Effects of Respiratory Syncytial Virus Infection on Dynamic Changes of Airway Hyperresponsiveness in Ovalbumin-Induced Asthma in Mice

Objective To investigate the effects of respiratory syncytial virus(RSV) infection on the dynamic changes of airway hyperresponsiveness(AHR) in ovalbumin(OVA)-induced asthma in mice.Methods 60 BALB/c female mice were randomly divided into PBS control group(A group,n=6),OVA group,OVA/RSV group,dexamethasone group(D group,n=6).Kinetics of AHR of OVA group mice was carried out on day 21,25,29 and 33(B1,B2,B3,B4 groups,n=6),and the same with the OVA/RSV group(C1,C2,C3,C4 groups,n=6).The mouse asthma model was established by OVA-sensitization of intraperitoneal injection and repeated inhalation of OVA while the mice in OVA/RSV group were treated with combined intranasal inoculation with RSV(1.0×106 pfu/mL in 50 μL).Airway resistance of expiring phase(RL) and compliance of throax and lung(CTL) with different doses of acetylcholine(Ach) were measured.Lung tissue sections were stained with hematoxylin and eosin(HE) and periodic acid-Schiff(PAS) for general morphology.Results Compared with B1 group,RL increased and CTL decreased in C1 group when Ach dose is above 5 g/L(P0.05,respectively),and the effects prolonged(6 d,10 d after challenge with OVA,respectively) much more than B1 group(2 d after challenge with OVA).Compared with C1 group,RL decreased and CTL increased in D group and the infiltration of inflammatory cells was obviously alleviated in C1 group after treatment with dexamethasone.Conclusions Airway hyperresponsiveness increases obviously in OVA-sensitized and RSV-infected mice.The prolonged increase in RL and decrease in CTL(6 d,10 d,respectively)may imply that RSV infection aggravates airway inflammation.The small airway inflammation may play a critical role in the persistence of airway hyperresponsiveness.