Avian orthoavulavirus 1, formerly known as avian paramyxovirus type-1 (APMV-1), infects more than 250 different species of birds. It causes a broad range of clinical diseases and results in devastating economic impact due to high morbidity and mortality in addition to trade restrictions. The ease of spread has allowed the virus to disseminate worldwide with subjective virulence, which depends on the virus strain and host species. The emergence of new virulent genotypes among global epizootics, including those from Egypt, illustrates the time-to-time genomic alterations that lead to simultaneous evolution of distinct APMV-1 genotypes at different geographic locations across the world. In Egypt, the Newcastle disease was firstly reported in 1947 and continued to occur, despite rigorous prophylactic vaccination, and remained a potential threat to commercial and backyard poultry production. Since 2005, many researchers have investigated the nature of APMV-1 in different outbreaks, as they found several APMV-1 genotypes circulating among various species. The unique intermingling of migratory, free-living, and domesticated birds besides the availability of frequently mobile wild birds in Egypt may facilitate the evolution power of APMV-1 in Egypt. Pigeons and waterfowls are of interest due to their inclusion in Egyptian poultry industry and their ability to spread the infection to other birds either by presence of different genotypes (as in pigeons) or by harboring a clinically silent disease (as in waterfowl). This review details (i) the genetic and pathobiologic features of APMV-1 infections in Egypt, (ii) the epidemiologic and evolutionary events in different avian species, and (iii) the vaccine applications and challenges in Egypt.

Fifty-one pigeon houses from both commercial lofts and backyard of different ages and breeds were investigated for incrimination of pigeon paramyxovirus-1 (PPMV-1) and/ or Newcastle Disease virus (NDV) during 2013-2015. The results of clinical examination revealed nervous signs (wing paralysis, head tremors, torticollis, opisthotonos and leg paralysis), greenish diarrhea, and respiratory signs, with variable mortalities. The gross lesions included congestion and hemorrhage in brain; nephrosis and/ or nephritis in kidneys, ulcer in intestine and mucoid enteritis. Virus isolation via chicken embryo inoculation revealed embryo congestion and hemagglutination (HA) activity of harvested allantoic fluids were detected 41 samples (80.39%) with HA titers ranging from 2 6 -2 10 . The hemagglutination inhibition (HI) results of the same isolates against PPMV-1 and NDV hyper immune sera which prepared in rabbits (1:5dilution) varied from 2 3 -2 10 in 38 virus isolates. The allantoic fluids of 41 haemaglutinating virus isolates were subjected to Reverse transcriptase polymeraze chain reaction (RT-PCR), Thirtyeight isolates evidenced successful products for partial amplification of fusion protein gene of NDV and PPMV-1 at 356 bp using specific primers. Restriction fragment length polymorphism (RFLP) using a set of three enzymes; HhaI, MspI and MboI. revealed that 9 strains (mesogenic / lentogenic PPMV-1), 27(mesogenic / lentogenic NDV), one velogenic strain for PPMV-1 and the other was NDV. MDT value in ECE revealed 72 ± 0.0 and 62.4±5.89 indicating that both isolates could be mesogenic. It could be concluded that both NDV and PPMV-1 are cocirculating among pigeons and causing economical losses. Rt-PCR followed by RFLP can be useful rapid tools for detection and identification of both viruses. Beside, in the view of the failure of adopted prophylactic vaccination, both LaSota and Inactivated PPMV-1 vaccines must be included to overcome the impact of aforementioned disease problems in pigeons.

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