Interferon and other proinflamatory cytokine responses in vitro following infection with wild-type and cold-adapted reassortant influenza viruses

Associated virus-bacterial vaccine based on seasonal LAIV and S. pneumoniae chimeric peptide provide protection against post-influenza pneumococcal infection in mouse model

Severe influenza complications are often caused by Streptococcus pneumoniae infection, which presents the most common cause of community-acquired pneumonia. We evaluated in a mouse model an associated virus-bacterial vaccine based on seasonal live influenza vaccines (LAIV) and S. pneumoniae chimeric protein comprising flagellin (PSPF). Intranasal immunization of mice with a complex of trivalent LAIV and PSPF caused an increased release of early cytokines in the lungs of mice. The immunogenicity of LAIV and PSPF in the associated vaccine composition was sometimes decreased compared to each vaccine preparation alone. Nevertheless, only vaccination of mice with LAIV+PSPF significantly reduced lethality and the bacterial load in the lungs in a model of post-influenza bacterial pneumonia. The study of the interactions of influenza viruses with bacterial peptides is important during the development of associated virus-bacterial vaccines intended for the prevention of severe post-influenza bacterial complications.

Assessment of trivalent live influenza vaccines in MDCK cell line

We applied a one-step reverse transcriptase real-time PCR (rRT-PCR) analysis using TaqMan technique to evaluate the infectious titers of vaccine strains containing in trivalent live influenza vaccines (LAIVs). The cold-adapted reassortant influenza viruses A/H1N1 pdm09, A/H3N2, B/Yamagata and B/Victoria, included in the composition of the LAIV in 2015-2016, 2017-2018 and 2018-2019 flu season were studied for reproductive activity in MDCK cells as part of a mono-vaccine and tri-vaccine. For this we have developed a set of specific primers and probes. Method validation was performed using ELISA-test after mouse monoclonal antibodies to hemagglutinin (HA) staining of MDCK monolayer. Influenza B viruses B/Yamagata and B/Victoria were studied in MDCK cells in mono-infection and coinfection with different multiplicity of infection (MOI) using quantitative rRT-PCR.•RT-PCR analysis was adjusted to assess the growth characteristics of cold-adapted reassortant influenza viruses in MDCK cell line. The greatest suppression in the composition of the tri-vaccine was exposed to the H1N1 pdm09 LAIV component.•Influenza B viruses are least suppressed in trivalent LAIV. Influenza viruses B/Yamagata and B/Victoria reproduced as part of a mixed preparation not lower, if not better than as a mono-preparation at an MOI of 0.1. At an MOI of 0.01, the reproduction of both B/Yamagata and B/Victoria in the mixture was reduced compared to mono-vaccine.•The interference of trivalent LAIV vaccine viruses in MDCK cells was minimal at low dilutions. This indicates that it is undesirable to reduce the titers of vaccine viruses, including at the stages of transportation and storage of LAIV.

The safety of attenuated and recombinant nasal influenza vaccines in terms of the development of secondary bacterial superinfection

Introduction. Influenza is a severe viral disease. The most common post-influenza complication is pneumonia. Earlier, we developed an experimental mouse model of viralbacterial pneumonia induced by successive infection with influenza virus and St. aureus, in which lethal synergy between pathogens observed in epidemiological observations was detected.

Aim. To study the effect of the administration of intranasal vaccines, followed by infection with St. pneumoniae on the development and completion of the disease.

Materials and methods. The animals were immunized intranasal with a strain of attenuated cold-adapted live influenza vaccine A/17/California/2009/38 (H1N1)pdm09 (LAIV) and a recombinant vaccine based on virus-like particles HA(Puerto Rico/8/34)- Gag (VLPs). Control groups of animals were infected with virulent strains of influenza virus A/ California/04/2009 (H1N1)pdm09 or A/Puerto Rico /8/34 (H1N1). On the fifth day after intranasal immunization with the vaccine preparations and infection with pathogenic strains, animals were subjected to bacterial infection with a strain of St. pneumoniae. The presence of synergism of vaccine or viral agent with bacterial infection was assessed by survival and weight loss of animals, virus titer and density of bacteria in nasopharyngeal washes and lungs.

Results. It was shown that immunization with vaccine preparations did not lead to increased sensitivity of mice to bacterial infection. Elimination of bacteria from the lungs and nasopharynx in groups immunized with vaccine preparations corresponded to the dynamics in the group of animals immunized by PBS.

