Determination of Newcastle Disease virus Antibodies in Vaccinated and in Visceral Velogenic Newcastle Disease-infected Psittacines Using the Immunocomb System

U. Bendheim , A. Naveh, R. Jefet, R. Haran, J. Krebs, and I. Samina

Koret School of Veterinary Medicine, Hebrew University, Jerusalem (Bendheim); Biogal Laboratories, Kibbutz Galed (Naveh); Jerusalem Poultry Disease Laboratory (Jefet); Bird Clinic, Tal Shachar (Haran); and Department for Vaccine Control, Kimron Veterinary Institute, Bet Dagan (Samina), Israel

Abstract

The Immunocomb (IC) test was used to detect Newcastle disease virus (NDV) antibody responses in naturally infected and vaccinated birds. Based on the results of this study, the IC test can be used to detect both natural exposure to NDV and to monitor NDV vaccination of naive birds.

Introduction

The Immunocomb (IC) ELISA system for Newcastle disease virus (NDV) antibody determination has been in use since 1987. In 1993, it was developed for use in psittacines. The system was tested after a field outbreak of NDV originating from imported parakeets that spread to three locations.

NDV Viral Antibody Studies

The following species were tested for NDV antibodies: Cockatiel (Nymphicus hollandicus), Budgerigar (Melopsittacus undulatus), Ring-neck Parakeet (Psittacula krameri), African Gray Parrot (Psittacus erithacus), Orange-winged Amazon Parrot (Amazona amazonica), Blue-fronted Amazon Parrot (Amazona aestiva), Bourke’s Parakeet (Neopsephotus bourkii), Port Lincoln Parakeet (Barnardius zonarius), and a Moluccan Cockatoo (Cacatua moluccensis). All were IC positive. Forty two psittacines from several other imports were all negative.

Vaccination and Challenge Studies

African Gray Parrots, Cockatiels, Bourke’s Parakeets, and Budgerigars were vaccinated intramuscularly with inactivated NDV vaccine (VH strain 10 EID50 per bird). Cockatiels and Budgerigars also were vaccinated with live lentogenic NDV vaccine (VH strain. 10 EID50 per bird) by eye drop. A group of each were revaccinated after two weeks with live or inactivated vaccine.

The Budgerigars were challenged eight weeks post-vaccination according to the protocol of the Israeli Veterinary Services Department of Vaccine Control with velogenic NDV (Herev Laet strain, 10 lethal dose per bird IM). Prior to vaccination all tested birds were IC negative and hemagglutination inhibition (HI) negative (mean titer of log performed with chicken erythrocytes = 0 and with psittacine erythrocytes = 0.7, with a range of 0 to 3) as presented in Table 1.

One month post-vaccination with inactivated vaccine, all African Gray Parrots (Table 2) and Cockatiels (Table 3) tested were IC positive.

In African Gray Parrots the HI titer was 5.6 with chicken erythrocytes and 6.6 with psittacine erythrocytes. Two months post-vaccination the HI titers were 6.7 with chicken erythrocytes and 9.0 with psittacine erythrocytes. Nevertheless, two months post -vaccination Budgerigars were still IC negative and had a mean HI titer of 0 with chicken erythrocytes and 0.8 with psittacine erythrocytes. Two weeks post challenge all budgerigar survivors were IC positive and mean HI were 6.0 with chicken erythrocytes and 7.1 with psittacine erythrocytes. Mortality was 74% in the vaccinated birds and 100% in the unvaccinated. All vaccinated contact infected birds survived with negative HI and IC.

Discussion

Based upon the conclusions of this study, routine screening for NDV in imported psittacine birds has been adopted by the Israel Veterinary Services via the Immunocomb method. Quarantine stations obtain samples from five birds per species in all shipments which are tested. It can be concluded that IC testing also can be applied as a diagnostic tool for monitoring NDV vaccinations in psittacines.

This Page Last Updated May 15, 1998

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