Dot Blot para determinar la identidad antigénica en vacunas conjugadas contra Streptococcus pneumoniae serotipo 19F

Regulatory authorities recommend the use of NMR (Nuclear Magnetic Resonance) techniques or serological techniques to determine the identity of antigens on the conjugate vaccines. Due to the emergence of multivalent conjugate vaccines it has become necessary to use immunochemical techniques with the use of monoclonal antibodies (MAbs) in order to increase the sensitivity in determining the identity of such antigen in the conjugate vaccines. The aim of this study was to establish the optimal working conditions that would allow using Dot Blot technique to determine the identity of antigens in conjugate vaccines against Streptococcus pneumoniae serotype 19F. The incubation times, the possibility of using different reagents for blocking step were studied for this purpose; also the optimal concentrations of MAbs and active pharmaceutical ingredients (APIs), as well as the volumes of optimal application for APIs and vaccines. A monoclonal antibody against the capsular polysaccharide of S. pneumoniae serotype 19F (PsC 19F) was used. The samples used in this work, were samples of lots of APIs of monovalent conjugated PsC 19F and lots of Cuban heptavalent conjugate vaccine candidate against pneumococcus. The results showed that for the determination of the antigenic identity were optimal volumes of 10 µL of monovalent conjugate samples at 125 µg/mL and equal volume for heptavalent vaccines. For MAb was demonstrated that 1 µg/mL concentration of MAb against the PSC 19F and incubation times of 30 min at 37 °C were sufficient to successfully perform the determinations. In conclusion we can say that were established optimal working conditions to determine the antigenic identity, by Dot Blot, for the capsular polysaccharide of S. pneumoniae serotype 19F present in the APIs of monovalent conjugated and in the heptavalent conjugate vaccines.