What Factors Affect the Spread of Swine Flu?

H1N1 subtype swine influenza virus is a strain of influenza A virus. The flu virus was first discovered by Britishman Wilson Smith in 1933, and he called it H1N1. H stands for hemagglutinin; N stands for neuraminidase. The numbers represent different types. Scientists have detected H1N1 subtype swine influenza virus strains in patients, so this flu has become "swine flu", but this new type of influenza virus has virus hybridization characteristics.

H1NI swine flu

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H1N1 subtype

H1N1 subtype

According to the objects infected by the influenza virus, the viruses can be divided into human influenza virus, swine influenza virus, equine influenza virus, and avian influenza virus. The human influenza virus can be divided into three types according to the antigenicity of its nuclear protein:

The 8-plasmid rescue system successfully rescued the swine influenza virus strain A / Swine / TianJin / 01/2004 (H1N1) (A / S / TJ / 04). Eight swine influenza virus gene segments were synthesized by RT-PCR and cloned into the RNA polymerase I / II two-way expression vector PHW2000 to construct eight recombinant plasmids. COS-1 cells were co-transfected with 8 recombinant plasmids, and 30 hours later, TPCK-trypsin was added to a final concentration of 0.5 g / mL.
COS-1 cells and their supernatants were harvested 48 hours after total transfection, and 9-day-old SPF chicken embryos were inoculated through the allantoic cavity. The allantoic fluid of dead chicken embryos was harvested and continued to be transmitted for three generations with SPF chicken embryos to obtain infectious virus. Hemagglutination, hemagglutination inhibition test, sequencing analysis, and electron microscope observations confirmed the successful rescue of A / S / TJ / 04 swine influenza virus.
This is the first time that China has rescued the H1N1 subtype swine influenza virus, laying a foundation for further studying the relationship between the genome structure and function of the swine influenza virus, the mechanism of influenza cross-species transmission, and the construction of a new swine influenza vaccine strain.

Swine influenza virus (Swine influenza virus, SIV) is an orthomyxoviruses that can cause endemic influenza in pigs. The viruses currently isolated in the laboratory are mostly identified as influenza C virus or one of the subspecies of influenza A virus. There are many different types of influenza A virus swine flu under the electron microscope, including: H1N1, H1N2, H3N1, H3N2, and H2N3 subtype A influenza viruses can cause swine influenza infection.
Sequence analysis of HA and NA genes of swine influenza viruses isolated from China and existing swine influenza virus H1N1, H1N2 and H3N2 subtype strains in the GenBank database, and the HA and NA genes of each virus subtype were selected, respectively Highly conserved and specific nucleotide regions in the medium, two sets of multiplex PCR-specific primers designed to amplify swine influenza virus H1 and H3, N1, and N2 subtypes were established, and a multiple RT- PCR diagnostic methods.
This method was used to perform RT-PCR tests on standard reference strains of H1N1, H1N2, and H3N2 subtype swine influenza viruses, and the results were positive. The amplified fragments were sequenced and compared with BLAST to indicate that they were the target gene fragments. Common swine disease viruses and other subtypes of swine influenza viruses were negative for RT-PCR. The 107 EID50 / 0.1 mL virus was diluted and RNA was extracted for sensitivity tests. RT-PCR could detect at least 102 EID50 viruses. Amount of nucleic acid.
The test results of 40 positive clinical samples were 16, 1, and 20 H1N1, H1N2, and H3N2 subtypes, and the other 3 samples contained both H1N1 and H3N2 subtype swine influenza viruses, and the chicken embryo isolated virus was 100. The test proves that the established swine influenza virus H1N1, H1N2 and H3N2 subtype multiple RT-PCR diagnostic method is a specific and sensitive diagnostic method, which can be used for early rapid diagnosis and typing of clinical samples.

An acute respiratory infection caused by the H1N1 swine influenza virus is rarely transmitted to humans. People infected with the swine flu virus will develop symptoms such as high fever, loss of energy, anorexia, and cough. Officials from the US Centers for Disease Control and Prevention have pointed out that the swine flu virus strain is a peculiar hybrid that contains human influenza virus, avian influenza virus and swine flu virus gene fragments. The symptoms of infected persons are similar to those of ordinary influenza virus infected persons.

Experts from the World Health Organization warn that the difference between flu is that patients are mostly young people who are physically strong, rather than vulnerable people such as the elderly and children who are usually vulnerable to flu. One of the severe flu signatures of mass deaths. Data show that in the global influenza outbreak of 1918, 40 million people died worldwide, and the patients who died in the early stages of the epidemic were all young people with strong health.

Medical tests show that current mainstream antiviral drugs are effective against this strain. At present, the medical community has not developed any vaccine against swine flu, and it is unknown whether the influenza vaccine already in use can provide protection.
Swine flu infections in humans are rare, and swine flu viruses rarely spread from person to person. From December 2005 to January this year, only 12 cases of human swine flu were found in the United States, of which 11 had direct contact with pigs.
The WHO issued a statement saying that they are stockpiling the antiviral drug "Duffy", oseltamivir phosphate, phosphate of oseltamivir, and chemical substance registration number CASRN 204255-11-8. The drug was previously widely used to control bird flu and has also been tested against the new swine flu virus.

Because H1N1 subtype swine influenza virus is similar to human H1N1 virus.

The same point 1: both can be cross-infected from person to person, the transmission route is similar 2: the medical ratio of infection is similar (both 1: 1 to 1:15)
3: Both have a little degree of universal resistance, but not extensive resistance 4: Both are transmitted from animals to humans 5: Both are fatal, but can be effectively controlled 6: Both have a little time Incubation period (SIV is slightly shorter), and the early symptoms are similar to common diseases. 7: Both can be controlled by reasonable daily preventive measures. 1. The SIV gene fragment is more complicated and is a mutant virus (the original SIV cannot. Spread among people)
2: The susceptible population of SIV is adolescents and their middle-aged adults, which is very special. 3: SIV is not effective against two of the current four anti-influenza virus drugs. 4: SIV patients have different symptoms, which is similar to common infections. The disease is quite different