Live attenuated influenza H7N3 vaccine is safe, immunogenic and confers protection in animal models

Background: In 2003 the outbreak of highly pathogenic H7 avian influenza occurred in the Netherlands. The avian H7 virus causing the outbreak was also detected in humans; one person died of pneumonia and acute respiratory distress syndrome. Our paper describes preclinical studies of a H7N3 live attenuated influenza A vaccine (LAIV) candidate in various animal models. Objectives: To study safety, immunogenicity and protection of H7N3 LAIV candidate in mice, ferrets and chickens. Methods: The vaccine was generated by a classical reassortment between low pathogenicity A/mallard/Netherlands/12/00 (H7N3) virus and A/Leningrad/134/17/57 (H2N2) master donor virus (MDV). Results: Immunogenicity was found that H7N3 LAIV was similar to the MDV in terms of replication in the respiratory organs of mice and failed to replicate in mouse brains. One dose of a H7N3 LAIV elicited measurable antibody response and it was further boosted with a second vaccine dose. Immunization of mice with H7N3 LAIV provided protection against infection following a homologous challenge with wild type H7N3 virus. Attenuated phenotype of H7N3 LAIV has been confirmed in ferrets. Immunogenicity and protective efficacy of H7N3 LAIV in ferrets were also demonstrated. The vaccine protected animals from subsequent infection with wild type H7N3 virus. The results of histopathology study revealed that inoculation of H7N3 LAIV in ferrets did not cause any inflammation or destructive changes in lungs. Lack of H7N3 LAIV replication in chicken demonstrated complete safety of this preparation for poultry. Conclusion: Results of our study suggest that new H7N3 LAIV candidate is safe, immunogenic and protects from homologues influenza virus infection in mice and ferrets. © Rekstin et al

Immunogenicity and Cross Protection in Mice Afforded by Pandemic H1N1 Live Attenuated Influenza Vaccine Containing Wild-Type Nucleoprotein

Since conserved viral proteins of influenza virus, such as nucleoprotein (NP) and matrix 1 protein, are the main targets for virus-specific CD8+ cytotoxic T-lymphocytes (CTLs), we hypothesized that introduction of the NP gene of wild-type virus into the genome of vaccine reassortants could lead to better immunogenicity and afford better protection. This paper describes in vitro and in vivo preclinical studies of two new reassortants of pandemic H1N1 live attenuated influenza vaccine (LAIV) candidates. One had the hemagglutinin (HA) and neuraminidase (NA) genes from A/South Africa/3626/2013 H1N1 wild-type virus on the A/Leningrad/134/17/57 master donor virus backbone (6: 2 formulation) while the second had the HA, NA, and NP genes of the wild-type virus on the same backbone (5: 3 formulation). Although both LAIVs induced similar antibody immune responses, the 5: 3 LAIV provoked greater production of virus-specific CTLs than the 6: 2 variant. Furthermore, the 5: 3 LAIV-induced CTLs had higher in vivo cytotoxic activity, compared to 6: 2 LAIV. Finally, the 5: 3 LAIV candidate afforded greater protection against infection and severe illness than the 6: 2 LAIV. Inclusion in LAIV of the NP gene from wild-type influenza virus is a new approach to inducing cross-reactive cell-mediated immune responses and cross protection against pandemic influenza. © 2017 Andrey Rekstin et al

Centrifugal compressor impeller loading factor analysis

The loading factor performance modelling is an important part of centrifugal compressor performance calculation. The presented information on model stages’ test data confirms the fact that the loading factor versus flow coefficient at an impeller exit is a linear function independent of Mach number (subsonic flow). The test data and the design characteristics of the series of 10 model stages are compared with the calculation of an inviscid flow and with calculations done using the NUMECA software. Math models offered by the authors, and inviscid calculations solve the problem of a primary design. The CFD-calculation for final solution is non-satisfactory. If the loading factor is calculated by total temperature difference and flow coefficient is calculated by a continuity equation, the performance is not quite linear and lies much higher. For the considered stages CFD-calculation inaccuracy is + (0,06 … 0,12). CFD-calculated flow coefficient is inside 0,96 … 0,98 of the measured and of the calculated by the Math model

Verification of a simplified mathematical model of centrifugal compressor stages

To calculate the efficiency of a centrifugal compressor, it is sufficient to know the design parameters and similarity criteria: flow rate coefficient, loading factor, relative hub ratio, Mach number. The effect of the inlet nozzle and the diffuser type is also taken into account. The original simplified model was successfully used for calculation of compressors’ candidates in computer programs of the Universal Modelling Method. Recently, the model has undergone significant revision and been remade. The modernized model is used in the program for primary design of centrifugal compressors. The authors verified the new model, comparing the calculated efficiency with the measured efficiency of several dozens of model stages 21CV family and low flow rate model stages. In total, calculations were carried out for more than thirty model stages. The range of design parameters of analysed model stages is quite wide: flow rate coefficient 0.00564 – 0.0676; loading factor 0.384 – 0.742; hub ratio 0.258 – 0.466

