الفهرس 
coverOnly 14 pages are availabe for public view
 |  | from | 127 |  |  |
| | | from | 127 | | |
Abstract
Avian influenza viruses are important veterinary and human health pathogens all over the world. It is unusual in that it can cause a range of disease symptoms in poultry -#102;-#114;-#111;-#109; a subclinical infection to being highly virulent with 100% mortality. br So, the aim of the present work is: br 1. The isolation of local AIV isolates -#102;-#114;-#111;-#109; the infected flocks. br 2. The genetic and antigenic identification or sub-typing of the AIV isolates. br 3. Full characterization of the isolated AIV strains. br 4. Phylogenetic analysis of the isolated AIV viruses in comparison with the other AIV Egyptian strains. br 5. Comparative relatedness between the local AIV isolates and the vaccinal strains contained in the different AIV vaccines. br 6. The effect of the similarity between the circulating field AIV isolates and the vaccinal strains on the efficacy of those vaccines in protecting the chickens against infection with AI viruses. br -#102;-#114;-#111;-#109; this study, it was found that: br 1. The Serological survey of serum samples -#102;-#114;-#111;-#109; infected flocks showed positive antibody against standard H5 avian influenza virus. The cumulative rate of positive antibody in sera collected -#102;-#114;-#111;-#109; the infected flocks at years of 2006, 2007, 2008, 2009 and 2010 against H5 avian influenza virus were 100%, 96.7%, 95%, 100% and 93.3%, respectively. br 2. The isolated AI viruses cause embryo deaths as early as 24 - 48 hours post inoculation and all samples showing complete positive haemagglutination. br 3. All isolate groups -#102;-#114;-#111;-#109; 2006 to 2010 were serologically belonging to H5-AIV positive while they were ND and EDS negative. The results of HI test for 2006, 2007, 2008, 2009 and 2010 isolate groups with H5N1 antisera were 10, 9, 9, 8 and 10 log2 while, were 8, 7, 7, 6 and 7 log2 against H5N2 antisera, respectively. br 4. The HA titer for each AI group were 6, 7, 8, 7 and 7 for the 2006, 2007, 2008, 2009, 2010 AIV groups, respectively. br 5. The IVPI value of the AI groups ranged -#102;-#114;-#111;-#109; 2.1-2.5. So, all of them considered to be a highly pathogenic AIV for chicken. br 6. The AIV titer was expressed as EID50 and ranging -#102;-#114;-#111;-#109; 109-1010.1 for all AI isolate groups br 7. The results of RT-PCR test for M gene confirmed that all the isolates groups were AIV-type A positive. While, genetic identification of the AI isolates by RT-PCR using specific primers for H5N1 yielded a strong positive reaction. While RT-PCR using F gene primers proved that all the isolated viruses was ND negative. br 8. The phayelogenetic tree of the Egyptian AI isolates was: br • The AI isolates -#102;-#114;-#111;-#109; 2006 were identical with each other and fell into the Egyptian group B reference strains with about 100 % identity with them. br • The AI isolates -#102;-#114;-#111;-#109; between 2007-2009 were grouped together with Egyptian group E reference strains with about 98-99.5 % identity with them. br • The AI samples -#102;-#114;-#111;-#109; 2010 were identical with each other and showed the closest relation to the Egyptian group C reference strains with about 98 % identity with them. br • It was found that 2006 isolates were identical to the 2007, 2008, 2009 groups with 97.5 % and to 2010 group with 96.2 %. While, the degree of identity between 2010 isolates and 2007, 2008, 2009 was 94.5 %. br • The deduced amino acid sequence of HA gene of the 2007, 2008, 2009 AI isolates revealed substitutions of about 10 amino acids with 2006 strains and about 13 amino acids with the 2010 isolates br 9. Results of in vivo and in vitro studies for vaccines efficacy showed that: br • H5N1 strain: A / Goose / Guangdong / 1 / 96 was identical to the 2007, 2008, 2009 groups with 91.3-91.5 % and to 2006 group with 93.8 %. While, the degree of identity between 2010 isolates to H5N1 strain was 90.7 %. br • H5N1Egy/pr8-1 strain: A /chicken / Egypt /A-18-H / 09 was identical to the 2007, 2008, 2009 groups with 99.1-99.5 %. Mean while, the degree of identity between 2006 and 2010 isolates to H5N1Egy/pr8-1 strain was 97.3 % and 96 %, respectively. br • The degree of identity between H5N2 strain: A / Chicken / Mexico / 232 / 94 and 2006, (2007, 2008, 2009) and 2010 AI isolates groups were 78.7 %, 76.7-76.9 % and 77.9 %, respectively. br • By the challenge test, it found that the percentage of vaccine batches produced valid protection were 88.5%, 76.6%, 96.3% and 100% for mono-H5N2, combined H5N2, imported H5N1 and H5N1Egy/pr8-1, respectively.