D I AGN OSTI C TESTI NG
TUESDAY 7 DECEMBER 2021
#ESWI VIRAL TIMES
CO N F E R E N C E N E W S PA P E R
PAN DE MI C THREATS FR O M THE AN I MAL WO R LD
Influenza as a zoonotic threat for future pandemics THE CURRENTLY ONGOING COVID-19 PANDEMIC HAS SHOWN US THAT POSSIBLE ZOONOTIC VIRUS SPILL-OVERS SHOULD CONCERN THE HUMAN POPULATION. ONLY A HUNDRED YEARS AFTER THE DEVASTATING SPANISH FLU, A CORONAVIRUS IS RESPONSIBLE FOR THE CURRENT PANDEMIC. HOWEVER, AVIAN INFLUENZA VIRUSES ARE STILL A THREAT FROM THE ANIMAL WORLD THAT MIGHT CAUSE A FUTURE PANDEMIC. Within domestic poultry, low pathogenic avian Influenza A (LPAI) virus subtypes H5 and H7 can evolve to high pathogenic avian influenza (HPAI) viruses which then show a systemic infection of the poultry with high virulence. The main difference between LPAI and HPAI is the cleavage site within the glycoprotein Hemagglutinin (HA). If humans are infected with the HPAI the case fatality rate can be very high. Lauren E Steele from the University of Queensland investigated, why LPAI evolve to HPAI in chicken but not ducks. She presented Neuropilin-1 as a possible new receptor for HPAI. As the LPAI HA might show a lower affinity to Neuropilin-1 compared to the HPAI HA, Neuropilin-1 could cause a positive pressure on the evolution of the HPAI. As Neuropilin-1 is expressed to higher levels in chicken endothelial cells compared to ducks endothelial cells this might contribute to the emergence of HPAI viruses in poultry but not in wild aquatic birds.
The transmission of HPAI from poultry to wild migrating birds poses a continuous threat to the global spread of HPAI viruses. Susanne Koethe from the FriedrichLöffler Institute presented data about the susceptibility of ducks to the HPAI H7N9 virus. She showed, that the infection of duck eggs with HPAI resulted in systemic infection of the embryo. Further, she demonstrated that even though ducklings infected with the HPAI showed only mild symptoms, the viruses could be transmitted to sentinel animals. Thus, HPAI H7 viruses anchor the risk of a global spread via wild migrating birds. Denys Muzyka from the Institute of Experimental and Clinical Veterinary medicine in Ukraine highlighted the importance of the surveillance of infected wild birds. He pointed out that Ukraine is a very unique region, where many migrating birds pass by and therefore constitutes a possible hotspot for viral transmission between wild birds. The detection of
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several LPAI H7 subtypes from clinically healthy ducks especially shows that close surveillance of wild birds is important for the early detection of Influenza viruses with zoonotic potential. El-Sayed Abdel-Whab from the FriedrichLöffler Institute demonstrated that not only the HA can determine the virulence of HPAI viruses. Indeed, he investigated two clades of HPAI H5N8 viruses and found, that the evolution of the more virulent Clade A favours shorter variants of the viral NS1 gene compared to the less virulent Clade B. He showed that a longer NS1 resulted in stunted virulence and transmissibility while shortening the NS1 gene in Clade B had no impact on the virulence. The session “Pandemic threats from the animal world” clearly underlined the importance of surveillance and analysis of avian influenza viruses as they might be the cause of the next pandemic.