| Objective:Hepatitis B vaccination plays an important role in preventing hepatitis B,but at least 5-10% inoculated people cannot produce protective anti-HBs antibodies.Whether they are still susceptible to hepatitis B virus(HBV)is poorly understood.The study was conducted to observe the capacity of hepatitis B vaccine(HepB)non-responsive ducks to resist infection by duck hepatitis B virus(DHBV).Method:Eighty-two one-day-old sheldrakes found to be negative for HBV DNA by qualitative polymerase chain reaction(PCR)were used in this experiment.Sixty-five of them were randomly chosen and were inoculated with0.1 ml of HepB vaccine in the leg on days 2,9 and 16,while the remaining 17 ducks were intramuscularly injected with an equal volume of saline in the same location and on the same schedule(the blank group).Blood samples were withdrawn aseptically once a week for quantitative assessment of anti-HBs antibodies by ELISA since from the first vaccination dose for a period of four weeks.According to whether protective antibodies(anti-HBs)were produced after vaccination,the sheldrakes were divided into the responsive group(anti-HBs positive)and the non-responsive group(anti-HBs negative).Then,the three groups were injected intravenously with 0.2 ml of DHBV positive serum,followed by a four-week observation period.Blood samples were obtained before DHBV infection(T0)and after 28 days(T28).Serum DHBV DNA were detected by qualitative PCR and the viral load of DHBV DNA in positive serum was tested by fluorescent quantitative PCR(FQ-PCR)after DHBV infection(T28).Additionally,the OD values of serum DHBs Ag and DHBeAg and serum levels of AST and ALT were detected,and liver tissues were examined.Results: After DHBV infection,the infection(DHBV DNA positive)rate in the non-responsive group was 12.5%(2/16),closed to that of the responsive group with an infection rate of 18.75%(P=1.000);22obviously lower than the blank group which had an infection rate of 53.3%(8/15)(P=0.023).The DHBsAg positive rate in the non-responsive group was 18.75%(3/16),similar to the responsive group(25%,4/16)(P=1.000),and obviously lower than the blank group(60%,9/15)(P=0.029).The DHBeAg positive rates of the non-responsive group,responsive group and blank group were 18.75%(3/16),12.5%(2/16),and 26.7%(4/15)respectively.The groups were pair-wise compared by exact probabilities.There was no significant difference.The OD values of DHBs Ag and DHBeAg were increased in all three groups after DHBV infection.The increased DHBsAg OD values in the non-responsive group(0.14±0.41)were close to those of the responsive group(0.05±0.14)(P>0.05),while it was obviously lower than the blank group(1.35±1.70)(P<0.05).The increased DHBeAg OD values in the non-responsive group(0.04±0.10)were close to those of the responsive group(0.03±0.05)(P>0.05),and obviously lower than the blank group(0.33±0.77)(P<0.05).The differences in serum AST activity in the blank group,responsive group and non-responsive group were4.13±8.76,-0.56±3.7 and 1.63±4.46,respectively,and there were no obvious differences among the three groups(F=2.379,P>0.05).The differences in serum ALT activity in the blank group,responsive group and non-responsive group were 3.67±8.83,-2.38±5.58 and-1.48±10.69,respectively,and there were no obvious differences among the three groups(F=2.146,P>0.05).No obvious differences were observed among these three groups in terms of liver pathology.Conclusion:Hepatitis B vaccine non-responsive ducks can resist infection with DHBV to a certain extent.As with responsive ducks,liver function and liver histology were not protected(compared with blank group). |
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