Pre-existing atopy protects mice from paramyxoviral respiratory infection weight loss

Abstract

Abstract Severe paramyxoviral infections early in life have been associated with development of asthma and allergies; respiratory viral infections are known to exacerbate asthma. We have a mouse model of a severe paramyxviral respiratory infection using murine parainfluenza virus 1, Sendai virus (SeV). C57BL6 mice inoculated with SeV develop a severe acute infection demonstrated by significant weight loss over 8–10 days. The mice recover and are left with long-lasting airway hyper-reactivity and mucous cell metaplasia. Exposure to a non-viral antigen during the acute infection leads to IgE production against the non-viral antigen (allergic sensitization). While this model provides an explanation for development of allergies and asthma, it is not known whether being atopic before viral infection alters the disease state. To address this, we intranasally sensitized and challenged C57BL6 mice with house dust mite extract (HDM) or PBS, and one week later inoculated the mice with 2×105 pfu SeV or ultraviolet light inactivated SeV (UV-SeV). All UV-SeV groups lost no weight. SeV infection in PBS sensitized/challenged (PBS/PBS/SeV) mice led to a 10.8+/−2.5% weight loss from baseline (mean+/−SEM, n=4); surprisingly, HDM sensitized and challenged mice lost no weight with SeV infection (−1.7+/−0.6% weight loss, n=4, p=0.0022 versus PBS/PBS/SeV). Mice HDM sensitized but not challenged loss 10.8+/−1.6% weight with SeV infection (n=4, p>0.99 versus PBS/PBS/SeV). Whether the weight loss protection from HDM sensitization/challenge alters the antiviral immune response and/or protects against post-viral atopic disease is being investigated. These data suggest atopy may protect against symptoms of a severe paramyxoviral respiratory infection.