Purpose: Respiratory syncytial virus (RSV) is the most common cause of severe respiratory tract infection in infants. The aim was to identify host defence components in nasopharyngeal aspirate (NPA) from infants with RSV infection and to study the expression of the novel 25 kDa innate immunity protein SPLUNC1.
Experimental design: NPAs from infants were analyzed with 2-DE and MS in a pilot study. The levels of SPLUNC1 were analyzed with immunoblotting in 47 NPAs, admitted for RSV diagnosis.
Results: Totally, 35 proteins were identified in NPA, including several innate immunity proteins such as group X phospholipase A(2) , different S100 proteins and SPLUNC1. In addition, a new truncated 15 kDa form of SPLUNC1 was identified that was detected in about 50% of the aspirates admitted for RSV diagnosis. RSV-positive boys had significantly less 25 kDa SPLUNC1 than RSV-negative boys while there were no significant differences among girls.
Conclusions and clinical relevance: Several important innate immunity proteins were identified in NPA. Notably, a new truncated form of the newly suggested anti-bacterial protein SPLUNC1 was found. It is possible that a decrease in SPLUNC1 in the upper airways may increase the risk for severe pneumonia in boys.
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