441. Evaluation of the protective efficacy of the intranasal conjugated 10-valent pneumococcal vaccine and its role in upper airway colonization in mice
Session: Poster Abstract Session: Pneumococcal Vaccine in Children and Adults
Thursday, October 3, 2013
Room: The Moscone Center: Poster Hall C
Background:

Intranasal or aerosol immunization has been useful for some attenuated live viral vaccines like influenza and measles. The aim of the study was to investigate the protective efficacy of the instranasal 10-valent conjugated pneumococcal vaccine in mice and its role in nasopharyngeal colonization.

Methods:

Female 6 weeks old BALBc mice were used. The 10-valent conjugated pneumococcal vaccine (Synflorix, GSK) was administered by the intranasal route (10 μl) and by subcutaneous injection (10 μl) in 2 groups of 16 mice each, and PBS was administered subcutaneously to 16 mice.

For the survival study, three months following the inoculation, eight mice in the intranasal group, 8 mice of the subcutaneous group and 8 mice of the PBS group were challenged intraperitoneally with 3 x 108 (3 times the LD50, 1 x 108) of 19F Streptococcus pneumoniae  (ATCC 49619). The survival of the mice was recorded.

For the colonization study, three months after inoculation, 8 mice of the intranasal group, 8 of the subcutaneous group and 8 of the PBS group were challenged intranasally with 1 x 107 of 19F Streptococcus pneumoniae  (ATCC 49619). On the third day mice were sacrificed, retrograde nasal washings were performed by transversal section of the trachea, 100 μl were collected and plated on blood agar to evaluate the nasopharyngeal colonization.

Results:

The first day following bacterial challenge, 37.5% of the subcutaneous group, 25% in the intranasal group and 37.5% of the PBS group survived. From day 4 and after, the subcutaneous and intranasal group had a 12.5% of survival compared to 0% in the PBS group.

For the colonization studies, the PBS group presented countless colony forming units of Streptococcus pneumoniae 19F whereas the subcutaneous group had (mean + SD) 282 + 177 colony forming units and the intranasal group had 274 + 152 colony forming units.

Conclusion:

Mice immunized intranasally and subcutaneously with a ten valent pneumococcal conjugate vaccine had a modest, but similar survival after lethal intraperitoneal challenge with type 19F pneumococci. However, both immunization routes significantly reduced the nasopharyngeal carriage. Further studies are warranted to evaluate the role of mucosal vaccination against encapsulated respiratory bacteria with conjugate vaccines.

Irma Patricia Ortega Espinoza, B Sc.1, Miguel Leonardo Garcia Leon, MSc2, Jose Ignacio Santos Preciado, MD2 and Rosa Maria Wong Chew, MD DSc3, (1)Experimental Medicine, Universidad Nacional Autonoma De Mexico, Mexico, Mexico, (2)Experimental Medicine Department, Universidad Nacional Autonoma de Mexico, DF, Mexico, (3)Experimental Medicine Department, Universidad Nacional Autonoma De Mexico, DF, Mexico

Disclosures:

I. P. Ortega Espinoza, None

M. L. Garcia Leon, None

J. I. Santos Preciado, None

R. M. Wong Chew, GSK: Speaker's Bureau, Speaker honorarium

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