Establishment and comparison of Actinobacillus pleuropneumoniae experimental infection model in mice and piglets.

Actinobacillus pleuropneumoniae (APP) causes porcine pleuropneumonia, a disease responsible for substantial losses in the worldwide pig industry. In this study, outbred Kunming (KM) and Institute of Cancer Research (ICR) mice were evaluated as alternative mice models for APP research. After intranasal infection of serotype 5 reference strain L20, there was less lung damage and a lower clinical sign score in ICR compared to KM mice. However, ICR mice showed more obvious changes in body weight loss, the amount of immune cells (such as neutrophils and lymphocytes) and cytokines (such as IL-6, IL-1β and TNF-α) in blood and bronchoalveolar lavage fluid (BALF). The immunological changes observed in ICR mice closely mimicked those found in piglets infected with L20. While both ICR and KM mice are susceptible to APP and induce pathological lesions, we suggest that ICR and KM mice are more suitable for immunological and pathogenesis studies, respectively. The research lays the theoretical basis for determine that mice could replace pigs as the APP infection model and it is of significance for the study of APP infection in the laboratory.