Effects of Buprenorphine Treatment on Influenza Pathogenesis in the Ferret (Mustela putorius furo)

Key considerations to improve the normalization, interpretation and reproducibility of morbidity data in mammalian models of viral disease

Viral pathogenesis and therapeutic screening studies that utilize small mammalian models rely on the accurate quantification and interpretation of morbidity measurements, such as weight and body temperature, which can vary depending on the model, agent and/or experimental design used. As a result, morbidity-related data are frequently normalized within and across screening studies to aid with their interpretation. However, such data normalization can be performed in a variety of ways, leading to differences in conclusions drawn and making comparisons between studies challenging. Here, we discuss variability in the normalization, interpretation, and presentation of morbidity measurements for four model species frequently used to study a diverse range of human viral pathogens - mice, hamsters, guinea pigs and ferrets. We also analyze findings aggregated from influenza A virus-infected ferrets to contextualize this discussion. We focus on serially collected weight and temperature data to illustrate how the conclusions drawn from this information can vary depending on how raw data are collected, normalized and measured. Taken together, this work supports continued efforts in understanding how normalization affects the interpretation of morbidity data and highlights best practices to improve the interpretation and utility of these findings for extrapolation to public health contexts.

Effects of Extended-Release Buprenorphine on Mouse Models of Influenza

Mice are widely used as small animal models for influenza infection and immunization studies because of their susceptibility to many strains of influenza, obvious clinical signs of infection, and ease of handling. Analgesia is rarely used in such studies even if nonstudy effects such as fight wounds, tail injuries, or severe dermatitis would otherwise justify it because of concerns that treatment might have confounding effects on primary study parameters such as the course of infection and/or the serological response to infection. However, analgesia for study-related or -unrelated effects may be desirable for animal welfare purposes. Opioids, such as extended-release buprenorphine, are well-characterized analgesics in mice and may have fewer immune-modulatory effects than other drug classes. In this study, BALB/c and DBA/2 mice were inoculated with influenza virus, and treatment groups received either no analgesics or 2 doses of extended-release buprenorphine 72 h apart. Clinical signs, mortality, and influenza-specific antibody responses were comparable in mice that did or did not receive buprenorphine. We therefore conclude that extended-release buprenorphine can be used to alleviate incidental pain during studies of influenza infection without altering the course of infection or the immune response.