Risk assessment of an influenza A virus H9N2 strain from Egyptian fruit bats

Alphainfluenza virus influenzae ( Influenza A viruses , FLUAV) of the subtype H9N2 are widespread in poultry farms and wild birds worldwide. The viruses have a broad host range and infect not only poultry but also various mammalian species. The viruses can be transmitted via the air, dust, feed, or water. Infection in birds is usually asymptomatic. However, infection increases the likelihood of a secondary bacterial infection, which is associated with a 10% mortality rate.

For individual tribes of the Subtype H9N2 was a transmission on farmed pigs and mink, with the animals displaying varying degrees of disease symptoms after infection. Various strains of the H9N2 subtype and their derivatives are also capable of infecting humans. However, infection in humans is usually accompanied by mild flu-like symptoms. Human-to-human transmission cannot be ruled out. According to the ZKBS recommendation on the "Risk assessment of influenza viruses as donor or recipient organisms for genetic engineering work according to Section 5 Para. 1 GenTSV" (Ref.: 6790-05-02-29, updated November 2015), the strains assessed so far FLUAV of subtype H9N2 the Risk group 2 assigned.

The strain A/bat/Egypt/381 OP/2017 was isolated in 2017 from swabs of a Egyptian fruit bat isolated, but did not show any symptoms of disease. Infection experiments later showed that A/bat/Egypt/381 OP/2017, unlike other H9N2 strains, is able to effectively and persistently infect the Ferrets to replicate. In contrast to previous infection experiments with other H9N2 strains, which caused a mild course of disease in the ferrets, 13% of the animals infected with A/bat/Egypt/381 OP/2017 lost weight and 93% of the animals developed high fever. However, none of the infected ferrets died. More recent studies have also shown that human ex vivo lung cultures can be infected with the strain A/bat/Egypt/381 OP/2017.

According to Section 5 Paragraph 1 GenTSV in conjunction with the criteria in Annex 1 GenTSV, the ZKBS classifies the Alpha influenza virus influenza Strain A/bat/Egypt/381 OP/2017 as a donor and recipient organism for genetic engineering work, as a precautionary measure Risk group 3 because this strain differs significantly in several pathogenicity aspects from other H9N2 strains that have previously occurred in mammals. Transmission of A/bat/Egypt/381 OP/2017 to humans and replication in human tissue cannot be ruled out. Pre-existing human immunity against A/bat/Egypt/381 OP/2017 is not to be expected. Therefore, with regard to the ZKBS statement Ref.: 6790-05-02-29 (updated November 2015), an increased pandemic risk from infection with A/bat/Egypt/381 OP/2017 cannot be ruled out at this time.

The complete ZKBS statement can be found at File number 45242.0216 can be retrieved.