Outbreak of myelocytomatosis caused by mutational avian leukosis virus subgroup J in China, 2018

Abstract

Avian leukosis virus subgroup J (ALV‐J) was isolated in meat‐type breeder chickens for the first time in 1988 in the United Kingdom. Due to the application of an eradication program, there were fewer reports related to myelocytomatosis or ALV‐J in China after 2013. However, there was another breakout almost simultaneously in six provinces of China in February 2018. On‐site, 15‐ to 20‐week‐old broiler breeder chickens showed depression, paralysis and weight loss. Mortality for certain flocks reached 15%. Sick chickens showed numerous yellow–white neoplasms growing in the sternum, rib and lumbar vertebra and had hepatic and renal metastasis. Histopathological observation showed all neoplasms were myelocytomas, and there were massive myelocyte‐like tumour cells in the liver, kidney and bone marrow. To explore the aetiology of this re‐outbreak of myelocytomatosis in China, we collected tumour‐bearing chickens and isolated six strains of ALV‐J (GM0209‐1 to ‐6). Phylogenetic analysis of gp85 and gp37 showed GM0209 strains were clearly distinct from the prototype strain of ADOL‐7501, HPRS‐103 and NX0101, and there was a mutation, R176G, in the conserved region between hr1 and hr2 regions of gp85, which was not found in other 44 ALV‐J strains. The 3′UTR nucleotide sequences of GM0209 isolates showed there was a signature deletion of 11 nt that was also present in 3′UTR sequences of SCDY1 and NHH, two isolates that have a reported association with haemangioma, indicating this deletion could not determine the tumour type induced by ALV‐J. Although the eradication program of ALV‐J has been successfully applied in China, the outbreak of ALV‐J still occurred, and the virus strain spread quickly. Thus, the biocharacteristics and pathogenesis of mutational ALV‐J should be further studied.

Molecular characteristics of the re‐emerged avian leukosis virus in China, 2018–2019

“…Since early 2018, typical AL has re‐emerged in white‐feathered broilers in several provinces of China, and the daily mortality of those farms ranged with the mortality in affected farms ranging from 1/10,000 to 19/10,000 per day. Although a previous study has showed that in Shandong and Hebei, the outbreak of ALV was caused by a mutated strain of ALV‐J, mainly inducing myelocytomatosis in 15‐ to 20‐week‐old Ross broiler breeder chickens (Zhou et al, ), we noticed that there exist differences in pathogenic characteristics between different chicken farms, which drove us to conduct a wider epidemiological survey.…”

Rapid Detection of Avian Leukosis Virus Subgroup J by Cross-priming Amplification

“…ALV-J infection currently causes great economic losses in China [17], and it presence is associated with a variety of tumour types including myeloma, renal tumours and hemangioma [19,32]. The high incidence of tumours reduces production, and virus elimination increases production costs.…”

“…even spread to waterfowl and wild birds [16]. Most large foreign breeder companies had eradicated classic exogenous ALVs by the end of the 1980s, but ALV-J remains widespread in China [17].…”

The Distribution and Localization of Collagen Triple Helix Repeat Containing-1 in Naturally and Experimentally Avian Leukosis Virus Subgroup J-Infected Chickens

“…Attributed to the implementation of ALV-J eradication program (6), there were rarely reports of ALV-J or myelocytomatosis in China after 2013. Nevertheless, there were another intensive reports about ALV-J breakout almost simultaneously in six provinces of China in 2018, which attracted our attention (7). It is rather remarkable that there were extensive medullary-like tumor cells in the bone marrow, liver, and kidney, and all of the neoplasms were myelocytomas (7).…”