Detection of Avian Leucosis Virus Subgroup J in Poultry Tissue Samples and Their Molecular Characterization
This study was carried out to diagnose and characterize avian leucosis virus subgroup J (ALV-J) specific sequence isolated from poultry organs with myelocytic infiltration. Archived tissues with and without myelocytic infiltration were examined by PCR followed by sequencing. Four ALV-J sequences...
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| Format: | Thesis |
| Language: | English |
| Published: |
2004
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/6573/1/FPV_004_1.pdf |
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| Summary: | This study was carried out to diagnose and characterize avian leucosis virus
subgroup J (ALV-J) specific sequence isolated from poultry organs with
myelocytic infiltration. Archived tissues with and without myelocytic infiltration
were examined by PCR followed by sequencing. Four ALV-J sequences
identified and named as; UPMIA6, UPMIAIO, UPMlA17 and UPMIA18 were
characterized based on sequence and phylogenetic analysis. Different
diagnostic tests (PCR, ELlSA and Virus isolation) for ALV-J were also
studied and compared. A total of 21 poultry tissue samples were examined
by PCR using primers (H5lH7) and 16 samples were found positive for ALVJ
proviral DNA. However, only 5 samples were found positive for ALV-J viral
RNA. Sequence analysis indicated that the 4 sequences have significant
homology ( >go%) when compared to A LV-J from U K a nd U SA. However,
based on phylogenetic analysis, the sequences of the ALV-J were close to
Houghton Poultry Research Station -103 (HPRS-103). In addition 3, 10, 3
and 8 amino acid substitutions were observed in sequences; UPMIAG,
UPMIAI 0, UPMIAI 7 and UPMIAI 8, respectively. All these substitutions were unique and have not been reported before from other ALV-J isolates.
The importance of these substitutions requires further study especially in
order to determine whether the sequences resemble variant ALV-J from UK
or USA.
Different diagnostic techniques were also compared for the detection of ALVJ
in a normal broiler breeder flock as the first isolation of ALV-J was made
from normal meat-type chickens. PCR was found to be more sensitive than
ELSA and virus isolation. However, even though the chickens were gp85
antibody positive, all the samples examined showed negative result for ALVJ
proviral DNA and virus isolation. In addition, no virus was isolated from
archived tissue samples with myelocytic infiltration. The actual explanation
for this finding is not clear, but several probable factors were presented and
discussed. In conclusion, ALV-J proviral DNA were detected in tissue
samples obtained from chickens with and without myelocytic infiltration.
However, no virus was isolated. The importance of PCR in detecting proviral
DNA and viral RNA from chickens with gp85 antibody requires careful
examination due to the complex nature of ALV-J infection. |
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