Identification Of Avian Hepatitis E And It's Pathogenicity

Avian hepatitis-E-virus infection is a disease of broiler breeders and table-egg layers.Infections may be subclinical or associated with low mortality and mild decreases in egg production.The clinical disease caused by avian hepatitis E virus is referred to as hepatitis-splenomegaly(HS)syndrome(first recognised in Canada in 1991)and as big liver and spleen(BLS)disease(first recognised in Australia in 1980).From mid-1993 to 2001,a disease similar to HS syndrome occurred in Canada and the USA and was referred to as necrotic hemorrhagic hepatitis-splenomegaly syndrome,necrotic hemorrhagic hepatomegalic hepatitis,hepatitis-liver hemorrhage syndrome,or chronic fulminating cholangiohepatitis.In China,the prevalence of aHEV in avian livestock has been increasing,but the causative strain has not been known.Recently,we also have seen lesions in dead broiler chickens with lesions consistent with HS syndrome in China.In this Study,we analyzed serum samples from different chickens throughout Shandong to study the prevalence of aHEV antibodies.In addition,we collected bile samples from different chickens to identify the causative aHEV strain.1.Identification of aHEV in broiler chickensWe tested serum samples for aHEV antibodies by using an ELISA(BioChek,Reeuwijk,the Netherlands)essentially as described by the manufacturer.We used reverse transcription PCR to isolate the aHEV RNA genome from chicken bile,and 3 sets of degenerative primers were designed to amplify a specific region of the genome.Following the primer walking strategy,we designed sequencing primers and We then sequenced the amplified gene of the aHEV strain isolated from chickens in Shandong and compared the sequence of strain with complete or near-complete sequences in GenBank for other aHEVs that had been isolated from chickens;HE-1 shared 98.8%-100%sequence identity with the other aHEVs.2.Pathogenicity of the identified aHEV to broiler chickensUse liver and spleen grinding fluid containing AHEV virus attack 1 weeks of SPF chicken's wing vein to virus reproduction.Then use GE method for quantitative virus suspension.Using quantitative HE-1 strain suspension,through muscle injection respectively in three weeks,16 weeks putting poison ROSS 308 fathers generation of meat chicken,a total of 40.Poison attack every two weeks after collect serum and dead chicken.Autopsy liver and spleen,and at the same time observe the dead chickens the macroscopic damage of liver and spleen and its pathological changes,and recording the ratio of the liver,spleen,and weight.By means of the serum samples were collected for rt-pcr and dot hybridization detection,found the blank control group A 10 chickens to 28 weeks did not die,and the antibodies are negative(S/P<0.2),liver weight than the average 2.98%,spleen weight than the average 0.28%,virus disease were negative.Group B 10 chickens in only 3 weeks to poison,raising to 28 weeks 1 only death,poison attack in five weeks,7 weeks respectively after only 3 antibody positive(S/P in 0.2-0.25),chicken liver weight ratio is 3.36%,the death of spleen weight ratio is 0.36%,the death of chicken in 22 weeks and 24 weeks of viremia.Group C 10 chickens in 16 weeks of poison,only to 28 weeks killed nine cats,tapping the poison from the 20th week until after 28 weeks are antibody positive(S/P in 0.2-0.58),dead chicken liver weight than the average 7.11%,spleen weight than the average 1.4%,all chickens in from 18 week continued viremia.Group D10 chickens in 3 weeks,16 weeks twice against poison,raising to 28 weeks killed three,five weeks,7 weeks after 3 weeks poison attack respectively in 1 only,4 only antibody positive(S/P in 0.21-0.25),after 16 times Tuesday against poison,from the 18th week until 28 weeks are antibody positive(S/P in 0.2-0.97),dead chicken liver weight than the average 4.1%,spleen weight than the average of 0.74%,in 20 weeks,22 weeks and 24 weeks of sporadic virus disease,virus disease were negative after 24 weeks.Avian hepatitis e animal pathogenicity studies on experimental chicken antibodies and pathogenicity of Viremia,and symptom survey,early infected with HEV antibody has a protective effect on infection.3 weeks old for non-susceptible period,early to challenge the body to produce an immune response,when the body has again been HEV infection,have a protective effect.Pathogenesis of HEV have a certain time limit.Early general challenge is not likely to cause disease to death,16-18 weeks of age it is easy to cause the body to challenge disease deaths and apparent BLS symptoms.Antibody production cannot be completely ruled out blood,persistence of Viremia.Access to these data and theory Foundation for the analysis of avian pathogenic mechanism of HEV.