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Retrovirus-induced disease in poultry
1Institute for Animal Health, Compton, Newbury, Berks, United Kingdom.
Poultry Science
|August 26, 1998
Summary
Avian retroviruses like ALSV, REV, and LPDV cause significant poultry diseases. Understanding their oncogenes and transmission is key to controlling these economically impactful avian viruses.
Area of Science:
- Veterinary Virology
- Oncology
- Poultry Science
Background:
- Three main avian retroviruses cause poultry diseases: avian leukosis/sarcoma virus (ALSV), reticuloendotheliosis virus (REV), and lymphoproliferative disease virus (LPDV).
- ALSV classification includes slowly transforming (lacking oncogenes) and acutely transforming (possessing oncogenes) types, differing in disease onset and mechanism.
- Exogenous and endogenous viral strains exist, with exogenous viruses spreading via virions and endogenous via proviruses, both impacting commercial poultry traits.
Purpose of the Study:
- To elucidate the characteristics and disease-causing mechanisms of major avian retroviruses affecting poultry.
- To differentiate between slowly and acutely transforming avian leukosis/sarcoma viruses based on oncogene presence and disease progression.
- To outline the transmission routes (exogenous vs. endogenous) and control strategies for significant avian retroviral infections.
Main Methods:
- Classification of avian retroviruses based on oncogene presence (viral or cellular protooncogene activation).
- Analysis of viral envelope subgroups (A-E, J) for avian leukosis/sarcoma virus.
- Description of transmission mechanisms: vertical/horizontal via virions (exogenous) versus genetic transmission (endogenous).
Main Results:
- Slowly transforming ALSV induce late-onset leukoses by activating cellular protooncogenes; acutely transforming ALSV rapidly induce tumors using viral oncogenes.
- ALSV Subgroup J specifically targets myeloid leukosis, while Subgroup E viruses are typically endogenous.
- REV causes lymphomas in chickens and turkeys; an acutely transforming variant (Strain T) causes rapid disease. LPDV in turkeys causes lymphoproliferative disease of unknown etiology.
Conclusions:
- Avian retroviruses present diverse pathogenic mechanisms and transmission routes, significantly impacting poultry health and production.
- Control of exogenous avian retroviruses relies on eradication schemes, while endogenous viruses and REV lack widespread commercial control.
- Further research is needed to understand LPDV's nature and develop effective control strategies for all impactful avian retroviral diseases.