Evaluation of the protection induced by avian influenza vaccines containing a 1994 Mexican H5N2 LPAI seed strain against a 2008 Egyptian H5N1 HPAI virus belonging to clade 2.2.1 by means of serological and in vivo tests.
Since 2006 Egypt has been facing an extensive epidemic of H5N1 highly pathogenic avian influenza (HPAI) with a huge number of outbreaks both in rural and intensively reared poultry areas. The use of efficacious vaccines in this country has been, and still remains, essential for the control and possible eradication of HPAI. The present study was performed to establish whether the administration of inactivated vaccines containing an H5 virus belonging to a different lineage to the Eurasian H5N1 HPAI viruses guarantees protection from clinical signs, provides significant immune response and is able to achieve a reduction of viral shedding in the face of a challenge with a contemporary H5N1 virus isolated in Egypt. Despite the genetic and antigenic differences between the vaccine strain (H5N2/Mexico) and the challenge strain (H5N1/Egypt), confirmed by molecular and serological (haemagglutination inhibition) tests, it was established that the immune response induced by these conventional vaccines is sufficient to prevent infection in the majority of birds challenged with a contemporary H5N1 Egyptian strain. The data reported in this study also indicate that there may be a low degree of correlation between haemagglutination inhibition titres, clinical protection and reduction of shedding.
Terregino
Calogero
C
OIE/FAO and National Reference Laboratory for Avian Influenza and Newcastle Disease, Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Università 10, Legnaro, Padua, Italy. cterregino@izsvenezie.it
Toffan
Anna
A
Cilloni
Filippo
F
Monne
Isabella
I
Bertoli
Elena
E
Castellanos
Lilia
L
Amarin
Nadim
N
Mancin
Marzia
M
Capua
Ilaria
I
D000818:Animals; D000917:Antibody Formation; D002645:Chickens / Q000276:immunology / Q000821:virology; D004534:Egypt / Q000453:epidemiology; D053124:Influenza A Virus, H5N1 Subtype / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D053125:Influenza A Virus, H5N2 Subtype / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D005585:Influenza in Birds / Q000453:epidemiology* / Q000276:immunology*; D011200:Poultry / Q000276:immunology / Q000821:virology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013047:Specific Pathogen-Free Organisms; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000627:therapeutic use; D014765:Viral Vaccines / Q000008:administration & dosage / Q000627:therapeutic use; D017201:Virus Shedding / Q000276:immunology
D015164:Vaccines, Inactivated; D014765:Viral Vaccines