Abstract |
An ostrich farm of 929 birds that tested polymerase chain reaction-positive for highly pathogenic avian influenza H5N2 in a single sample was designated for culling, despite no evidence of sero-conversion as assessed by haemagglutination inhibition (HI) tests. A month later and immediately prior to culling, all birds were bled and tested with an IDEXX avian influenza virus (AIV) nucleoprotein (NP)-specific enzyme-linked immunosorbent assay (ELISA) and a high sero-prevalence was detected. To address the question of whether the NP-specific antibodies detected indicated exposure to H5 or non-H5 subtypes (H6N2 and H1N2 strains were also circulating regionally at the time), we developed two H5-specific ELISAs, both based on a recombinant H5 HA1 antigen. The H5 indirect ELISA used a horseradish peroxidase ostrich IgY conjugate that we produced in chicken eggs. The single-chain variable fragment (scFv) competitive ELISA (H5 scFv cELISA) used a scFv derived from an H5-immune chicken scFv library. By comparing IDEXX AIV ELISA results with those of the two H5-specific ELISAs and HI tests, we determined that up to 89% of the flock had been exposed to H5N2 AIV. We also detected evidence of suspected vaccination, since 17% of sera contained antibodies against the H5 glycoprotein but not the NP protein. Comparative analytical sensitivity indicated that HI tests are likely to miss up to 35% of H5-positive samples, and thus we consider that H5/H7-specific ELISAs should replace HI tests for ostrich testing in future.
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Authors | Celia Abolnik, Jeanni Fehrsen, Adriaan Olivier, Wouter van Wyngaardt, Geoffrey Fosgate, Charlotte Ellis |
Journal | Avian pathology : journal of the W.V.P.A
(Avian Pathol)
Vol. 42
Issue 3
Pg. 206-14
( 2013)
ISSN: 1465-3338 [Electronic] England |
PMID | 23607480
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Hemagglutinin Glycoproteins, Influenza Virus
- hemagglutinin, avian influenza A virus
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Topics |
- Animals
- Enzyme-Linked Immunosorbent Assay
(methods, veterinary)
- Hemagglutination Tests
(veterinary)
- Hemagglutinin Glycoproteins, Influenza Virus
(genetics)
- Influenza A Virus, H5N2 Subtype
(genetics)
- Influenza in Birds
(epidemiology, virology)
- Sensitivity and Specificity
- Seroepidemiologic Studies
- South Africa
- Struthioniformes
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