| Duck plague, or Duck virus enteritis (DVE), caused by duck enteritis virus (DEV), is an acute, contagious and lethal disease of waterfowl(ducks, geese, and swans) of the family Anatidae, which can cause substantial mortalities in both farmed and wild waterfowl. Due to its high morbility and mortality, DVE can cause great econmic losses, and is one of the major diseases impairing poultry production. The molecular characters of the duck enteritis virus are poorly elucidated due to a shortage of the sequence information of its genome. Thus, the fundamental research about virus gene function, virus infection and replication, also antiviral mechanism are severely limited. However, the virus vector vaccine based on duck enteritis virus show a promise future.Construction of genomic library is essential for the fundamental research of duck enteritis virus. In order to conctruct the genomic library, at first, high quality duck enteritis virus genomic DNA must be prepared and purified. After propagating in chicken embryo fibroblast,duck enteritis virus C-KCE strain was frozen and melt repeatedly and purified by differential velocity centrifugation and sucrose density gradient centrifugation subsequently. DNA preparation was conducted by follow the classical method(lysised by Proteinase K and SDS, followed by Phenol:Chloroform extraction and ethanol precipitation). The purified DEV genomic DNA was cut with 31 restriction enzyme and analysised on CHEF MAPPER. Results showed that and the whole DEV genome located between 145kb-194kb and the DNA sample was Highly purified and ready to be used for genomic library construction.In order to study the unknown region of DEV genome, we amplified two fragments, which located at UL and US region respectively, five ORFs which were homology to HSV were identified. UL41 gene encode viral host shut-off protein; UL42 encode DNA polymerase processivity factor; US7 and US8 gene encode membrane glycoprotein gI and gE. We also found that US1 gene has two copies in DEV genome.Duck enteritis virus is a remained ungrouped hepesvirus according to the report of Eighth International Committee on Taxonomy of Viruses (ICTV), lots of articles concernning about the taxonomy of DEV have published recently, there provide a large amount of proof, which based on Phylogenetic analysis of newly identified DEV genes, that Duck enteritis virus should be classified into the Alphaherpesvirinae subfamily in the family Herpesviridae. In our study we cloned four genes, UL41, UL42, US7 and US8. Phylogenetic analysis was conducted by using these genes among thirteen herpesviruses, the result showed that the duck enteritis virus itself branched and was most closely related to mardivirus, thus consistent with those reported previously.The use of live attenuated virus for the control of duck enteritis virus has achieved great success in the past several decades, it's safe and efficient, However, it has a disadvantage that the natural infected and vaccinated ducks can not be differentiated, as like other herpesvirus-induced diseases, DEV has acute and chronic forms, the survivors can persistently shed the virus into environment. Also some birds establish an asymptomatic carrier state after infection, which makes the monitor and control of the disease more complicated. It is obvious that duck enteritis virus can be engineered as a live virus vector for expression of exotic genes, considering the special ecology role that ducks played in the transmission of AIV, the recombinant duck enteritis virus that express HA gene of AIV show a prosperous future for new vaccine development. Thus, we constructed four transfer vector in presumed site(US2, US10, TK , UL45) that is nonessential for the invitro replication in order to construct the recombinant in the future.
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