, hemogram findings, or serum concentrations of BUN, creatinine, or symmetric dimethylarginine. However, infection did influence histologic outcomes. As compared with uninfected mice, MKPV-infected mice had more interstitial lymphoplasmacytic infiltrates after 4 and 8 wk of diet consumption and less interstitial fibrosis at week 8. Macrophage infiltrates and renal tubular injury were similar between in infected and uninfected mice. These findings indicate that MKPV infection had minimal effects on the renal excretion of 2 chemotherapeutics and on serum biomarkers of renal function. However, infection significantly influenced two histologic features of the adenine diet model of chronic renal disease. MKPV-free mice are critically important in studies evaluating renal histology as an experimental outcome.