DNA vaccines encoding the envelope protein of West Nile virus lineages 1 or 2 administered intramuscularly, via electroporation and with recombinant virus protein induce partial protection in large falcons (Falco spp.).
As West Nile virus (WNV) can cause lethal diseases in raptors, a vaccination prophylaxis of free-living and captive populations is desirable. In the absence of vaccines approved for birds, equine vaccines have been used in falcons, but full protection against WNV infection was not achieved. Therefore, two DNA vaccines encoding the ectodomain of the envelope protein of WNV lineages 1 and 2, respectively, were evaluated in 28 large falcons. Four different vaccination protocols were used, including electroporation and booster-injections of recombinant WNV domain III protein, before challenge with the live WNV lineage 1 strain NY99. Drug safety, plasmid shedding and antibody production were monitored during the vaccination period. Serological, virological, histological, immunohistochemical and molecular biological investigations were performed during the challenge trials. Antibody response following vaccination was low overall and lasted for a maximum of three weeks. Plasmid shedding was not detected at any time. Viremia, mortality and levels, but not duration, of oral virus shedding were reduced in all of the groups during the challenge trial compared to the non-vaccinated control group. Likewise, clinical scoring, levels of cloacal virus shedding and viral load in organs were significantly reduced in three vaccination groups. Histopathological findings associated with WNV infections (meningo-encephalitis, myocarditis, and arteritis) were present in all groups, but immunohistochemical detection of the viral antigen was reduced. In conclusion, the vaccines can be used safely in falcons to reduce mortality and clinical signs and to lower the risk of virus transmission due to decreased levels of virus shedding and viremia, but full protection was not achieved in all groups.
Clinic for Birds, Reptiles, Amphibians and Fish, Justus Liebig University Giessen, Frankfurter Str. 91-93, 35392, Giessen, Germany. dominik.fischer@vetmed.uni-giessen.de.
Dominik
D
Fischer
Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Novel and Emerging Infectious Diseases, Südufer 10, 17493, Greifswald-Insel Riems, Germany. joke.angenvoort@fli.bund.de.
Joke
J
Angenvoort
Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Novel and Emerging Infectious Diseases, Südufer 10, 17493, Greifswald-Insel Riems, Germany. ute.ziegler@fli.bund.de.
Ute
U
Ziegler
Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Novel and Emerging Infectious Diseases, Südufer 10, 17493, Greifswald-Insel Riems, Germany. christine.fast@fli.bund.de.
Christine
C
Fast
Clinic for Birds, Reptiles, Amphibians and Fish, Justus Liebig University Giessen, Frankfurter Str. 91-93, 35392, Giessen, Germany. kristina.maier@vetmed.uni-giessen.de.
Kristina
K
Maier
Fraunhofer Institute for Cell Therapy and Immunology, Perlickstraße 1, 04103, Leipzig, Germany. stefan.chabierski@izi.fraunhofer.de.
Stefan
S
Chabierski
Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Novel and Emerging Infectious Diseases, Südufer 10, 17493, Greifswald-Insel Riems, Germany. martin.eiden@fli.bund.de.
Martin
M
Eiden
Fraunhofer Institute for Cell Therapy and Immunology, Perlickstraße 1, 04103, Leipzig, Germany. sebastian.ulbert@izi.fraunhofer.de.
Sebastian
S
Ulbert
Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Novel and Emerging Infectious Diseases, Südufer 10, 17493, Greifswald-Insel Riems, Germany. martin.groschup@fli.bund.de.
Martin H
MH
Groschup
Clinic for Birds, Reptiles, Amphibians and Fish, Justus Liebig University Giessen, Frankfurter Str. 91-93, 35392, Giessen, Germany. michael.Lierz@vetmed.uni-giessen.de.
Michael
M
Lierz
D000818:Animals; D000914:Antibodies, Viral / Q000097:blood / Q000378:metabolism; D001715:Bird Diseases / Q000517:prevention & control* / Q000821:virology; D018274:Electroporation / Q000662:veterinary; D046093:Falconiformes; D007273:Injections, Intramuscular / Q000662:veterinary; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D019444:Vaccines, DNA / Q000494:pharmacology*; D014759:Viral Envelope Proteins / Q000235:genetics* / Q000378:metabolism; D014766:Viremia / Q000517:prevention & control / Q000662:veterinary / Q000821:virology; D017201:Virus Shedding; D014901:West Nile Fever / Q000517:prevention & control / Q000662:veterinary* / Q000821:virology; D053060:West Nile Virus Vaccines / Q000494:pharmacology*; D014902:West Nile virus / Q000276:immunology*
D000914:Antibodies, Viral; D011994:Recombinant Proteins; D019444:Vaccines, DNA; D014759:Viral Envelope Proteins; D053060:West Nile Virus Vaccines; C065696:glycoprotein E, Flavivirus