Polymun Scientific

Live-Attenuated Influenza Vaccine

Polymun has established a nasal spray vaccine employing live attenuated influenza strains we call Vero-Vac. It is produced with our proprietary, animal-component free cell culture technology using the Vero cell line. In addition, Influenza virus is an excellent carrier for foreign epitopes. At Polymun vaccine candidates were constructed for HIV and tuberculosis (TB).

The concept of attenuating influenza strains at low temperature was carried out using Vero cell culture instead of fertilized hen eggs. In serial passages of both influenza A and B viruses in Vero cells at 25°C several mutations were introduced leading to our donor or master strains. Subsequently, the vaccine strains are created by genetic reassortment of the two genes coding for the surface antigens hemagglutinin and neuraminidase from the contemporary wild type strain and all other genes from the cold adapted, attenuated proprietary master strain. Due to this composition, the vaccine strains acquire the attenuation with the temperature sensitive and cold adapted phenotype from the master strain, but at the same time display the antigenic properties of the contemporary pathogenic virus strain.The whole process of creating and producing the strains is done using the Vero cell line. This African green monkey kidney cell line has already been accepted for the production of other live and inactivated vaccines. Polymun has developed a completely defined, animal-component-free cultivation system, thus providing additional safety in combination with excellent economy. The use of a continuous primate cell line does not only improve safety and scalability of the production process, it also generates viruses that reflect their epidemic counterparts better than egg produced strains.The live attenuated influenza vaccine is administered intranasally as a spray thus mimicking the natural way of infection. A clinical trial comparing it to the successful Russian vaccine of the similar type (produced in fertilized hen eggs) was performed with encouraging results.In addition, a second generation of influenza vaccines was developed at Polymun. It is based on the attenuation of influenza viruses by engineering the non-structural (NS) gene. This approach creates a new type of live attenuated influenza vaccines and viral vectors. We demonstrated the possibility to modulate influenza virus pathogenicity by truncation of the NS1 protein in mice. Moreover, hyperattenuated and replication-deficient NS mutants used as intranasal vaccines showed the same protection against the virulent virus challenge in the same way as normally replicating vaccines. The truncated NS1 proteins stimulate the immune response by inducing the release of interferon, pro-inflammatory cytokines and chemokines.The NS gene technology not only can provide an interesting alternative to the current approaches for live influenza vaccines, they can also function as carrier of foreign antigens in the NS1 reading frame. For that purpose, Polymun has established functional techniques and selection systems (using the interferon deficient Vero cell line) to engineer and to introduce large foreign gene sequences into the NS1 gene of influenza. As a model we inserted a functional green fluorescence protein (GFP).