الفهرس 
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Abstract
- This study was performed to conduct an epidemiological survey of H5N8 viruses recently spread in Egypt in commercial broiler farms with a questionnaire on the ability of some commercial vaccines available to protect against avian influenza H5N8 in Egypt.
- A field survey of 28 poultry farms was carried out during the period from June 2016 to May 2017. The trachea, lungs and liver samples were collected from birds with respiratory symptoms associated with high mortality rates with the change color of comb and leg to dark color similar to bird flu symptoms.
- Tissue of the trachea, lungs and liver was processed and 10% of the solution was performed. The solution was then injected into the fertilized egg embryos for 9 days. The eggs were observed daily for 5 days and the embryo was recorded during this period. Allantoic fluid was collected for the mixing test (HA) And then the real-time PCR test for H5 ,H9 influenza viruses , new castle and infectious bronchitis .
- Of the 28 samples tested, the results showed positive samples of influenza H5 only. There were 7 positive samples of Newcastle and one positive sample of influenza H9 while samples showed a common infection between H5 and Newcastle flu combined with H5 and H9 influenza together.
- The sequencing of the positive samples of H5 was sequenced and the sequence (PLREKRRRRGLF) was determined. This arrangement of amino acids indicates that these two avian influenza viruses are highly virulent (H5 N8) and the two genes were registered in the genbank)
Under the name Influenza A virus (A / chicken / Egypt / Alex-1/2017 (H5N8)
with.(Accession-number):MF182406
Influenza A virus (A / chicken / Egypt / Alex-2/2017 (H5N8)) with. Accession number: MF 182407
- Some commercial vaccines were then evaluated by artificial infection in 120 vaccinated poultry vaccinated with vector AI-HVT® ceva and Mefluvac vaccine (MSA) or Vector AI-HVT® ceva alone and isolating Influenza A virus (A / chicken / Egypt / Alex-2/2017 (H5N8).
- The chickens were divided into groups for the work of experimental infection in two different ages to conduct two separate experiments
In the first experiment, 60 chickens were divided into four groups of 15 birds / groups. The first group was vaccinated by Vector AI-HVT® ceva only. The second group was vaccinated with Vector AI-HVT® and Mefluvac vaccine. The other two groups were not vaccinated , The infection was at the age of 28 days.
,1ml of EID50 10 6 by distillation in the naso-occular route in the two immunized groups and in one unvaccinated group and another group not being immunized. In the weekly follow-up of the geometric mean of HI titer in birds at 28th day old, The first vector group Vector AI-HVT® ceva was close to the geometric mean of HI titer in the second group immunized by Vector AI-HVT® and Mefluvac vaccine® and the geometric mean of HI titer in the two groups vaccinated higher than those not vaccinated.
- Artificial infection in the two vaccinated groups leads to the emergence of some symptoms of avian influenza from swelling of the face and discoloration of the comb and leg and the birds huddled together with percent of mortality , but these symptoms were less severe than the symptoms that appeared on the group not vaccinated and the percent of mortality in the group( vector AI-HVT® vaccine )was only 50%. The second group (Vector AI-HVT® and Mefluvac vaccine®) was 60%, while the non-vaccinated group was 100% negative.
- Examination of histopathological changes showed that there was little impact in the tissues of the birds of the vaccinated groups, unlike the birds of the non- vaccinated group, which had a large destruction of cells from the virus.
- Tracheal and cloacal swab at the third day, fifth and seventh after the infection showed that the rate of shedding the virus in the birds of the second group (vaccinated vector AI-HVT® and Mefluvac vaccine ®) less than the birds of the first group (vaccinated vector AI - HVT® ceva). But the highest level of shedding was at the third group (un-vaccinated and challenged)
- The second experiment had the same performance of the first experiment and its group in terms of division of birds and the program of vaccination and evaluation of the reaction of these vaccines on birds, but the infection was at the age of 35 days the same dose used in the first experiment and the same virus.
In the weekly follow-up of the the geometric mean of HI titer in birds, the 35-day geometric mean of HI titer in the vector AI-HVT® ceva group was close to the the geometric mean of HI titer in the second group immunized by Vector AI-HVT® and Mefluvac vaccine ® and the geometric mean of HI titer in both vaccinated groups are higher than those that have not been vaccinated.
-It was clear that the least percent of mortality was recorded in group (Vector AI –HVT® and Mefluvac vaccine ®) by zero % and (Vector AI –HVT®only) by 20%. But the mortality % in non-vaccinated and challenged group was 100%.
-The weight loss in group (Vector AI –HVT® and Mefluvac vaccine®) is less than weight loss in group (Vector AI –HVT®)
-The histological effects of the virus at chicks were very rare at vaccinated groups but clear histological signs appeared at non-vaccinated birds.
-Tracheal and cloacael shedding of H5N8 HPAI in birds of different groups were detected at 3 ,5 and 7 days’ post infection.
-Tracheal and cloacael shedding of H5N8 HPAI in birds which vaccinated (Vector AI –HVT® and Mefluvac vaccine ®) was fewer than Tracheal and cloacael shedding of H5N8 HPAI in birds which vaccinated (Vector AI –HVT®) only. The highest shedding of the virus was at non-vaccinated and challenged group.
-Tracheal and cloacael shedding of H5N8 HPAI in birds at second experiment were fewer than the shedding at first experiment.
-This study shows the beginning of the spread of the H5N8 avian influenza virus in some provinces of the Republic that have been studied. So we have to be careful to prevent its spread. Moreover, we found the high rate of protection against experimental infection in vaccinated groups using Vector AI-HVT® which produces with the increase of bird age, we recommend using Vector AI-HVT® with breeder, layer, Municipal Chicks and sasso chicks. The role of the dead vaccine used in Mefluvac vaccine ® has also been shown to markedly reduce the rate of virus shedding well in both trials.
-The combination of vaccine loaded with Vector AI-HVT® with the dead vaccine Mefluvac vaccine ® is a good program with long-term with breeder, layer, native chicks and sasso chicks.