New zoonotic warning? Changes in avian influenza virus could increase risk of transmission to humans

The H3N8 virus has demonstrated its ability to infect and replicate in human bronchial epithelial cells /REUTERS/Dado Ruvic/Illustration

In accordance with World Health Organization (WHO),bird flu, also known as bird flu, This infection which mainly affects birds and caused viruses of the family Orthomyxoviridae. Depending on the subtype, it can be classified as “low pathogenicity or highly pathogenicrepresenting different symptoms in infected birds.

According to WHO, “the most common way the virus enters the territory is through migratory wild birds; while the main Risk factor for bird-to-human transmission He direct or indirect contact with infected animals or with environments and surfaces contaminated with faeces.”

Meanwhile, according to the agency, “the emergence of pathogenic infectious pathologies over the past 20 years and recently outbreaks of zoonotic diseases brought increasing public attention to the fact that diseases come and go between species.” As a result, the investigation found that subtype of avian influenza virus experimenting changes in its compositionwhat could I increase the risk of human infection.

Currently, outbreaks are recorded in different parts of the world. For the case in Argentinaaccording to the latest results analysis of National Agri-Food Health and Quality Service (Senasa) samples from dead animals Bird flu outbreaks exist on the coasts of Puerto Madryna (Chubut Province) and Sierra Grande (Rio Negro), as well as in other parts of the country. However, to date, no human cases have been reported in connection with these outbreaks.

Avian influenza primarily affects birds and is caused by a virus of the Orthomyxoviridae (Getty) family.

In this sense, recent Scientific research conducted by researchers from China and England, raised subtype of avian influenza virus which prevails in Chinese poultry farms experimenting changes that may increase the risk of a disease becoming zoonotic.

Experts who published their findings in a journal Cell, belong to the University of Nottingham, the Chinese Agricultural University in Beijing, the Chinese Academy of Sciences and the Chinese Center for Disease Control and Prevention. In the work, they indicated which subtype of the virus they analyzed.

“One of the H3N8 avian influenza (AIV) viruses in China caused two confirmed human infections in 2022, followed by one death in 2023. H3N8 viruses are widespread in chicken flocks; however, the zoonotic characteristics are not well understood. Here we have demonstrated that they are able to efficiently infect and replicate in normal organotypic human bronchial epithelial cells and lung epithelial cells.”

Using laboratory mice and ferrets as models of human infection, the study found that the virus had undergone several adaptive changes. These modifications allow it to cause serious infections in animals and be airborne between animals.

Altered H3N8 virus prevalent in Chinese poultry farms may increase risk of human transmission /EFE/Eric S. Lesser

In this vein, one of the authors of the study, Professor Kin-Chow Chang of the University of Nottingham, described: “We have shown that the avian H3N8 virus isolated from a patient with severe pneumonia replicates efficiently in bronchial and lung epithelial cells. man, had an extremely harmful effect on mammals in the laboratory and could be transmitted by airborne droplets.

Secondly, Kin-Chow Chang postulated: “It is important to note that we found that the virus has acquired a preference for binding to the human receptor and to the replacement of amino acids necessary for airborne transmission. Human populations, even those vaccinated against the human H3N2 virus (another subvariant), appear immunologically immune to emerging mammalian-adapted H3N8 viruses and may be vulnerable to epidemic or pandemic-scale infections.”

According to the authors, in humans, infection with the avian H3N8 virus has been shown to cause symptoms such as acute respiratory failure and, in some cases, can be fatal.

“The acid resistance of the influenza virus is also an important barrier that the avian influenza virus must overcome in order to acquire adaptability and infectivity in new mammals or humans, which we studied in this work. The current H3N8 virus has not yet acquired acid resistance. Therefore, we should pay attention to the change in the acid resistance of the new H3N8 virus,” said another of the authors, Professor Jinhua Liu from China Agricultural University in Beijing.

An epidemic of avian influenza A(H5N1) hit the Americas region between 2022 and 2023. In Argentina, outbreaks have recently been found in sea lions (Senas).

More than 200,000 South American sea lions or South American sea lions live on the Atlantic coast of Argentina and usually congregate in colonies. Since August, these animals have suffered a severe infection with a highly pathogenic avian influenza virus.

At the moment, cases of infection of wolves with avian influenza have been confirmed on the coast of 13 cities and towns from Buenos Aires to Tierra del Fuego. In any case, Argentine sea lions are not the only ones affected by the epidemic. They belong to the species Otaria flavescens, which also inhabits the coasts of Peru and Chile; This pathogen also killed more than 3,500 individuals in these countries last summer.

In the meantime, it should be remembered that between 2022 and mainly during 2023, there is an epidemic of avian influenza associated with subtype A(H5N1) in the Americas region. The evolutionarily circulating strain belongs to a group called clade with similar genetic changes to the group that has spread since late 2020 and throughout 2021 through Asia, Africa, Europe and the Middle East. At the end of that year, it was also discovered in North America. The Pan American Health Organization has warned that it is spreading at an “alarming rate” and has a high mortality rate.

Outbreaks in Argentina began to be detected in February past in wild birds and then continued to engage in poultry farming. Because of this, the country lost its avian influenza free status and then regained it in August when outbreaks in poultry were brought under control.

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