J Virol

J Virol. numerous stages of contamination and being the antigenic determinants of a number of other bacteria, such as and protein made up of IgA-binding motif.6 About 30% of GBS possess the gene which can be predominantly found in the strains of serotypes I and II.7 The ScaAB protein is the major surface lipoprotein similar to the lipoprotein receptor-associated antigen I (LraI) family..8,9 This protein is presented on the surface of gram-positive pathogens and closely related to PsaA protein of which is considered a protein-based vaccine candidate against pathogenic pneumococci which are the most common cause of community-acquired pneumonia.10 The ScpB1 protein represents the portion of C5a peptidase, which is contained among 100% of strains of group A and B streptococci, thus providing a universal target for vaccines against pathogenic streptococci.11 Stv protein is a portion of the glycan-binding protein and adhesion SspB1 which can be found in about one-third of highly pathogenic GBS strains predominantly circulating throughout Russia. Immunization with this protein selectively directs the immune response against the highly virulent GBS strains and is able to activate the cross-reacting antibody against group A streptococci surface proteins.12 The complex of 4 streptococcal antigens included in the composition of recombinant GBS vaccine will contribute to the formation MLN9708 of protection against numerous determinants of bacterial pathogenicity, regardless of their functional state. In a previous study, we have shown that associated intranasal immunization of outbred mice using live attenuated influenza vaccine (LAIV) of H7N3 subtype and 4 GBS recombinant polypeptides was effective against pulmonary contamination with five hundred 50% mouse infectious doses (MID50) of avian A/mallard/Netherlands/12/00(H7N3) or 100 MID50 A/PR8/34(H1N1) influenza followed by GBS serotype II secondary infection.13 In this study, we evaluated whether immunity generated against H7N3 LAIV and GBS polypeptides can protect against H7N9 influenza contamination followed by GBS burden. We also made an attempt to reveal the role of some causes of innate and adaptive immunity in such protection. Although avian influenza A(H7N9) is usually infrequent complicated by streptococcal secondary infection,10 new animal models of viral-bacterial interactions can be applied for further study of vaccines against human infections. Methods Viruses and vaccine preparations The reassortant influenza computer virus A/17/Mallard/Netherlands/00/95(H7N3) (LAIV) was provided from your Virology Department, Institute of Experimental medicine (Saint Petersburg, Russia) collection of viruses. The A/Shanghai/2/2013(H7N9) CDC-RG influenza computer virus (H7N9) was provided by the Centers for Disease Control and prevention, USA. The viruses were propagated in embryonated chicken eggs (CE) and stored at ?70C. The group B streptococcus vaccine (GBSV) contained GBS recombinant polypeptides P6 (30 kDa), ScaAB (35 kDa), ScpB1 (43-kDa), and Stv (130 kDa) which were expressed in and purified as explained earlier.14 Immunization The 8- to-10-week-old female outbred mice were provided by the laboratory breeding nursery of the Russian Academy of Sciences (Rappolovo, Leningrad Region). Groups of mice (54 animals in a group) were lightly anesthetized with ether and intranasally vaccinated with 50 L divided equally per nostril using the following preparations: (1) LAIV contained 1 107 50% egg infectious dose (EID50) of the H7N3 vaccine computer virus; (2) GBSV contained the mix of P6, ScaAB, ScpB1, and Stv LAMP3 recombinant MLN9708 polypeptides (5 g each, 20 g total); 3) mixed LAIV + MLN9708 GBSV vaccine including 1 107 EID50 of H7N3 computer virus and GBSV; and (4) control animals were inoculated with phosphate-buffered saline (PBS). The mice were immunized twice at an interval of 21 days (Physique 1). Open in a separate window Physique 1 Mouse study design. GBS indicates group B streptococcus. Three weeks after vaccination and after revaccination, sera were collected from ether-anesthetized mice via submandibular plexus. Nasal secretions were collected from mice after intraperitoneal administration of 0.1 mL of a 0.5% pilocarpine solution (Sigma-Aldrich, St. Louis, MO, USA) into the tubes made up of 0.001 M of serine protease inhibitor phenylmethylsulfonyl fluoride. Sera and nasal samples were stored at ?20C. All invasive procedures involving animals were performed under ether anesthesia, according to the Rules Laboratory Practice Ministry of Health of the Russian Federation No. 708 n. Hemagglutination-inhibition assays For hemagglutination-inhibition (HI) assay, sera were.