No abstract

Raising backyard poultry under low biosecurity conditions is a common practice in Egypt. While vaccination is routinely applied in Egypt in commercial settings to curb the spread of avian influenza viruses, it remains less commonly used in backyard settings. We assessed the immunogenicity and protective efficacy of a H5N1 vaccine based on a contemporary Egyptian clade 2.2.1.2 virus among turkeys, ducks, geese, and chickens raised together in a backyard setting. Results showed that this vaccine elicits an immune response in all tested species reaching up to a hemagglutination inhibition titer of 10 log2 after a booster dose. However, this response varied between species. When challenged, vaccinated birds survived and shed less virus in comparison with unvaccinated birds. However, unvaccinated ducks showed no symptoms of infection and survived the duration of the experiment. Moreover, vaccinated ducks shed more virus as compared to vaccinated birds of other species. Hence, we recommend avoiding mixing various species in the backyards of Egypt. Our data indicates that vaccination can be effective in the backyard setting in Egypt, although planning should consider the species covered.

This study was conducted on 100 one-day-old broiler chicks to evaluate the effect of Poulvac E. coli vaccine in reduction of clinical signs and complications after concurrent infectious bronchitis virus (variant 02) and virulent E. coli O78 challenges. The birds were evaluated for clinical signs, mortality for 7 days post-infection, PM lesion score, average body weight and serological evaluation. Re-isolation and RT-PCR for the challenging infectious bronchitis virus (IBV) variant 02 were conducted thereafter. The results showed that the Poulvac E. coli at one-day old chicks in the presence of co-infection with virulent E. coli and IBV variant 02 provides better body weight gain at 35 days than the other groups. The challenge with IBV variant 02 alone in non-vaccinated birds doesn’t give any mortality; this indicated that the severity of IBV variant 02 increased by the presence of co-infection with Avian Pathogenic E. coli (APEc). The mortality percentage associated with both E. coli and IBV variant 02 infections in the none vaccinated group by Poulvac E. coli was 25% while this percentage was 10% of the vaccinated group. The Poulvac E. coli is not negatively affecting the immune response against different concurrent viral vaccines like Infectious bursal disease (IBD), and moreover, it improves the immune response against some others like Newcastle disease virus (NDV), Avian Influenza (AI) H5 and IBV.

The growth of the poultry industry in Nigeria is constrained by major poultry diseases, despite the implementation of vaccination programs. This study aimed to assess the level of protection against Newcastle disease (ND), infectious bursal disease (IBD), and avian infectious bronchitis (IB) afforded by current vaccination schedules and characterize the circulating virus strains in commercial poultry flocks in Nigeria. A cross-sectional study was conducted on 44 commercial poultry farms in Oyo and Kano states of Nigeria. Serum and tissue samples and data on flock, clinical and vaccination records were collected on each farm. Farms were classified as being protected or not protected against ND, IBD and IB based on a defined criterion. Real-time reverse transcription polymerase chain reaction (rRT-PCR) testing was performed for each target virus on tissue samples and positive samples were sequenced. A total of 15/44 (34.1%), 35/44 (79.5%), and 1/44 (2.3%) farms were considered to be protected against ND, IBD, and IB, respectively, at the time of sampling. NDV RNA was detected on 7/44 (15.9%) farms and sequences obtained from 3/7 farms were characterized as the lentogenic strain. Infectious bursal disease virus (IBDV) RNA was detected on 16/44 (36.4%) farms tested; very virulent (vv) IBDV and non-virulent (nv) IBDV strains were both detected in 3/16 (18.8%) positive samples. Sequences of IBDV isolates were either clustered with a group of genotype 3 virulent IBDV strains or were related to vaccine strains MB and D78 strains. IBV RNA was detected on 36/44 (81.8%) farms, with variant02, Massachusetts, 4/91, and Q1 variants detected. Sequences of IBV isolates were either clustered with the vaccines strains Massachusetts M41 and H120 or were most closely related to the D274-like strains or a clade of sequences reported in Nigeria and Niger in 2006 and 2007. This study revealed that most study farms in Oyo and Kano states did not have adequate protective antibody titers against IBV and NDV and were therefore at risk of field challenge. Infectious bursal disease virus and IBV RNA were detected on farms with a history of vaccination suggesting potential vaccination failure, or that the vaccine strains used mismatch with the circulating strains and are therefore not protective.

The use of molecular techniques for detection and characterization of the is very important for rapid and specific detection and characterization of the organism. During the period from 15th February, 2014 to 15th April, 2015, 425 nasopharyngeal swabs and 175 lung and spleen samples were collected and examined by conventional methods, 80 strains (18.82%) of were isolated from the calves, sheep and goat with respiratory manifestation. Meanwhile, 77 strains (44%) were isolated from emergency slaughtered animals. All the recovered strains were positive for specific PCR for detection of strains previously identified as by standard microbiological techniques. Multiplex PCR for molecular typing of the capsular antigens of the recovered revealed positive amplification of 1044 bp fragments specific to the capsular antigen type A with 105 strains (66.88%), and amplification 511 bp fragments of the capsular antigen type E with 52 strain (33.12%) and absence of B, D and F antigens. Multiplex PCR for molecular typing of the capsular antigens of can be used as a simple, sensitive, rapid, reliable technique instead of the serological techniques for identification of the capsular antigens of .