Avian leukosis/sarcoma retroviruses can infect chickens and cause various diseases, malignant tumor formations and mortality in infected chickens. The ALSV group of viruses consists of the endogenous virus of subgroup E which occurs in all chickens and does not cause disease but can interact with exogenous viruses of subgroup A,B,C, and D and cause disease in chickens. Avian leukosis viruses cause high economic losses in the poultry industry since infected chickens not only develop neoplasia but also have decreased production efficiency. Besides chicken to chicken horizontal transmission of ALSV viruses, infected chickens can pass the virus congenitally at a high frequency to the egg. To prevent transmission, the poultry industry must effectively identify infected hens and eggs, and remove them from the breeding populations. Current testing methods for ALSV identification are time consuming, lack sensitivity or specificity, or are ineffective in clearing ALSV infection from potentially infected chicken flocks. The objective of this investigation is to develop an RT-PCR detection system that could effectively screen for viral presence in chicken eggs. To achieve this goal, the aims of this research is as follows: (1) to develop a reverse transcription and polymerase chain reaction assay to detect avian leukosis/sarcoma retroviruses in egg albumen, (2) to perform a survey of the handling and storage conditions of commercial chicken eggs in retail stores in New Orleans, LA., and (3) to determine the molecular prevalence of avian leukosis virus in commercial chicken eggs using the RT-PCR detection system A RT-PCR detection system was developed to detect avian leukosis/sarcoma virus in egg albumen obtained from two strains of White Leghorn chickens naturally exposed to these viruses. A modified RNA isolation procedure using the Promega kit for RNA isolation was employed to isolate viral RNA from egg albumen extracted from eggs obtained from two commercial stocks of White Leghorn chickens. In the samples tested, compared to the 45% sensitivity of the IFA method which is commonly used in the poultry industry for ALSV detection, the RT-PCR technique has a sensitivity of 97% and a specificity of 100%. Sequence analyses confirmed avian leukosis viral presence in the RT-PCR generated product. The survey involving the handling and storage conditions of eggs in New Orleans retail store indicated that 75% of the retail stores hold eggs at a temperature compatible with ALSV survival in the eggs. In addition, 22% of participating retail stores reported using cracked eggs for preparing food for self or consumer use. The survey provided a sampling frame for conducting a study of avian leukosis/sarcoma virus prevalence in commercial chicken eggs. Based on a 20% estimate of avian leukosis viral prevalence, 240 eggs were randomly sampled from 20 retail stores in New Orleans, LA. RT-PCR analyses of the eggs indicate that there is at least a 14% prevalence of avian leukosis virus in commercial chicken eggs. In addition, 80% of the egg cartons in the New Orleans area contain an average of two eggs infected with ALV. Therefore, individuals consuming eggs are at risk of exposure to these poultry oncogenic retroviruses / acase@tulane.edu
| Identifer | oai:union.ndltd.org:TULANE/oai:http://digitallibrary.tulane.edu/:tulane_23297 |
| Date | January 1997 |
| Contributors | Pham, Thuy Diem (Author), Johnson, Eric S (Thesis advisor) |
| Publisher | Tulane University |
| Source Sets | Tulane University |
| Language | English |
| Detected Language | English |
| Rights | Access requires a license to the Dissertations and Theses (ProQuest) database., Copyright is in accordance with U.S. Copyright law |
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