Current Epidemiology and Co-Infections of Avian Immunosuppressive and Neoplastic Diseases in Chicken Flocks in Central China

Abstract

The avian immunosuppressive and neoplastic diseases caused by Marek’s disease virus (MDV), avian leucosis virus (ALV), and reticuloendotheliosis virus (REV) are seriously harmful to the global poultry industry. In recent years, particularly in 2020–2022, outbreaks of such diseases in chicken flocks frequently occurred in China. Herein, we collected live diseased birds from 30 poultry farms, out of 42 farms with tumour-bearing chicken flocks distributed in central China, to investigate the current epidemiology and co-infections of these viruses. The results showed that in individual diseased birds, the positive infection rates of MDV, ALV, and REV were 69.5% (203/292), 14.4% (42/292), and 4.7% (13/277), respectively, while for the flocks, the positive infection rates were 96.7% (29/30), 36.7% (11/30), and 20% (6/30), respectively. For chicken flocks, monoinfection of MDV, ALV, or REV was 53.3% (16/30), 3.3% (1/30), and 0% (0/30), respectively, but a total of 43.3% (13/30) co-infections was observed, which includes 23.3% (7/30) of MDV+ALV, 10.0% (3/30) of MDV+REV, and 10.0% (3/30) of MDV+ALV+REV co-infections. Interestingly, no ALV+REV co-infection or REV monoinfection was observed in the selected poultry farms. Our data indicate that the prevalence of virulent MDV strains, partially accompanied with ALV and/or REV co-infections, is the main reason for current outbreaks of avian neoplastic diseases in central China, providing an important reference for the future control of disease.

Immunoinformatics, molecular docking and dynamics simulation approaches unveil a multi epitope-based potent peptide vaccine candidate against avian leukosis virus

“…The most common avian retrovirus that causes a variety of neoplastic diseases in chicken is the avian leukosis virus (ALV) 2 . Globally, the ALV morbidity and mortality rates contributed to the poultry industry’s economic decline 1 , 3 . This is accompanied by subsequent adverse effects on the food supply worldwide.…”

“…Avian leukosis virus (ALV) is one of the most prevalent retroviruses causing neoplasms in chickens 1 , 2 . ALV related to the genus Alpharetrovirus and subfamily Orthoretrovirinae 3 . ALVs were shown causing avian leukemia/sarcoma in birds with major economic losses in the global poultry industry 1 , 4 .…”

“…ALV causes high morbidity rates than mortality rates In the infected flocks which negatively impacts hatchability and egg productivity 5 – 7 . In addition to the neoplasia, other factors contributed to mortality, including delayed maturation and diminished fertility rate, which have serious economic implications 4 .The co-infections of the virulent ALV isolates with reticuloendotheliosis virus (REV) and marek’s disease virus (MDV) are the main factor for prevalence of avian neoplastic diseases in China that hampering the future control of disease 3 . Therefore the affected flocks showed lower egg production and hemorrhages in the skin surrounding the feather follicles and phalanges 8 , 9 .…”

A Multiplex Quantitative Polymerase Chain Reaction for the Rapid Differential Detection of Subgroups A, B, J, and K Avian Leukosis Viruses

“…Coinfection, which can be more pathogenic and cause greater economic losses, is now prevalent in the poultry industry [ 16 , 17 ]. Due to its severe immunosuppressive effects, ALV often coinfects with other viruses such as MDV, REV, and IBDV [ 18 , 19 , 20 , 21 ]. Mixed infections can also occur between different subgroups of ALV.…”

Immunopotentiating effect of lentinan on chicks and its inhibitory effect on Marek's disease virus infection

“…Vaccine immunization is the most effective means of controlling MDV infection ( Nair, 2004 ). However, mixed infections with immunosuppressive viruses such as chicken infectious anemia virus ( CIAV ) and reticuloendotheliosis virus ( REV ) often lead to vaccine immunization failure ( Zhang et al, 2017 ; Li et al, 2021 ; Zheng et al, 2022 ). In addition, reports of some strains breaking through existing vaccine protection systems are gradually increasing ( Li et al, 2022 ; Liu et al, 2023 ).…”