Molecular identification and virological characteristics of highly pathogenic avian influenza A/H5N5 virus in wild birds in Egypt.

Multiple incursions of different subtypes of highly pathogenic avian influenza (HPAI) A/H5NX viruses have caused widely considerable outbreaks in poultry and hundreds of human infections. Extensive reassortment events associated with currently circulating clade 2.3.4.4b of A/H5NX viruses have been widely recorded. Wild migratory birds contribute to the spillover of diverse viruses throughout their migration flyways. During our active surveillance of avian influenza in Egypt, we successfully isolated and fully characterized HPAI A/H5N5 virus of clade 2.3.4.4b that was detected in a healthy purple heron. The Egyptian H5N5 virus is genotypically similar with the same subtype that was detected in the far east of Russia and several European countries. The antigenic analysis showed that the Egyptian H5N5 virus is distinct from HPAI A(H5N8) viruses in Egypt. The virus preferentially binds to avian-like receptors rather than human-like receptors. Our results showed that the virus caused 100% and 60% lethality in chicken and mice respectively. Increasing active surveillance efforts, monitoring the dynamics of emerging AIVs, and risk assessment implementation should be globally applied especially in hot spot regions like Egypt.

Comparative Virological and Pathogenic Characteristics of Avian Influenza H5N8 Viruses Detected in Wild Birds and Domestic Poultry in Egypt during the Winter of 2016/2017.

The surveillance and virological characterization of H5N8 avian influenza viruses are important in order to assess their zoonotic potential. The genetic analyses of the Egyptian H5N8 viruses isolated through active surveillance in wild birds and domestic poultry in the winter of 2016/2017 showed multiple introductions of reassortant viruses. In this study, we investigated and compared the growth kinetics, infectivity, and pathogenicity of the three reassortant forms of H5N8 viruses detected in wild birds and domestic poultry in Egypt during the first introduction wave in the winter of 2016/2017. Three representative H5N8 viruses (abbreviated as 813, 871, and 13666) were selected. The 871/H5N8 virus showed enhanced growth properties in vitro in Madin Darby canine kidney (MDCK) and A549 cells. Interestingly, all viruses replicated well in mice without prior adaptation. Infected C57BL/6 mice showed 20% mortality for 813/H5N8 and 60% mortality for 871/H5N8 and 13666/H5N8, which could be attributed to the genetic differences among the viruses. Studies on the pathogenicity in experimentally infected ducks revealed a range of pathogenic effects, with mortality rate ranging from 0% for 813/H5N8 and 13666/H5N8 to 28% for 871/H5N8. No significant differences were observed among the three compared viruses in infected chickens. Overall, different H5N8 viruses had variable biological characteristics, indicating a continuous need for surveillance and virus characterization efforts.

Co-infection with different serotypes of FMDV in vaccinated cattle in Southern Egypt.

During 2015-2016 period, an outbreak of foot-and-mouth disease virus (FMDV) was observed in cattle in four governorates of the upper of Egypt. The infection was extended to the vaccinated cattle. A total of 54 mouth swabs and serum samples were collected from vaccinated cattle for serological and virological investigation. The typical clinical signs of FMDV infection were observed in all cattle under investigation. All samples were positive for FMDV using molecular methods, while the serological method showed 85% positive of tested samples. Typing of FMDV-positive samples using serotype-specific primers showed that 51.8% of samples were serotype O, 9.2% were serotype A, and 18.5% were SAT 2. Surprisingly, co-infections of serotypes A/SAT 2 (12.9%) and O/SAT 2 (7.4%) were also detected. By geographical location, the 3 serotypes A, O, and SAT2 were detected in all four governorates. The phylogenetic assessment of the detected viruses showed that two distinct groups of FMDV serotype O of East Africa-3 (EA-3) topotype were most closely related to circulating viruses in Sudan, as well as FMDV strains belonging to the topotype VII of serotype SAT 2. The detected SAT 2 strains clustered in separate clades in topotype VII, indicating new incursions. The VP1 signatures and protein sequences of some characterized viruses were analyzed. Multiple mutations were detected in VP1. Therefore, to enhance the control of FMD in Egypt, we recommend establishing an active surveillance system to characterize newly emerging virus strains/serotypes and subsequently updating vaccine strains.

Avian influenza H5N1 vaccination efficacy in Egyptian backyard poultry.

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.