AVIR Green Hills Biotechnology´s viral engineering technology allowed to construct deltaFLU, a live attenuated replication-defective influenza virus vaccine. deltaFLU is highly immunogenic while being safely attenuated.
deltaFLU is a live attenuated influenza virus with an optimal balance between attenuation and immunogenicity. It is generated by reverse genetics and is produced in mammalian cells. This allows fast and efficient generation and production of vaccine strains against influenza. deltaFLU is applied intranasally with a spray device.
Background
Compared to traditional, inactivated virus preparations currently dominating
the influenza vaccine market, live attenuated viruses induce longer-lasting
and more cross-protective immunity with significantly higher protection
rates. We believe that, due to significantly higher efficacy rates and
the ease and painlessness of intranasal administration, the live attenuated
approach is superior to the inactivated injectable flu vaccines currently
on the market. However, although the live attenuated viruses on the market
have a good safety record, shedding of the vaccine virus occurs and unexpected
complications in young children, the elderly and immuncompromised people
might arise from wide-spread use.
A strategy that eliminates limitations and complications is the construction of a vaccine virus which undergoes only abortive replication and, at the same time, is capable of inducing a strong immune response. This concept is the basis of our deltaFLU technology.
On that basis we have generated live attenuated replication defective viral vaccines and presented evidence that influenza A and B viruses based on the deltaFLU technology are highly attenuated in animals such as mice and ferrets, yet provide protection from challenge with wild-type viruses. The particular properties– apathogenicity due to abortive replication while being highly immunogenic– make deltaFLU attractive as a safe and effective vaccine against endemic and pandemic influenza.
Advantages
- The vaccine is applied by the intranasal route. We believe
that, due to significantly higher efficacy rates and the ease and painlessness
of intranasal administration, the live attenuated approach is superior
to the inactivated injectable flu vaccines currently on the market.
Such live attenuated viruses also induce a longer-lasting and more cross-protective
immunity.
- The vaccine is replication-defective. Although deltaFLU
is a live attenuated vaccine, no viral shedding upon immunization occurs.
All data so far suggest that this vaccine is safe.
Therefore, even in the case of wide-spread use, unexpected complications
in young children, the elderly and immuncompromised people are unlikely.
- The vaccine is made by reverse genetics. This method
is essential for attenuation of highly virulent avian influenza viruses
and the timely distribution of candidate viruses in the case of a pandemic
emergency.
- The vaccine is produced in tissue culture. This is efficient,
fast and does not rely on the supply of eggs as used in traditional
methods. Thus, the process can be scaled up to fulfill logistic needs
during a pandemic infection. Moreover, since highly virulent avian strains
kill fertilized chicken eggs, the use of cultured cells for attenuation
and production is essential.
The deltaFLU project
is co-funded by the European Union. 
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