Recombinant IBV (B/YAMANASHI/4/2012) Hemagglutinin (a.a. 16-362) [His]

Influenza B virus (IBV) is considered a major human pathogen, responsible for seasonal epidemics of acute respiratory illness. Two antigenically distinct IBV hemagglutinin (HA) lineages cocirculate worldwide with little cross-reactivity. Live attenuated influenza virus (LAIV) vaccines have been shown to provide better cross-protective immune responses than inactivated vaccines by eliciting local mucosal immunity and systemic B cell- and T cell- mediated memory responses. We have shown previously that incorporation of temperature-sensitive (ts) mutations into the PB1 and PB2 subunits along with a modified HA epitope tag in the C terminus of PB1 resulted in influenza A viruses (IAV) that are safe and effective as modified live attenuated (att) virus vaccines (IAV att). We explored whether analogous mutations in the IBV polymerase subunits would result in a stable virus with an att phenotype. The PB1 subunit of the influenza B/Brisbane/60/2008 strain was used to incorporate ts mutations and a C-terminal HA tag. Such modifications resulted in a B/Bris att strain with ts characteristics in vitro and an att phenotype in vivo. Vaccination studies in mice showed that a single dose of the B/Bris att candidate stimulated sterilizing immunity against lethal homologous challenge and complete protection against heterologous challenge. These studies show the potential of an alternative LAIV platform for the development of IBV vaccines. IMPORTANCE A number of issues with regard to the effectiveness of the LAIV vaccine licensed in the United States (FluMist) have arisen over the past three seasons (2013-2014, 2014-2015, and 2015-2016). While the reasons for the limited robustness of the vaccine-elicited immune response remain controversial, this problem highlights the critical importance of continued investment in LAIV development and creates an opportunity to improve current strategies so as to develop more efficacious vaccines. Our laboratory has developed an alternative strategy, the incorporation of 2 amino acid mutations and a modified HA tag at the C terminus of PB1, which is sufficient to attenuate the IBV. As a LAIV, this novel vaccine provides complete protection against IBV strains. The availability of attenuated IAV and IBV backbones based on contemporary strains offers alternative platforms for the development of LAIVs that may overcome current limitations.

The present study was conducted to determine the antiviral activity of different Cholistani plants growing in the Cholistan Desert, Pakistan. Methanolic extracts of plants were prepared by dissolving air-dried, powdered plants in methanol and later concentrated in a rotary evaporator. The concentrated extracts were dissolved in distilled water and sterilized through filtration. To asses antiviral potential plant extracts were mixed with an equal concentration of a live virus and propagated for 7-11 days in embryonated eggs with appropriate controls. After 48 hours, the allantoic fluids were harvested and hemagglutination assay (HA) was performed for infectious bronchitis virus (IBV) and indirect hemagglutination assay (IHA) for infectious bursal disease virus (IBDV) to determine both virus titer, as well as evaluation of the inhibitory effects of various plant extracts. Almost all selected plant extracts exhibited an antiviral effect varying from plant to plant and manifested through controlling growth of IBV except Solanum surattense. The methanolic extracts of two plants Ochthochloa compressa and Sporobolos icolados, showed a 100% inhibitory effect demonstrated through no viral growth determined by HA assays. Similarly, other plant extracts also showed antiviral activity in the order of HA titer at 8 in case of three plants Haloxylon salicornicum, Neurada procumbens and Salsola baryosma, 16 for Achyranthes aspera, Haloxylon recurvum and Panicum antidotale. The HA values 32 and 64, respectively, for Oxystelma esculentum and Suaeda fruticosa were revealed. In case of anti-IBDV activity, the methanolic extracts of Achyranthes aspera, Haloxylon recurvum, Haloxylon salicornicum, Panicum antidotale, Salsola baryosma, Sporobolos icolados were shown to have the optimal antiviral potential (IHA titer 0). Similarly, extract of Neurada procumbens kept the IHA titer at 2 and Solanum surattense at 4. The extracts of Oxystelma esculentum and Ochthochloa compressa were least effective in controlling multiplication of IBDV and their IHA titer was equal to virus control. Overall, our studies open up new avenues in the development of much needed antivirals, utilizing indigenous resources. (C) 2016 PVJ. All rights reserved.