Influenza A H3N2 virus subtype ( A/H3N2 ) is a subtype of the virus that causes influenza (flu). H3N2 virus can infect birds and mammals. In birds, humans, and pigs, viruses have mutated into many strains. H3N2 is increasingly abundant in seasonal influenza.
Video Influenza A virus subtype H3N2
Classification
H3N2 is a subtype of the genus Influenzavirus A virus, which is an important cause of human influenza. Its name comes from the form of two types of proteins on the surface of its mantle, hemagglutinin (H) and neuraminidase (N). With reassortment, H3N2 exchanges genes for internal proteins with other influenza subtypes.
Maps Influenza A virus subtype H3N2
Seasonal H3N2 flu
Seasonal influenza kills about 36,000 people in the United States every year. The flu vaccine is based on predictions that "mutants" from H1N1, H3N2, H1N2, and influenza B will proliferate in the following season. Separate vaccines are developed for the Northern and Southern Hemisphere in preparation for their annual epidemic. In the tropics, influenza does not show clear seasons. In the last ten years, H3N2 tends to dominate the prevalence of H1N1, H1N2, and influenza B. The measured resistance to standard antiviral drugs amantadine and rimantadine in H3N2 has increased from 1% in 1994 to 12% in 2003 to 91% in 2005.
Seasonal H3N2 flu is a human flu of H3N2 which is slightly different from one of last season's H3N2 flu season variants. Seasonal influenza virus flows out of overlapping epidemics in East Asia and Southeast Asia, then trickles across the world before dying. Identifying virus sources allows global health workers to better predict which viruses are most likely to cause the most diseases over the next year. An analysis of 13,000 samples of A/H3N2 influenza viruses collected on six continents from 2002 to 2007 by the WHO Global Influenza Surveillance Network showed a newly emerging H3N2 strain emerging in East and Southeast Asian countries about six to nine months earlier than where only. other. The strains generally reach Australia and New Zealand next, followed by North America and Europe. New variants usually reach South America after an additional six to nine months, the group reported.
Swine flu
A 2007 study reported: "In pigs, three subtypes of influenza A (H1N1, H3N2 and H1N2) viruses are circulating worldwide.In the United States, classical H1N1 subtypes were exclusively prevalent among pig populations before 1998, but since late August 1998, H3N2 subtypes have been isolated from pigs, most of the H3N2 virus isolates are three reassortants, containing genes from humans (HA, NA, and PB1), pigs (NS, NP, and M), and poultry lineages (PB2 and PA) Strategies the current vaccination for the control and prevention of swine influenza virus (SIV) in pig farms typically includes the use of one of the few commercially available SIV vaccines available in the United States Of the 97 recently investigated H3N2 isolates, only 41 has a strong cross-serological reactions with antiserum for three commercial SIV vaccines Because influenza vaccine protection capability is highly dependent on the proximity of the match between the vaccine virus and the epidemic virus, ran H3N2 SIV that is not reactive Variants suggest that current commercial vaccines may not effectively protect pigs from infection with most H3N2 viruses. "
The Avian influenza H3N2 virus is endemic to pigs in China, and has been detected in pigs in Vietnam, contributing to the emergence of new variants. Pigs can carry human influenza viruses, which can combine (ie exchange homologous genome subunit by genetic reassortment) with H5N1, passing genes and mutating into a form that can easily pass through humans. H3N2 evolved from H2N2 by antigenic shift and caused the Hong Kong flu pandemic of 1968 and 1969 that killed up to 750,000 people. The dominant strain of the annual flu in humans in January 2006 was H3N2. Resistance measured against the standard antiviral drugs amantadine and rimantadine in H3N2 in humans has increased to 91% in 2005. In August 2004, researchers in China found H5N1 in pigs.
The spread of flu, seasonal
Hong Kong Flu (1968-1969)
The Hong Kong Flu is a category 2 flu pandemic caused by the H3N2 strain derived from H2N2 by an antigenic shift, in which the genes of several subtypes are reinforced to form a new virus. The 1968 and 1969 pandemics killed one million people worldwide. This pandemic infects about 500,000 Hong Kong residents, 15% of the population, with a low mortality rate. In the United States, about 33,800 people died.
Both the H2N2 and H3N2 pandemic flu strains contain genes from avian influenza viruses. New subtypes appear in pigs co-infected with avian and human viruses and are immediately transferred to humans. Pigs are considered genuine "brokers" for influenza, as they support different subtype reassortment. However, other hosts appear to have similar co-infections (eg, many avian species), and direct transmission of avian virus to humans is possible. H1N1 may have been transmitted directly from bird to human (Belshe 2005).
The Hong Kong flu strain shares the internal genes and neuraminidases with the Asian flu 1957 (H2N2). Antibodies accumulated in neuraminidase or internal proteins may have resulted in fewer casualties than most pandemics. However, cross-immunity within and among influenza subtypes is poorly understood.
