Preclinical evaluation of a replication-deficient intranasal DeltaNS1 H5N1 influenza vaccine.
BACKGROUND
We developed a novel intranasal influenza vaccine approach that is based on the construction of replication-deficient vaccine viruses that lack the entire NS1 gene (DeltaNS1 virus). We previously showed that these viruses undergo abortive replication in the respiratory tract of animals. The local release of type I interferons and other cytokines and chemokines in the upper respiratory tract may have a "self-adjuvant effect", in turn increasing vaccine immunogenicity. As a result, DeltaNS1 viruses elicit strong B- and T- cell mediated immune responses.


RESULTS
We applied this technology to the development of a pandemic H5N1 vaccine candidate. The vaccine virus was constructed by reverse genetics in Vero cells, as a 5:3 reassortant, encoding four proteins HA, NA, M1, and M2 of the A/Vietnam/1203/04 virus while the remaining genes were derived from IVR-116. The HA cleavage site was modified in a trypsin dependent manner, serving as the second attenuation factor in addition to the deleted NS1 gene. The vaccine candidate was able to grow in the Vero cells that were cultivated in a serum free medium to titers exceeding 8 log(10) TCID(50)/ml. The vaccine virus was replication deficient in interferon competent cells and did not lead to viral shedding in the vaccinated animals. The studies performed in three animal models confirmed the safety and immunogenicity of the vaccine. Intranasal immunization protected ferrets and mice from being infected with influenza H5 viruses of different clades. In a primate model (Macaca mulatta), one dose of vaccine delivered intranasally was sufficient for the induction of antibodies against homologous A/Vietnam/1203/04 and heterologous A/Indonesia/5/05 H5N1 strains.


CONCLUSIONS
Our findings show that intranasal immunization with the replication deficient H5N1 DeltaNS1 vaccine candidate is sufficient to induce a protective immune response against H5N1 viruses. This approach might be attractive as an alternative to conventional influenza vaccines. Clinical evaluation of DeltaNS1 pandemic and seasonal influenza vaccine candidates are currently in progress.
Romanova
Julia
J
Avir Green Hills Biotechnology AG, Vienna, Austria.
Krenn
Brigitte M
BM
Wolschek
Markus
M
Ferko
Boris
B
Romanovskaja-Romanko
Ekaterina
E
Morokutti
Alexander
A
Shurygina
Anna-Polina
AP
Nakowitsch
Sabine
S
Ruthsatz
Tanja
T
Kiefmann
Bettina
B
König
Ulrich
U
Bergmann
Michael
M
Sachet
Monika
M
Balasingam
Shobana
S
Mann
Alexander
A
Oxford
John
J
Slais
Martin
M
Kiselev
Oleg
O
Muster
Thomas
T
Egorov
Andrej
A
D000281:Administration, Intranasal; D000818:Animals; D001980:Bronchi / Q000166:cytology; D002460:Cell Line; D002645:Chickens; D002522:Chlorocebus aethiops; D004285:Dogs; D004353:Drug Evaluation, Preclinical; D004847:Epithelial Cells / Q000166:cytology; D005289:Ferrets; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000737:chemistry; D006801:Humans; D053124:Influenza A Virus, H5N1 Subtype / Q000235:genetics*; D007252:Influenza Vaccines / Q000378:metabolism / Q000627:therapeutic use*; D008264:Macrophages / Q000378:metabolism / Q000821:virology; D051379:Mice; D014709:Vero Cells; D014779:Virus Replication
D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007252:Influenza Vaccines