Recombinant influenza virus vectors

A replication-incompetent influenza virus bearing the HN glycoprotein of human parainfluenza virus as a bivalent vaccine

Influenza virus and human parainfluenza virus (HPIV) are major etiologic agents of acute respiratory illness in young children. Inactivated and live attenuated influenza vaccines are approved in several countries, yet no vaccine is licensed for HPIV. We previously showed that a replication-incompetent PB2-knockout (PB2-KO) virus that possesses a reporter gene in the coding region of the PB2 segment can serve as a platform for a bivalent vaccine. To develop a bivalent vaccine against influenza and parainfluenza virus, here, we generated a PB2-KO virus possessing the hemagglutinin-neuraminidase (HN) glycoprotein of HPIV type 3 (HPIV3), a major surface antigen of HPIV, in its PB2 segment. We confirmed that this virus replicated only in PB2-expressing cells and expressed HN. We then examined the efficacy of this virus as a bivalent vaccine in a hamster model. High levels of virus-specific IgG antibodies in sera and IgA, IgG, and IgM antibodies in bronchoalveolar lavage fluids against both influenza virus and HPIV3 were detected from hamsters immunized with this virus. The neutralizing capability of these serum antibodies was also confirmed. Moreover, the immunized hamsters were completely protected from virus challenge with influenza virus or HPIV3. These results indicate that PB2-KO virus expressing the HN of HPIV3 has the potential to be a novel bivalent vaccine against influenza and human parainfluenza viruses.

Influenza viruses with rearranged genomes as live-attenuated vaccines

H5N1 and H9N2 avian influenza virus subtypes top the World Health Organization's list for the greatest pandemic potential. Inactivated H5N1 vaccines induce limited immune responses and, in the case of live-attenuated influenza virus vaccines (LAIV), there are safety concerns regarding the possibility of reassortment between the H5 gene segment and circulating influenza viruses. In order to overcome these drawbacks, we rearranged the genome of an avian H9N2 influenza virus and expressed the entire H5 hemagglutinin open reading frame (ORF) from the segment 8 viral RNA. These vectors had reduced polymerase activities as well as viral replication in vitro and excellent safety profiles in vivo. Immunization with the dual H9-H5 influenza virus resulted in protection against lethal H5N1 challenge in mice and ferrets, and also against a potentially pandemic H9 virus. Our studies demonstrate that rearranging the influenza virus genome has great potential for the development of improved vaccines against influenza virus as well as other pathogens.

The immunological potency and therapeutic potential of a prototype dual vaccine against influenza and Alzheimer's disease

Background

Numerous pre-clinical studies and clinical trials demonstrated that induction of antibodies to the β-amyloid peptide of 42 residues (Aβ₄₂) elicits therapeutic effects in Alzheimer's disease (AD). However, an active vaccination strategy based on full length Aβ₄₂ is currently hampered by elicitation of T cell pathological autoreactivity. We attempt to improve vaccine efficacy by creating a novel chimeric flu vaccine expressing the small immunodominant B cell epitope of Aβ₄₂. We hypothesized that in elderly people with pre-existing memory Th cells specific to influenza this dual vaccine will simultaneously boost anti-influenza immunity and induce production of therapeutically active anti-Aβ antibodies.

Methods

Plasmid-based reverse genetics system was used for the rescue of recombinant influenza virus containing immunodominant B cell epitopes of Aβ₄₂ (Aβ_1-7/10).

Results

Two chimeric flu viruses expressing either 7 or 10 aa of Aβ₄₂ (flu-Aβ_1-7 or flu-Aβ_1-10) were generated and tested in mice as conventional inactivated vaccines. We demonstrated that this dual vaccine induced therapeutically potent anti-Aβ antibodies and anti-influenza antibodies in mice.

Conclusion

We suggest that this strategy might be beneficial for treatment of AD patients as well as for prevention of development of AD pathology in pre-symptomatic individuals while concurrently boosting immunity against influenza.

Establishment of a chimeric, replication-deficient influenza A virus vector by modulation of splicing efficiency

Segment 8 of the influenza A virus codes for two proteins (NS1 and NS2/NEP) via splicing. Here, we developed a viral vector expressing a cytokine or chemokine instead of the interferon antagonist NS1. To achieve both the desired genetic stability and high transgene expression levels, NS2/NEP mRNA splicing efficacy had to be fine-tuned by modification of splicing elements. Expression levels of secreted foreign proteins could be further enhanced by fusing the N-terminal 13 amino acids of NS1 with an IgK-derived secretion signal peptide. Thus, the first start codon was used for translation initiation of both NS2/NEP and the foreign protein.