Effects of Pelleting, Irradiation, and Autoclaving of Rodent Feed on MPV and MNV Infectivity

Abstract

Murine norovirus (MNV) and mouse parvovirus (MPV) are among the most common adventitial viruses seen in laboratory mice, and infections arise in barrier facilities despite rigorous biosecurity programs. Some authors have implicated nonsterilized feed as a source of MPV in rodent facilities, but none have conclusively documented viral particles in the feed. In this study, we hypothesized that both viruses can resist the pelleting process but not subsequent irradiation or autoclaving, thus revealing a potential source of outbreaks in rodent facilities. To test this hypothesis, we contaminated powdered feed with 10-fold concentrations of MNV and MPV and fed it to both Swiss Webster (SW) and C57BL/6NTac (B6) mice to determine a 'powdered ID 50 ' according to seroconversion over a 28-d period. We repeated the experiment by using powdered feed that we contaminated with increasing viral doses (as no. of powdered ID 50) and subsequently pelleted; from these results, we determined a 'pelleted ID 50 .' Finally we assessed the effect of irradiation and autoclaving on contaminated pellets by using the same experimental design. The powdered ID 50 was relatively low and identical in both mouse strains (2.51 × 10 2 pfu) for MNV but higher in B6 (copy number, 3.20 × 10 6) than SW (3.98 × 10 4 copies) for MPV. As hypothesized, mice were infected by contaminated rodent feed despite the pelleting process. Indeed, pelleting resulted in a 1-to 2-log increase in ID 50 in both strains for MNV and MPV. Irradiation and autoclaving of infected pellets effectively prevented seroconversion of mice exposed to all doses of MNV, whereas a single mouse seroconverted at the highest dose of MPV (1.35 × 10 7 copies). These data suggest that both MNV and MPV remain infectious after conditions reproducing the rodent chow pelleting process and that nonsterilized rodent chow might be a source of viral outbreaks.

Kelayakan dasar UMKM pengolahan ikan di Kecamatan Pulau Banyak, Aceh Singkil

“…UMKM yang mudah dimasuki oleh hewan menandakan telah melakukan penyimpangan kritis. Beberapa hasil penelitian menyebutkan tikus (Adams et al, 2019) dan semut jenis Technomyrmex difficilis dan Solenopsis geminata (Simothy et al, 2018) merupakan agen penyebab kontaminasi patogen pada pangan.…”

High‐Coverage Metabolome Analysis Reveals Significant Diet Effects of Autoclaved and Irradiated Feed on Mouse Fecal and Urine Metabolomics

“…[ 1–5 ] To ensure reproducibility and reduce variability, rodent feed is sterilized to eliminate the introduction of potentially pathogenic microorganisms that might result in clinical disease or subclinical infections that could affect physiologic responses. [ 6–10 ] Autoclave and irradiation are two main sterilization techniques available for rodent feed, and both methods can alter its chemical composition. [ 8–14 ] Irradiation led to significant changes in phytochemicals, oxidized lipids, and linoleic acid‐derived products, [ 11,15 ] while autoclaving rodent feed can affect vitamins A, B1, D content, and acrylamide concentrations.…”

“…[ 6–10 ] Autoclave and irradiation are two main sterilization techniques available for rodent feed, and both methods can alter its chemical composition. [ 8–14 ] Irradiation led to significant changes in phytochemicals, oxidized lipids, and linoleic acid‐derived products, [ 11,15 ] while autoclaving rodent feed can affect vitamins A, B1, D content, and acrylamide concentrations. [ 9,10,13,14 ] These chemical changes to dietary components in rodent feed may in turn cause metabolomic changes of biospecimens collected from mice or rats fed different diets (i.e., feed‐related diet effects).…”