"Chinese Academy of Sciences found that the novel H7N9 virus as China and South Korea "hybrid"

HATTIP CATBIRD

Apr. 08, 2013

The new type of the H7N9 avian influenza virus genes from wild birds Korea and China in Shanghai, Zhejiang, Jiangsu flocks gene reassortment

Network】 【Finance (Reporter Wang Chen) new avian influenza virus H7N9 in China, the number of infections rising, as of April 8, to 24, the number of infections and deaths increased to seven cases. Such a low-morbidity in poultry, the viruses that cause high mortality in humans, caused by the high degree of concern in the scientific community. H7N9 avian influenza virus, one of the most important direction - gene traceable Recently, some preliminary conclusions.

Institute of pathogenic microorganisms and Immunology Key Laboratory researchers said the new financial reporter April 8, the reassortant virus fragments of the Laboratory results showed that the eight gene segments of the H7N9 avian flu virus, H7 fragment derived from Zhejiang avian influenza virus isolated in ducks, and Zhejiang ducks virus up retrospective homologous with the avian influenza virus isolated Korean wild birds; homology of the avian influenza virus isolated N9 fragment of wild birds in Korea. The remaining six gene segments (PB2, PB1, PA, NP, M, NS) derived from the H9N2 avian influenza virus. According to the viral genome comparison and phylogenetic analysis, H9N2 avian influenza virus from flocks of China in Shanghai, Zhejiang, Jiangsu and other places.

Gene reassortment likely occurred in China's Yangtze River Delta region. Process possibly via Korea of ​​wild birds in the natural migration process, and the Yangtze River Delta region of China, ducks, chickens with its own bird flu virus gene reassortment produce. The results also show that the H7N9 avian influenza virus evolution traces, yet found in pigs and that pigs do not play the role of intermediate host in this viral gene reassortment.

Korean wild birds

Avian influenza virus is composed of eight gene fragment, including the HA, NA, PB2, PB1, PA, NP, M, NS, virus named determined by these two genes HA, NA name, each of the middle of the 6 "family members" not identical. Is also known as the H7N9 virus, is not necessarily the same. This different from the gaggle in the Czech Republic in 2009, found that the H7N9 avian influenza virus H7N9 found in mainland China, is also different from the H7N9 avian influenza virus isolated from wild ducks in Korea in 2008, three common virus only is that the same N9, the remaining seven genes are not the same - they are collectively referred to as the H7N9 subtype.

Very important as the name of the virus HA, NA gene fragment Two glycoproteins protrusions on the surface of the influenza virus, hemagglutinin (HA) like virus used to open and the invasion of the keys to the cells of humans or livestock, nerve ammonia acid enzymes (NA), can destroy the cell receptors, help virus spread freedom in the host body. Can be divided into 16 kinds of HA, NA can be divided into nine kinds. Different combinations between them, the theoretical maximum can be combined into 144 different virus subtypes, in reality, it has been found more than 130 species.

Continuous generation of reassortant viruses in nature, different virus through contact with their respective host another exchange of gene fragments. The H7N9 avian flu virus found in the Chinese mainland, in the nature of the spread process is likely to follow the following path: migratory the Korean wild bird carrying H subtypes (including H7N3 and H7N9 subtype avian influenza virus) to the Yangtze River Delta region of China, the contact Zhejiang ducks, the virus reassortant ducks carrying the H7 subtype viruses, ducks are likely as an intermediate host, and Zhejiang, Shanghai and other places carrying H9N2 avian influenza virus in chickens contact eventually gene reassortment become the new avian flu virus H7N9.

Break the person poultry barrier

According to the traditional experience of the avian flu virus, regardless of the poultry is low pathogenic virus or high pathogenic virus, are more difficult to infect human cells, generally after the human respiratory tract Jibei stand in the way.

Reality and research revealed that the original virus circulating in poultry, or through an intermediate host pig gene reassortment infected person;, or directly from poultry to people. The H7N9 avian influenza virus, that is, directly from birds to people. The danger is that this presents a low pathogenic virus in birds who was devastating in the human body, the virus replicated in human lungs crazy, very rapid progression of the disease, the mortality rate is also high.

In accordance with the mechanism of virus structure, the process of the virus invades the human body like a teamwork combat is divided into three steps: HA like a key breakthrough who host limit; NA helps the virus destroys the cell receptor so that the new copy synthesis spread of the virus the remaining six gene fragments collaboration, and the completion of the virus to copy a large number of cells in the body, three steps with the lack of a non-Which one imbalance can be caused by viruses strength weakening, difficult to play killing effect on the human body.

Unfortunately, these three steps efficient havoc with the human body in a new type of H7N9 avian influenza virus. According to experts, research, resulting in new H7N9 avian influenza virus to infect humans and cause high mortality from the virus mutates.

"N9 mutation has been observed the N9 gene fragment is shorter than the N9 gene fragments, but still I do not know this variation lead to what specific consequences". The above researchers said.

This change in the course of the study, the the H7 gene fragments and customary H7 has not changed much, but in people - avian receptor binding specificity, critical amino acid changes in determining people affect pending further scientific assessment. H7 subtypes of avian influenza virus infection case had occurred.

From 1959 to 2007, 112 cases of infections in the United States, Australia and the Netherlands, but showed a slight, only conjunctivitis and mild flu-like symptoms, H7 subtypes of avian influenza virus has been unaffected the attention of the scientific community."