Vaccine 28 (2010) 3071–3075 Contents lists available at ScienceDirect Vaccine journal homepage: www.elsevier.com/locate/vaccine Short communication Concomitant administration of recombinant PsaA and PCV7 reduces Streptococcus pneumoniae serotype 19A colonization in a murine model Melissa J. Whaley ∗ , Jacquelyn S. Sampson, Scott E. Johnson, Gowrisankar Rajam, Annie Stinson-Parks, Patricia Holder, Erica Mauro, Sandra Romero-Steiner, George M. Carlone, Edwin W. Ades Division of Bacterial Diseases, Center of Disease Control and Prevention, 1600 Clifton Rd NE, MS G-05, Atlanta, GA 30333, United States article info Article history: Received 15 October 2009 Received in revised form 12 February 2010 Accepted 17 February 2010 Available online 4 March 2010 Keywords: Pneumococcal vaccines Non-interference Expanded vaccine coverage abstract A murine colonization model was used to determine the effect of co-administering 7-valent polysaccharide-protein conjugate vaccine and pneumococcal surface adhesin A. Mice were challenged intranasally with either PCV7 serotypes, 4 or 14, or a non-PCV7 serotype, 19A. Post-challenge samples were evaluated for IgG antibody levels, opsonophagocytic activity, and nasopharyngeal colonization. No interference was observed between immune responses from the concomitant and individual immuniza- tions. Concomitant immunizations reduced carriage for tested serotypes; largest reduction was observed for 19A. From these mouse studies, co-administering pneumococcal antigens appear to expand cover- age and reduce colonization against a non-PCV7 serotype without inhibiting immunogenicity to other serotypes. Published by Elsevier Ltd. 1. Introduction The introduction of 7-valent polysaccharide-protein conjugate vaccine (PCV7) in 2000 has successfully reduced the incidence of invasive pneumococcal disease (IPD) due to vaccine serotypes (VT) among young children and adults in the United States [1]. The decline in carriage of VT may have allowed non-vaccine serotypes (NVT) to fill the niche and cause disease, the phenomena known as serotype replacement [2–4]. By 2004, 88% of IPD among children <5 years old was due to NVT [2]. Of the NVT, serotype 19A was predom- inant [2]. Serotype 19A isolates were identified in IPD cases in the United States [5–7] and Korea [8] with increased non-susceptibility to antimicrobials. Even though serotype 19A was known to cause IPD prior to the use of PCV7 [2,9], clonal expansion of serotype 19A was also reported [10,11]. As a method to protect against serotype replacement disease, pneumococcal conjugate vaccines (PCV) are increasing in their valences [3,12,13]. The distribution of pneumococcus constantly changes and varies geographically, complicating the construction and implementation of new PCV [11,14]. Although pneumococ- cal (Pnc) polysaccharides are considered the major virulence factor, Pnc proteins in a vaccine formula could provide serotype- independent protection [14]. The evaluation of these protein-based vaccines, for the most part, has been limited to the mouse model [15]. Briles et al. observed enhanced reduction of nasopharyngeal ∗ Corresponding author. Tel.: +1 404 639 3920; fax: +1 404 639 4518. E-mail address: mwhaley@cdc.gov (M.J. Whaley). colonization in mice immunized with the Pnc surface protein A (PspA) and Pnc surface adhesin A (PsaA) in comparison to mice immunized with PspA or PsaA alone [16]. PsaA, a common Pnc protein, has been shown to be immunogenic and reduce nasopha- ryngeal carriage in a mouse model [16–18]. Previous studies also showed that PspA mixed with pneumolysin or the combination of Pnc histidine triad proteins, PhtB (BVH-11) and PhtE (BVH-3) enhances the protection against pneumonia in the mouse model [19–22]. More than one mechanism of defending against infection is targeted as a result of combining proteins; however, no other pneumococcal antigen as of yet can elicit comparable protection to that of Pnc polysaccharides in conjugate form [22]. In our study, we co-administered PCV7 and rPsaA to increase serotype coverage of PCV7. We evaluated the immune responses and reduction in carriage of PCV7 serotypes 4 and 14, and non-PCV7 serotype 19A in mice. 2. Material and methods 2.1. Bacterial isolates and growth conditions Streptococcus pneumoniae serotype 4 (CSF isolate DS2341-94), 14 (blood isolate D2232-92) and 19A (blood isolate DS3842-03) were used. All strains were provided by the Streptococcus Refer- ence Laboratory at the Centers for Disease Control and Prevention. Serotypes were confirmed through latex agglutination and capsu- lar swelling (Quellung reaction) tests [18]. For PCV7 serotypes 4 and 14, stocks were prepared as before [18,23]. To optimize col- onization, the transparent phenotype of the serotype 19A strain 0264-410X/$ – see front matter. Published by Elsevier Ltd. doi:10.1016/j.vaccine.2010.02.086