Distribution of Pneumococcal Surface Protein A (PspA) Types among Streptococcus pneumoniae causing systemic infections in argentinian children under 5 years old

REGUEIRA M; CALLEJO R; PACE J; MOLLERACH M; DI FABIO JL; HOLLINGSHEAD S; BRILES D

Orlando, USA

Congreso; 101st General Meeting of the American Society for Microbiology; 2001

American Society for Microbiology

Streptococcus pneumoniae is a major cause of morbidity and mortality worldwide. The lack of efficacy of the currently used poysaccharide vaccines in children under than 2 yers old have prompted the investigation of alternative formulations. One current approach under consideration is the use immunogenic proteins that would offer a broader range of protection and provide a memory response. PspA is an antigenically variable virulence factor found on all strains of pneumococci and has been extensively examined for its suitability as vaccine candidate. PspA has a signal peptide typical of secreted proteins and the amino-terminal half of the mature protein consist of a highly charged a -helical domain sequence variation in this region accounts for the observed antigenic variations in PspA from different families. The aim of this work was to study the distribution of PspA families among argentinian invasive isolates recovered from children under 5 years old. We studied 94 isolates recovered between 1995 and 1999 belonging to the most frequent capsular types recovered in Argentina. PspA family was determined by PCR, using LSM12 primer derived from the sequence coding for the leader peptide (a conserved region) and specific primers to the families 1 and 2 (SKH63 and SKH52) and by dot-blot with monoclonal antibodies anti-family 1 and anti-family 2. Seventy eight isolates could clearly be asigned to Family 1 (60%, n=47) or Family 2 (39%, n=31) by both methods. Seven isolates were classified only by one method because they gave positive reaction for both families by the other. Seven isolates could not be classified in any of the families because positive results were obtained for the two families by both methods.