Will Taiwan's new avian flu strain infect humans? Bureau of Animal and Plant Health Inspection and Quarantine should promptly release the 8 gene segments to resolve doubts

Avian influenza is the abbreviated term for influenza in poultry. It is an RNA virus containing 8 gene segments. According to the H antigen and N antigen on the virus surface, it is divided into many subtypes. There are currently 16 kinds of H antigens and 9 kinds of N antigens. The two antigens combine to form various different subtypes, and can form as many as 144 subtypes (9×16). For example, H5N1 and H5N2 are different subtypes.

Avian influenza viruses readily reassort and mutate. To determine the source of a given avian influenza virus strain, it is necessary to analyze the 8 gene segments inside the virus and compare them on GenBank (the gene bank) with avian influenza virus strains previously found in wild birds or poultry monitored around the world, in order to determine which virus strains from which different places may have combined to form this newly discovered avian influenza virus. If the gene source of the virus strain has a record of infecting humans, then special caution is required.

Check whether the 8 gene segments carry H9N2

Virus strains previously reported to have infected humans in mainland China include subtypes such as H7N9, H10N8, H5N6 and H5N1. In the results of analyzing the 8 gene segments, 6 of the internal genes were all derived from H9N2. Therefore, the Animal Health Research Institute of the Council of Agriculture should compare as soon as possible whether the 6 internal gene segments of the recently discovered H5N8 or new and old types of H5N2 avian influenza virus strains are also derived from H9N2, in order to determine the true source of these virus strains and whether there is a risk of infecting humans.

However, regarding these recent waves of avian influenza outbreaks in chickens, ducks and geese, the Animal Health Research Institute analyzed the viruses only by going to the gene bank and comparing which country's avian influenza virus they were similar to, without explaining which subtypes of avian influenza the 8 gene segments of the virus were composed of. Taking the new type of H5N2 as an example, it explained that the H5 of this virus strain is closest to the nucleic acid sequence DNA placed in the gene bank by South Korea in 2014, and the N2 is most similar to a wild bird virus isolated in Jilin Province in 2011. It said the virus was formed by a combination of these two strains and believed it was spread by migratory birds. Such scientific inferential evidence is somewhat weak, and further explanation to the public should wait until the comparison of the 8 gene segments is completed.

In addition, the Animal Health Research Institute explained that the H5N8 virus isolated from sick ducks and sick geese in Taiwan belongs to the same subtype as the highly pathogenic avian influenza outbreak that occurred in South Korea in 2014, and speculated that the transmission route was caused by migratory birds, stressing that the probability of the virus infecting humans is very low. In fact, South Korean research units isolated many different H5N8 virus strains from infected poultry farms and wild bird monitoring. Although they all belong to highly pathogenic avian influenza, analysis of the 8 gene segments found that some internal gene sources may come from avian influenza viruses circulating in the Shandong or Shanghai area of China.

In Shanghai, China, relevant academic and research units also separately found different H5N8 virus strains from monitoring of poultry markets and wild birds in Shanghai. Their genetic similarity is likewise close to the H5N8 that broke out in South Korea in 2014, and they all carry 6 bases belonging to the highly pathogenic type. However, in mouse experiments, it was found that the H5N8 virus strain isolated from poultry markets could infect the lungs of mice, with low lethality, but the H5N8 virus strain isolated from wild birds could already infect the brain of mice and had lethal capability.

Avian influenza is not just a poultry industry issue, but also a public health issue

Therefore, although the newly discovered H5N8 virus strain in Taiwan is up to 99% genetically similar to the H5N8 of the 2014 outbreak in South Korea, which virus strain is it actually closer to? Which subtype of virus strain do the 6 internal genes among the 8 gene segments come from? Is the source the same as H5N1, H7N9 or H10N8, which have previously been transmitted from poultry to humans, in all carrying H9N2? These all involve the formulation of future cross-ministerial epidemic prevention strategies. This is not merely an issue of industry damage that the agricultural authorities worry about, but also a public health issue concerning human lives.

Therefore, whether it is H5N8 or the new and old types of H5N2 virus strains, the Bureau of Animal and Plant Health Inspection and Quarantine and the Animal Health Research Institute should implement information disclosure and release the analysis results of the 8 gene segments to the public as soon as possible.