Comparison of commercial ELISA test kits from Australia and the USA with the serum neutralization test in cell cultures for the detection of antibodies to the infectious laryngotracheitis virus of chickens

Abstract

The objective of this work was the evaluation under our conditions of two commercial ELISA kits for the detection of antibodies to avian infectious laryngotracheitis (ILT) virus, one from Australia (Trop-ELISA, TropBio) and one from the USA (ProFLOK-ELISA, KPL), and to compare their performance with the conventional serum neutralization test (SNT) in chick embryo liver cells. Repeatability varied considerably, particularly when using the Trop-ELISA. Therefore, if individual results are important, at least two parallel measurements per serum sample are recommended. In 89.3% of the sera tested by SNT, results of two parallel measurements did not vary by more than one 2-fold dilution step. There was good linear correlation between both ELISAs and the SNT, the correlation coef® cient for the Trop-ELISA being r 5 0.758 and for the ProFLOK-ELISA r 5 0.867. The negative/positive cut-off was rede® ned to suit our conditions. Sera with a SN titre of $ 1:4 were considered positive. Sera with # 15% absorption in the ProFLOK-ELISA were considered clearly negative. For the Trop-ELISA, extinctions of $ 0.477 were considered positive, # 0.168 clearly negative. Values in between were regarded as doubtful for young chickens and as possibly due to non-speci® c reactions in older chickens. The sensitivity and speci® city of the ELISAs relative to the SNT were 87 and 77% for the Trop-ELISA, and 95 and 60%, respectively, for the ProFLOK-ELISA. However, the results indicate that the sensitivity of the ELISA is higher than that of the SNT, because most sera showed similar deviations from SNT results with both ELISAs. Generally, both ELISAs were a suitable alternative to the SNT under our conditions, as long as only negative/positive results are required.

Survey of infectious laryngotracheitis outbreak in layer hens and differential diagnosis with other respiratory pathogens

“…Although Infectious laryngotracheitis virus (ILTV) strains are antigenically homogenous, ILTV strains naturally vary in virulence, from highly virulent strains, causing high morbidity and mortality, to strains with low virulence, which that produce mild-to-unapparent infection (Bauer et al, 1999;Guy & Bagust, 2003). Clinical signs associated with the severe form of the disease include gasping, depression, nasal discharge, conjunctivitis, and expectoration of bloody mucus.…”

RFLP analysis of recent Northern Ireland isolates of infectious laryngotracheitis virus: Comparison with vaccine virus and field isolates from England, Scotland and the Republic of Ireland

“…Although all strains of ILTV appear to be antigenically homogenous (Bauer et al, 1999), their virulence varies considerably, with the consequences of infection ranging from subclinical to severe respiratory disease and death (Bagust & Guy, 1997).…”

Glycoprotein-Based Enzyme-Linked Immunosorbent Assays for Serodiagnosis of Infectious Laryngotracheitis

“…The diagnostic potential of these ELISAs was assayed with sera collected from chickens vaccinated with various virus-vectored vaccines. Furthermore, the efficacy of our ELISAs was validated by testing field serum samples and compared to that of a commercially available ELISA as a reference (fowl laryngotracheitis virus antibody test kit; Zoetis, San Diego, CA) (15)(16)(17).…”