Comparative molecular study on Avian pox viruses
Comparative molecular study on Avian pox viruses
Sherif .M. Ibrahim*, Abd El-Razek. B. Abd El-Razek*. Hanan. M. El-Zahed Amal. A. Fatouh* and Ayatollah. I. Ibrahim*
ABSTRACT
The current study was conducted to determine the similarities and differences between vaccinal and isolated strains of Fowl pox virus (FPV) and Pigeon pox virus (PPV) based on biological and molecular basis. Vaccinal and isolated strains were propagated on the chorioallentioc membrane of specific pathogen free (SPF) embroynated chicken egg (ECE) showing the characteristic pock lesions for each strain with titers reached 4.5 and 3.5 log10 EID50/ml at 5th passage for FPV and PPV isolates, respectively. The isolated strains were further identified using the specific hyper-immune sera for each virus by virus neutrization test (VNT). As the Neutrization index (NI) for PPV and FPV isolates were 2 and 2.75 when neutrized by FPV hyperimmune sera (HIS) while it was 2.5 and 2 when neutrized by PPV (HIS). DNA was extracted from the produced pock lesions and polymerase chain reaction amplifying 578bp fragment of P4b gene and 1800 pb of fpv140 for FPV and PPV isolates and vaccine strains. Phylogenetic analysis for the amplified P4p product revealed close similarity of the FPV isolate (FPLH) and fowl pox vaccine (FPVV) with the published sequences for FPV in the Genebank. Unexpectedly, PPV isolates (PPLA, PPLR) and PPV vaccine (PPVV) showed high similarity to the published FPVs-P4b sequence in gene bank and distributed under genogroup A1 in the phylogenetic tree, while the PPV isolate (PPLH) was classified under genogrop A2 with high identity to published PPVs-P4b sequence in gene bank. This study recommend preparation of PPV vaccine from the circulating local PPV isolate, PPLH, which characterized through this study, after confirming its immune response as a candidate vaccine.
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