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Chicks possess maternally derived antibody (MDA) against pathogens and vaccines previously encountered by the dams. This passive immunity is important in early life, when the immune system is immature and unable to fight off infection. On the other hand, MDA can also affect the development of the immune system and interfere with vaccination against avian diseases such as Newcastle disease (ND) and avian influenza (AI). The effect of MDA is generally investigated by studying the progeny of vaccinated dams, which is time-consuming, poorly flexible and expensive. Moreover, the antibody titres obtained are not homogeneous. In this study, a model was developed to offer a faster, more reproducible and cheaper way to study passive immunity in specific pathogen free chickens by injection of a polyclonal serum into the egg yolk at embryonic day 14, combined with an intraperitoneal injection at day 1. A satisfactory model, with consistent, homogeneous antibody titres, as well as persistence close to natural passive immunity, could be obtained for ND virus. On the other hand, the application of this optimized protocol in an H5 AI context induced only a low artificial passive immunity compared with that described in the literature for the progeny of AI vaccinated dams. This artificial model should facilitate future studies regarding the effect of passive immunity on vaccine efficacy at a young age and its effect on immune system development.

The aim of this study was to investigate the frequency of the Newcastle disease virus (NDV) infection and its virulence in exotic cage birds over a limited area and time period. A set of 335 samples was collected from 24 different species of exotic unvaccinated cage birds kept in the zoological gardens and bird markets of the Tehran province of Iran during 1.5 years. Except for three pigeons, all of the sampled birds were healthy with no clinical signs of Newcastle disease. NDV was detected in three sick pigeons by haemagglutination assay (HA), haemagglutination inhibition (HI) and reverse transcription-polymerase chain reaction (RT-PCR) tests while two of them were identified as virulent types by RT-PCR. Although the remaining samples were negative by Newcastle-disease-specific HA and HI tests, 35 of them (10%) were identified as positive and 25 (72%) were determined as the velogenic type by RT-PCR test. Five PCR products were sequenced and all were confirmed as NDV but sequences were different from each other and from other sequences from Iran. In total, 14 species (58%) were infected and 10 species were uninfected with the velogenic type without showing any signs. Pigeons are very sensitive to NDV infection and play an important role in its epidemiology. In this study, the PCR test was found to be a more sensitive and powerful method than the HA and HI tests for detection of NDV reservoirs and carrier status in exotic birds. Also, the frequency of infection with the virulent type showed that the exotic birds should probably be considered one of the main causes of recurrent annual epidemics of Newcastle disease in endemic regions.

The extensive circulation of the H5N1 highly pathogenic avian influenza virus, and the human health threat that it poses, has raised concerns over the food safety implications of this virus infecting poultry. In addition, among the most important risk factors for the possible emergence of avian influenza in the European Union and the United States, the European and Food Safety Agency and the US Department of Agriculture's Animal and Plant Health Inspection Service, respectively, have identified legal and illegal importations of infected poultry commodities. The present paper reviews existing knowledge on the presence of viable avian influenza viruses in poultry commodities.

Avian influenza (AI) and Newcastle disease (ND) viruses are heat labile viruses, but exact parameters for heat inactivation at egg pasteurization temperatures have not been established. In this study we artificially infected four egg products with two AI (one low [LP] and one high pathogenicity [HP]) and three ND (two low and one highly virulent) viruses, and determined inactivation curves at 55, 57, 59, 61 and 63 degrees C. Based on D(t) values, the time to inactivation of the viruses was dependent on virus strain and egg product, and was directly related to virus titre, but inversely related to temperature. For all temperatures, the five viruses had the most rapid and complete inactivation in 10% salt yolk, while the most resistant to inactivation was HPAI virus in dried egg white. This study demonstrated that the LPAI and all ND viruses were inactivated in all egg products when treated using industry standard pasteurization protocols. By contrast, the HPAI virus was inactivated in liquid egg products but not in dried egg whites when using the low-temperature industry pasteurization protocol.