Objective To evaluate the effects of intervention by polysaccharide nucleic acid fraction of BCG(BCG-PSN),bacillus calmette-guerin (BCG) inoculation in preventing infants with acute bronchiolitis from asthma and explore its mechanism .

• 目的:评价卡介菌多糖核酸、卡介苗经皮接种治疗对毛细支气管炎患儿日后发生哮喘的预防效果并探讨其作用机制。