Molecular and pathological study on Chicken Anemia Virus
Molecular and pathological study on Chicken Anemia Virus
Hanaa A. Elsamadony1, Laila A. Tantawy1, Sabry E. Omar2 and Heba A. Abd Alah1
ABSTRACT
Background: Chicken Anemia Virus (CAV) is an infectious disease that is causing major economic
losses in the poultry industry and these losses are attributed to high mortalities, reduced production and
cost for preventive medications.
Objective: The aim of this study was to identify CAV obtained from farms with problems associated
with decreased body weight and immunosuppression. Also to determine their relationship with vaccine
used in the field and other reference strains. Then to observe microscopic lesions and to detect CAV
antigens by immunohistochemically in thymus and bone marrow tissues of SPF chicks infected with
CAV.
Methods: In this study, 30 layer farms of age 40 to 100-days-old from different governorates
(Alexandria, Gharbia, Giza and Qalubia) were examined for CAV with real-time PCR and
histopathological examination. The positive samples were prepared and inoculated in SPF chicks' oneday-
old then at aged 10-days post-inoculation collected organs for PCR, sequencing and
immunohistochemically examination.
Results: There's one positive farm of age 100-days-old from Qalubia governorate. The
histopathological examination of positive sample showing severe depletion of hematopoietic cells in
bone marrow replaced by adipocytes. Spleen exhibited depletion of lymphocytes with focal
coagulative necrosis in addition to congested blood vessels. PCR was done on the positive real-time
PCR sample, which separate amplified band at 418 bp then the sequences was submitted to the
GenBank under accession number MH260568 for the VP1 gene. Our strain has 99% identity with
nucleotides of Indian and Japan strains, 97% amino acid identity with the same strains. Our circulating
strain has low nucleotides identity 37%, 38% and amino acid identity 15% for both with vaccinal
strains (Cux-1N/Germany and CAV/Nobilis®P4) respectively. The high percentage of similarity of
nucleotides identity with Egyptian isolates and our strain were with Egypt I/Giza 2009, Egypt
II/Fayoum I, Egypt III/Fayoum II that was 86% for all, as well as amino acid identity was 86%, 87%
and 86% respectively.
Conclusion: The obtained results indicate that our circulating strain has great differences from
vaccinal strains which used in the field, so we need periodic characterization of circulating CAVs in
Egypt to improve methods of virus control and to usually determine the relationship of circulating
CAV with vaccine strains and other CAV strains. The most obvious thing in this study, that’s we need
to make our vaccine from our strain which circulating in the field with periodic updating.
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January 2019
Vol. 5, Pages 1-141