The simulation of gas-dynamic characteristics of centrifugal compressors in turbo-expander units

Prof. Y. Galerkin and his team have developed and completed designs of 19 single-stage centrifugal compressors for turbo-expander packaged units applying Universal Modeling Method for the company “Turbokholod JSC” since 2005. The most powerful compressor is 6500 kW. The highest delivery pressure is 12 MPa. One hundred fifteen turbo-expander packaged units with total capacity 400 000 kW were manufactured, installed and were in operation in December 2018. The gas-dynamic characteristics of compressors comply with technical specification when operated within given range of initial temperatures and initial and final pressures up to 16 combinations for some compressors. The dimensionless characteristics of the compressor stages vary within the range of design parameters: flow rate coefficient 0.0278-0.0697, loading factor 0.43-0.71. The simulation of gas-dynamic characteristics of one of the designed compressors by the newest version of mathematical model is presented as an example, demonstrating the simulation features and effectiveness

HETEROSUBTYPIC IMMUNE RESPONSE AND CROSS-PROTECTION AGAINST A HIGHLY PATHOGENIC A (H5N1) INFLUENZA VIRUS IN MICE IMMUNIZED WITH COLD-ADAPTED A/LENINGRAD/134/17/57 (H2N2) INFLUENZA VIRUS

While investigating the efficacy of an H5N2 ca reassortant vaccine candidate in protecting against a lethal challenge with a highly pathogenic (HP) H5N1 virus in the mouse model, we observed a degree of cross-protection provided by the ca Len/17 (H2N2) virus itself. 80% of mice administered a high dose of attenuated Len/17 vaccine intranasally (i.n.) survived after a lethal challenge with A/Hong Kong/483/97 H5N1 virus. Therefore, we investigated the basis of the cross- reactive immunity between H2N2 and H5N1 viruses that may have contributed to recovery from lethal HK/ 483 virus infection. Sera from mice immunized i.n. with Len/17 did not cross-react with HK/483 virus in neutralization or hemagglutination-inhibition assays, however IgG and IgA antibodies that cross-reacted with the hemagglutinin and neuraminidase of H5N1 1997 viruses were detected. Spleen cells from mice immunized i.n. with Len/17 vaccine showed enhanced production of IL-2, IL-4, IL-5, IL-10, and IFNγ following in vitro stimulation with inactivated H5N1 virus. Our findings indicate that both cross-reactive humoral and cellular immunity induced by Len/17 H2N2 vaccine may plays a role in recovery from lethal H5N1 virus infection. A better understanding of the mechanisms of heterosubtypic immunity will improve vaccine design against HP avian influenza viruses

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

SYSTEMIC ANTIBODY AND CELLULAR IMMUNE RESPONSES IN INFLUENZA INFECTION AND POSTSVACCINATION

Abstract. Post-infection immunity represents an immunogenicity standard for antiviral vaccines, including those against influenza. To estimate the immunogenic properties of vaccine preparations, it is necessary to compare the quantitative and qualitative parameters of immune responses to the vaccine strain and the virulent virus from which it is prepared. However, for ethical reasons, such human studies are difficult, because there is the possibility of pathogenic viral infection.The aim of this experimental work was to compare systemic immune responses to the pathogenic mouse influenza virus A (H1N1), and an attenuated reassortant virus, genetic formula 2/6 (R 2/6), an experimental analogue to the live influenza vaccine.It was shown, that R 2/6 lagged behind the pathogenic parental virus (PPV) in activated induction of circulating IgG-antibodies, secretion of a marker Th1-cytokine IFN-γ by splenocytes, and CTL (CD8+) production in the spleen. On the other hand, R 2/6 was highly competitive with PPV, with regard to quantitative proliferative parameters of pooled splenocytes, stimulation of Th (CD4+) cells, B-cells (CD19+), and Th2-cytokine IL-2. IL-6 production in the spleen was poorly induced by both viruses.Thus, attenuation of influenza A (H1N1) virus by the 2/6 genetic reassortment differentially influences the induction of systemic immunity constituents. i.e., some parameters of immune response may be reduced, while others are not altered. When preparing vaccine strains for live influenza vaccines, an attention should be given first of all to increased induction of circulating antibodies that comprise the major components of antiviral immunity