Hong Kong flu is the first known H3N2 outbreak, despite serological evidence from H3N? infection at the end of the 19th century. The first record of the epidemic in Hong Kong appeared on July 13, 1968 in an area with a density of about 500 people per acre in urban environments. The outbreak reached its maximum intensity in two weeks, lasting six weeks in total. The virus was isolated at the Queen Mary Hospital. Symptoms of the flu lasted four to five days.
In July 1968, an extensive outbreak was reported in Vietnam and Singapore. In September 1968, he reached India, the Philippines, northern Australia and Europe. That same month, the virus entered California from restoring troops to the Vietnam War. It reached Japan, Africa, and South America in 1969.
"Three strains of the Hong Kong influenza virus were isolated from humans compared with strains isolated from the calf because of their ability to cause disease in calves One of the human strains A/Aichi/2/68, detected for five days in the calf, but all three fails to cause signs of disease.A/cal/Duschanbe/55/71 strains can be detected for seven days and cause diseases like influenza in the calf. "
Flu Fujian (2003-2004)
Fujian flu refers to flu caused by Fujian human flu strain from H3N2 subtype or Fujian bird flu strain from H5N1 subtype of Influenza A virus. This strain is named after Fujian province in China.
A/Fujian (H3N2) human flu (from the A/Fujian/411/2002 (H3N2) flu virus strain) caused a very severe 2003-2004 flu season. This is due to reassortment events that cause minor clade to provide haemagglutinin genes which later became part of the dominant strain in the 2002-2003 flu season. A/Fujian (H3N2) was made part of the trivalent influenza vaccine for flu season 2004-2005.
2004-2005 flu season
The 2004-05 trivalent influenza vaccine for the United States contains:
- virus A/New Caledonia/20/99 (H1N1) -like
- A/Fujian/411/2002 (H3N2) virus-like
- virus B/Shanghai/361/2002-like.
flu season 2005-2006
Vaccines produced for the 2005-2006 season are used:
- A/New Caledonia/20/1999-like (H1N1)
- A/California/7/2004-like (H3N2) (or equivalent A/New York/55/2004 antigen strain)
- B/Jiangsu/10/2003-like virus
flu season 2006-2007
The 2006-2007 influenza vaccine composition recommended by the World Health Organization on February 15, 2006 and the US FDA Vaccine and Related Biological Product Advisory Committee on February 17, 2006 used:
- virus A/New Caledonia/20/99 (H1N1) -like
- A/Wisconsin/67/2005 (H3N2) viruses-like (A/Wisconsin/67/2005 and A/Hiroshima/52/2005)
- a B/Malaysia/2506/2004-like virus from B/Malaysia/2506/2004 and B/Ohio/1/2005 strain derived from B/Victoria/2/87 lineage
flu season 2007-2008
The composition of the influenza virus vaccine for use in the Northern Hemisphere season 2007-2008 recommended by the World Health Organization on 14 February 2007 is:
- virus A/Solomon Islands/3/2006 (H1N1) -like
- A/Wisconsin/67/2005 (H3N2) viruses-like (A/Wisconsin/67/2005 (H3N2) and A/Hiroshima/52/2005 used at the time)
- virus B/Malaysia/2506/2004-like
"A/H3N2 has become the dominant flu subtype in the United States, and records over the last 25 years suggest that H3N2-dominated seasons tend to be worse than those dominated by type A/H1N1 or type B." Many H3N2 viruses make people sick in flu season 2007-2008 is different from strains in the vaccine and may not be covered properly by vaccine strains. "The CDC has analyzed 250 viruses this season to determine how well they fit the vaccine, said the report.From 65 H3N2 isolates, 53 (81%) were marked as A/Brisbane/10/2007-like, variants that have evolved [mainly] H3N2 strain in vaccine - A/Wisconsin/67/2005. "
2008-2009 flu season
The composition of the viral vaccine for use in the Northern Hemisphere 2008-2009 season recommended by the World Health Organization on February 14, 2008 is:
- virus A/Brisbane/59/2007 (H1N1) -like
- virus A/Brisbane/10/2007 (H3N2) -like
- B/Florida/4/2006-like (B/Florida/4/2006 and B/Brisbane/3/2007 viruses (B/Florida/4/2006-like viruses) were used at the time)
On May 30, 2009: "The CDC antigen characterized 1,567 seasonal human influenza viruses [947 influenza A (H1), 162 influenza A (H3) and 458 influenza B viruses] collected by US laboratories since October 1, 2008, and 84 novel influenza viruses A (H1N1) All 947 seasonal influenza virus A (H1) is associated with influenza A (H1N1) influenza vaccine component component 2008-09 (A/Brisbane/59/2007).All 162 influenza A (H3N2) viruses are associated with vaccine component A ( H3N2) (A/Brisbane/10/2007) All 84 new influenza A (H1N1) viruses linked to A/California/07/2009 (H1N1) virus references selected by the WHO as potential candidates for new influenza A (H1N1) virus vaccine Current influenza B can be divided into two distinct lineages represented by the B/Yamagata/16/88 and B/Victoria/02/87 viruses. Sixty-one influenza B viruses are tested belonging to the B/Yamagata lineage and are related to strain vaccine (B/Florida/04/2006). Residual 397 virus b elo ng to the B/Victoria lineage and not related to the vaccine strain. "
flu season 2009-2010
Vaccines produced for the 2009-2010 season are used:
- virus A/Brisbane/59/2007 (H1N1) -like
- virus A/Brisbane/10/2007 (H3N2) -like
- a B/Brisbane 60/2008-like antigens
Separate vaccine is available for H1N1 influenza pandemic using A/California/7/2009 pandemic H1N1 strain.