Discussion. The results obtained indicate the safety of intranasal immunization with LAIV A/17/California/2009/38 (H1N1)pdm09 and virus-like particles HA (Puerto Rico/8/34)- Gag (VLPs) in terms of enhancing secondary bacterial superinfection caused by St. pneumoniae.

Conclusion. The studied vaccines successfully blocked infections in the lower respiratory tract.

Factors of early protective action of live influenza vaccine combined with recombinant bacterial polypeptides against homologous and heterologous influenza infection

We are developing an associated vaccine based on live influenza vaccine (LAIV) and streptococcal recombinant peptides. The recombinant group B streptococcus (GBS) peptides P6 and ScaAB demonstrated a distinguished immunomodulating effect in THP-1 cells. The increase in IFN 1-alpha expression after ScaAB inoculation was similar to that against LAIV. We immunized mice intranasal using of A/H7N3 LAIV or/and ScaAB peptide. At day 5 after immunization, we detected serum IgM which reacted with non-vaccine influenza viruses. Associated vaccination of mice using LAIV and GBS peptide was the most effective against sub-lethal infection with A/H7N9 influenza virus and against lethal challenge with A/H1N1pdm virus at day 5 after immunization. Not only LAIV but also the ScaAB protected about 20% of the immunized animals against lethal challenge with A/H1N1pdm virus. The early protection was related to increasing type 1 interferons expression in the lungs.

Our results in mice have shown that successful protection against homologous and heterologous influenza infections can be achieved soon after vaccination with either LAIV or LAIV in combination with GBS recombinant peptide. Presumably, such protection may be mediated by non-specific IgM antibodies and an increase in the expression of early cytokines in the airway.

Tackling a novel lethal virus: a focus on H7N9 vaccine development

INTRODUCTION

Avian-origin H7N9 influenza viruses first detected in humans in China in 2013 continue to cause severe human infections with a mortality rate close to 40%. These viruses are acknowledged as the subtype most likely to cause the next influenza pandemic. Areas covered: Here we review published data on the development of H7N9 influenza vaccine candidates and their evaluation in preclinical and clinical trials identified on PubMed database with the term 'H7N9 influenza vaccine'. In addition, a search with the same term was done on ClinicalTrials.gov to find ongoing clinical trials with H7N9 vaccines. Expert commentary: Influenza vaccines are the most powerful tool for protecting the human population from influenza infections, both seasonal and pandemic. During the past four years, a large number of promising H7N9 influenza vaccine candidates have been generated using traditional and advanced gene engineering techniques. In addition, with the support of WHO's GAP program, influenza vaccine production capacities have been established in a number of vulnerable low- and middle-income countries with a high population density, allowing the countries to be independent of vaccine supply from high-income countries. Overall, it is believed that the world is now well prepared for a possible H7N9 influenza pandemic.

Pandemic preparedness with live attenuated influenza vaccines based on A/Leningrad/134/17/57 master donor virus

Continuously evolving avian influenza viruses pose a constant threat to the human public health. In response to this threat, a number of pandemic vaccine candidates have been prepared and evaluated in animal models and clinical trials. This review summarizes the data from the development and preclinical and clinical evaluation of pandemic live attenuated influenza vaccines (LAIV) based on Russian master donor virus A/Leningrad/134/17/57. LAIV candidates of H5N1, H5N2, H7N3, H1N1 and H2N2 subtypes were safe, immunogenic and protected animals from challenge with homologous and heterologous viruses. Clinical trials of the pandemic LAIVs demonstrated their safety and immunogenicity for healthy adult volunteers. The vaccine viruses were infectious, genetically stable and did not transmit to unvaccinated contacts. In addition, here we discuss criteria for the assessment of pandemic LAIV immunogenicity and efficacy necessary for their licensure.

Protection from lethal influenza virus challenge by oral type 1 interferon

The persistence of highly pathogenic avian influenza within wild bird populations has forged interest in control measures to limit a possible human pandemic. We therefore investigated the efficacy of low dose oral administration of IFN-alpha as a potential therapy against influenza infection in a murine model. We have identified an optimal low oral dose of IFN-alpha that when delivered daily as prophylactic therapy protects C57BL/6J mice from a lethal challenge with mouse adapted human influenza virus A/PR/8/34 (H1N1). These results provide strong support for the application of low dose type 1 IFN pretreatment to human influenza control.