Newcastle Disease Antibody Test Card (Colloidal Gold Method)

Target and Hazard: Newcastle disease (ND) is caused by Newcastle disease virus (NDV, genus Avibulavirus, family Paramyxoviridae — avian paramyxovirus type 1). Chickens, turkeys, pigeons and many wild birds are susceptible; it is a Class II animal disease in China and a WOAH-notifiable disease. The virus is shed in respiratory and intestinal secretions and can spread over long distances by aerosols, contaminated feed and water, personnel and equipment, and poultry products. Infection with virulent strains causes respiratory distress, greenish watery diarrhoea and neurological signs such as torticollis; laying flocks show a sharp drop in egg production with soft-shelled eggs, and mortality is high, causing severe losses to poultry farms.

Significance of Testing: The card detects NDV antibodies in serum for on-site assessment of antibody levels and immune qualification after vaccination, helping to decide whether a booster is needed, to verify how well the vaccination programme is being implemented and to gauge maternally derived antibody levels in young birds. It is a rapid tool for immune monitoring on poultry farms; diagnosis of acute infection must rely on pathogen detection, and antibody testing cannot replace antigen confirmation.

Principle: Colloidal gold immunochromatographic assay in a competitive format: antibody in the sample competes with gold-labelled NDV antibody for the viral antigen coated on the test line (T); the higher the sample antibody level, the weaker the T line. An absent (or very faint) T line indicates a positive antibody result, while a clear T line indicates negative. Development of the control line (C) confirms test and procedure validity.

Performance and Applications: No equipment required; visual reading within 10–15 minutes; samples: serum or plasma (whole blood supported by some configurations); room-temperature storage and shipment for on-site use. Suitable for immune monitoring on breeding and commercial poultry farms and for rapid on-site screening at primary veterinary stations, poultry clinics and animal disease control institutions. Method: colloidal gold immunochromatographic assay (competitive format) | Samples: serum, plasma (whole blood supported by some configurations) | Time to result: 10–15 min | Reading: visual assessment of T/C lines — in this competitive format an absent or very faint T line indicates a positive antibody result, a clear T line indicates negative; C line is the procedural control | Format: tests/box (as stated on the label) | Storage: 2–30 °C, cool and dry; shelf life 24 months | Note: sensitivity, specificity, limit of detection, intra-/inter-assay CV and agreement with reference methods are subject to our internal QC report.