flu season 2010-2011
Vaccines produced for the 2010-2011 season are used:
- A/California/7/2009-like (H1N1 pandemic)
- virus similar to A/Perth/16/2009-like (H3N2)
- B/Brisbane/60/2008-like antigen
flu season 2011-2012
Vaccines produced for the 2011-2012 season are used:
- virus A/California/07/2009 (H1N1) -like
- A/Victoria/210/2009 (strain A/Perth/16/2009-like) (H3N2) -as a virus
- B/Brisbane/60/2008-like virus
flu season 2012-2013
Vaccines produced for the Northern Hemisphere 2012-2013 season are used:
- virus A/California/07/2009 (H1N1) -like
- A/Victoria/361/2011 (H3N2) virus-like
- B/Massachusetts/2/2012-like virus, which replaces the B/Wisconsin/1/2010-like virus
So far this season, the vast majority (91%) of influenza viruses have been analyzed on CDC such as the virus that is included in influenza vaccine 2012-2013.
In January 2013, influenza activity continues to increase in the United States and most of these countries are now experiencing high levels of influenza-like-illness (ILI), according to the latest CDC FluView report. Reports of influenza-like-illness (ILI) approach peak levels during a fairly severe season, and the CDC continues to recommend influenza vaccinations and antiviral treatment when appropriate at present.
On January 9, 2013, the Boston Government announced the Emergency Public Health for H3N2 Flu Epidemic.
One factor that could indicate increased severity this season is that the dominant influenza virus type in circulation is the Influenza A (H3N2) virus, which accounts for about 76 percent of the reported virus. Typically, the H3N2 season is more severe, with higher hospitalization and mortality.
flu season 2014-2015
Vaccines produced for the Northern Hemisphere 2014-2015 season are used:
- A/California/7/2009 (H1N1) viruses such as pdm09
- A/Texas/50/2012 (H3N2) Viruses like
- B/Massachusetts/2/2012-like virus,
The quadrivalent vaccine includes B/Brisbane/60/2008-like virus. CDC announces that drift variants of the A (H3N2) strain of 2012-2013 potentially predict a severe flu season for 2014-2015.
flu season 2015-2016
Vaccines produced for the Northern Hemisphere 2015-2016 season are used:
- A/California/7/2009 (H1N1) viruses such as pdm09
- A/Swiss Virus/9715293/2013 (like H3N2)
- B/Phuket/3073/2013-like virus. (This is a B/Yamagata bloodline)
The "Split Virion" vaccine that is distributed in 2016 contains the following strains of inactivated virus:
- A/California/7/2009 (H1N1) pdm09 - strains such as (A/California/7/2009, NYMC X-179A)
- A/Hong Kong/4801/2014 (H3N2) - likes tension (A/Hong Kong/4801/2014, NYMC X-263B)
- B/Brisbane/60/2008 - likes tension (B/Brisbane/60/2008, wild type)
2016-2017 flu season
- A/California/7/2009 (H1N1) virus pdm09,
- A/Hong Kong/4801/2014 (like H3N2) virus
- B/Brisbane/60/2008-like virus (B/Victorian lineage)
Vaksin influenza quadrivalen menambahkan:
- B/Phuket/3073/2013-like strain
musim flu 2017-2018
- Virus A/Michigan/45/2015 (H1N1) seperti pdm09
- A/Hong Kong/4801/2014 (H3N2)
- B/Brisbane/60/2008-like virus (B/garis keturunan Victoria)
Quadrivalent influenza vaccine added
- B/Phuket/3073/2013-like [B/Yamagata lineage]
See also
- Influenza outbreak H1N1 2009
- Bird flu
- Dog flu
- Horse flu
- Human flu
- Swine flu
References
Further reading
- Graphic showing mutations of H3N2, amino acids by amino acids, among 207 isolates that are fully sequenced by the Genome Influenza Genome Genome Project.
- Influenza Outbreak A (H3N2), Nepal
- Hot topics - A strain similar to Fujian A influenza
- New Scientist: Bird Flu
External links
- Influenza Research Database Information base on influenza and related information.
Source of the article : Wikipedia
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