Bacillus Calmette-Guerin (BCG) vaccination can protect animals from
asthma, but the effect of BCG on childhood
asthma prevention is controversial in humans. To verify the hypothesis that the BCG anti-
asthma effect in childhood might be reversed by a respiratory
virus infection, newborn BALB/c mice were divided into five groups. Control and
ovalbumin (OVA) groups were mock vaccinated and mock infected. The BCG/OVA group was BCG vaccinated and mock infected. The respiratory syncytial virus (RSV)/OVA group was mock vaccinated and RSV infected. The BCG/RSV/OVA group was BCG vaccinated and RSV infected. Except for the control group, all groups underwent OVA sensitization and challenge.
Airway hyperresponsiveness (AHR) was measured after challenge and cells in bronchoalveolar lavage fluid (BALF) were counted.
Cytokines in BALF and serum OVA-specific
IgE were detected by ELISA and inflammatory characteristics of lung sections were scored. Mice with neonatal BCG vaccination (BCG/OVA group) were significantly protected from BALF
eosinophilia, AHR to
methacholine, peribronchiolitis, alveolitis, and peribronchial
eosinophilia in comparison with the OVA, RSV/OVA, and BCG/RSV/OVA groups. AHR in the OVA group was greater than in the BCG/OVA group but lower than in the RSV/OVA and BCG/RSV/OVA groups. No significant differences in BALF
eosinophilia, AHR, and
lung inflammation were found between the RSV/OVA and BCG/RSV/OVA groups. The impact of BCG vaccination on anti-
asthma in mice was not dependent on
interferon-gamma,
IL-4, and
IL-10 levels. The results suggested that
RSV infection can reverse the anti-
asthma effect of neonatal BCG vaccination in BALB/c mice.