Strategy for Industrial Development of SPF Chickens in China

SPF chickens and chicken embryos are indispensable raw materials for high-level research in fidds of biology, medicine and veterinary science, and pro- duction and identification of a variety of biological products for people, livestock and poultry. The paper analyzes the current development status of SPF chickens in China and issues in industrial development, and puts forward suggestions for healthy development of SPF chickens in future.

Antibody Dynamic Changes in SPF Chickens and SPF Ducks Immuned with Recombinant Avian Influenza Virus H5 Subtype Bivalent Inactivated Vaccine

To study the immune effect of recombinant avian influenza virus H5 subtype bivalent inactivated vaccine （ HSN1, Re-6 strain ＋ Re-4 strain） and to provide the basis for formulating reasonable immune procedure of avian influenza vaccine in clinical practice. A total of 12 batches of vaccines from three companies were used for the iannune of SPF chickens and SPF ducks. Each chicken or duck serum was separately collected every 3 weeks until the immunization up to the 24^th week. The serum antibody titers of Re-6 and Re-4 were detected. The results showed that the HI titers of the inoculated SPF chickens and SPF ducks roached the peak when the immune time were the 6^th and 3^rd week after the first immunization respectively; then the titer decreased gradually as time prolonged; the highest titer of SPF chickens was greater than that of SPF ducks; the high titer duration of SPF chickens were longer than that of SPF ducks ; and all the vaccines from the three companies showed a good immune effect.

Isolation,Identification and Immunogenicity of a Chicken-derived Strain of Fowl Avidenovirus Type 4

In order to obtain a fowl avidenovirus type 4 strain with good immunogenicity,chicken liver tissues suspected of adenovirus infection in a chicken farm in Binzhou were treated and then inoculated to chicken liver hepatocellular carcinoma cells(LMH).The cell cultures were extracted for DNA,which was subjected to PCR identification and sequencing analysis,and animal regression test and immunogenicity test were also carried out.The results showed that one fowl avidenovirus strain was successfully isolated.The isolated strain was inoculated to LMH cells,and the first generation showed obvious cytopathic changes.The PCR identification result of the 8^(th)generation cell culture of the isolated virus strain on LMH cells was positive.The sequencing result and NCBI sequence alignment analysis showed that the isolated virus strain had the highest nucleotide similarity with fowl avidenovirus type 4,reaching 100%,indicating that the isolated strain was of fowl avidenovirus type 4.The strain could cause the death of 21-day-old SPF chickens,with a mortality rate of 100%,and could completely replicate the same symptoms as clinically infected chickens after being challenged.The three batches of oil vaccine prepared with the isolated strain had a protection rate of 100%,and the geometric mean values of serum agar expansion titers were 1∶4.6,1∶4.9,and 1∶4.6,respectively.It can be seen that the isolated virus is of fowl avidenovirus type 4 in group I,and has good immunogenicity.