Effectiveness of inactivated influenza vaccine for prevention of otitis media in children

Effectiveness of inactivated influenza vaccine for prevention of otitis media in children. the NA component is rarely measured (18). Without consistent detection of immunity generated toward the NA (27), we are left unaware of the impact that annual vaccination MI 2 has on immunity toward the NA component within the population (29). Secondary bacterial infections, the majority of which are associated with (21, 23, 25, 32), make a significant contribution to deaths during influenza epidemics (5, 28, 30) and pandemics (1, 19, 22), through a phenomenon known as excess mortality. Population-based studies have indicated that vaccination against influenza virus greatly reduces the incidence of (4, 24), which would implicate vaccination against influenza as a method for limiting secondary bacterial complications. Evidence that prevention of influenza virus NA activity can significantly limit the severity of secondary bacterial infections (20) led us to hypothesize that matching the NA component in annual vaccines will limit secondary bacterial MI 2 complications. To test this hypothesis, 6- to 8-week-old female BALB/cJ mice (Jackson Laboratories, Bar Harbor, ME) were vaccinated with formalin-inactivated influenza vaccines created using an 8-plasmid reverse genetics system as described previously (10, 11, 14, 15). Viruses used to create MI 2 these vaccines were generated using HA and NA genes from influenza virus strains A/Hong Kong/1/68 (HK; GenBank accession numbers “type”:”entrez-nucleotide”,”attrs”:”text”:”AF348176″,”term_id”:”14009691″,”term_text”:”AF348176″AF348176 and “type”:”entrez-nucleotide”,”attrs”:”text”:”AF348184″,”term_id”:”14009707″,”term_text”:”AF348184″AF348184, respectively) and A/Sydney/5/97 (SY; “type”:”entrez-nucleotide”,”attrs”:”text”:”AF180584″,”term_id”:”6552527″,”term_text”:”AF180584″AF180584 and “type”:”entrez-nucleotide”,”attrs”:”text”:”AJ291403″,”term_id”:”12038911″,”term_text”:”AJ291403″AJ291403, respectively) in combinations where the HA and NA genes were a match (HK/HK and SY/SY) and where the HA and NA were mismatched (HK/SY and SY/HK). As detailed previously, the HA gene for HK HA differed from the GenBank sequence at position N153I (A458T) (14). The remaining six genes (PB1, PB2, PA, NP, M, and NS) in all viruses created were derived from A/Puerto Rico/8/34 (kindly provided by Erich Hoffmann and Robert G. Webster). Rescued viruses were propagated in 10-day-old embryonated chicken eggs, concentrated, and purified over sucrose gradients, and the HA content was quantitated as described previously (14, 15). Mice were vaccinated with 3 g HA in a 100-l volume delivered intramuscularly (i.m.) in the right rear quadriceps two or three times at 4-week intervals, using 2 mg/ml alum (Reheis, Berkeley Heights, NJ) as an adjuvant (12). Three weeks after inoculation, sera were collected from isoflurane-anesthetized mice via the orbital plexus and treated with receptor-destroying enzyme (RDE) as described previously (14, 15), and anti-HA antibodies were quantitated using a hemagglutination inhibition (HI) assay (Fig. ?(Fig.1).1). Chicken red blood cells (Rockland Immunochemicals, Inc., Gilbertsville, PA) were used for HI assays, and titers are reported as the final serum dilution that demonstrates inhibition of hemagglutination. As predicted, HI titers detected using viruses expressing HK HA were significantly increased when sera obtained from HK HA-vaccinated mice were compared to sera collected from SY HA-vaccinated mice. Similarly, SY HA-expressing viruses demonstrated increased HI titers when sera from SY HA-vaccinated mice were included in the HI assay, compared to sera from HK HA-vaccinated mice. Mice vaccinated with alum alone did not develop detectable levels of anti-HA immunity. Interestingly, after two inoculations, mice that received inactivated influenza virus (IIV) preparations containing the HK NA demonstrated significantly reduced HI titers compared to IIV preparations that contained the SY NA (data not shown). Mice in these groups received a third inoculation with IIV to enhance the immunity toward the HA component of these vaccines, and the reported results for all immune assays are from sera collected 1 week prior to inoculation MI 2 with virus in our challenge model. Open in a separate window FIG. 1. Hemagglutination inhibition titers after inoculation of mice with IIV preparations. Influenza hemagglutinin-reactive antibodies were Mouse monoclonal to CD4.CD4 is a co-receptor involved in immune response (co-receptor activity in binding to MHC class II molecules) and HIV infection (CD4 is primary receptor for HIV-1 surface glycoprotein gp120). CD4 regulates T-cell activation, T/B-cell adhesion, T-cell diferentiation, T-cell selection and signal transduction detected for groups of mice that received IIV preparations composed of HK/SY (= 19), HK/HK (= 19), SY/SY (= 20), or.