Autolysin (lytA) recombinant protein: a potential target for developing vaccines against pneumococcal infections.

Purpose: N-acetylmuramoyl-l-alanine amidase known as lytA, is an immunogenic protein that plays an important role in the pathogenesis of . It is highly conserved among strains and is absent among other species. In the present study, the level of antibodies against the lytA recombinant protein was evaluated in healthy individuals' sera.

Materials And Methods: DNA was extracted from ATCC 49619 to amplify A gene by polymerase chain reaction assay. The lytA amplicon and ET28a vector were separately double digested using -1 and 1 restriction enzymes and then ligated together with ligase enzyme. The recombinant plasmid was expressed in BL21 strain and the lytA recombinant protein purified using nickel-nitrilotriacetic acid affinity chromatography. Western blot was carried to detect lytA recombinant protein. Sixty healthy individual's sera (at three age groups: group 1, <2; group 2, 2-40; and group 3, 60-90 years old) were collected and the titers of anti-lytA antibodies were determined.

Results: The A gene was highly expressed in BL21 host. The recombinant lytA protein was purified and confirmed by western blotting. Tukey test analysis showed that there were no significant differences among the age groups considering the anti-lytA titer of 10. However, at the anti-lytA titer of 60, significant differences were observed between group 1 vs. group 2 (p<0.001); group 1 vs. group 3 (p=0.003), and group 2 vs. group 3 (p=0.024).

Conclusion: The lytA protein seems to be a highly immunogenic antigen and a potential target for developing vaccines against pneumococcal infections.