hemaglutinin and neuraminidase, two surface glycoproteins of influenza that contribute the the virulence of the disease...
Unlike most viruses, the shape of influenza viruses is highly variable; however, their surface is consistently covered with protein spikes .There are eight RNA segments which encode 10 proteins. Two of the proteins, heamagglutinin and neuraminidase, make up the surface spikes. These proteins are antigenic, and antibody to them is what protects humans from influenza. Haemagglutinin (H) is the protein by which the virus attaches to its host cell. At present, there are 15 immunologically and genetically distinct haemagglutinin subtypes. Neuraminidase (N) is an enzyme that plays a role in releasing virions from their host cell, promoting the spread of infection. Nine neuraminidase subtypes have been identified. Only three haemagglutinin and two neuraminidase subtypes are commonly associated with human infections.
Influenza type A and type B are two different strains of the influenza virus. Type A is more common and has the ability to infect animals, while type B primarily infects humans. Type A viruses are categorized into subtypes based on two proteins on the surface of the virus, hemagglutinin (H) and neuraminidase (N), which helps determine their potential to cause pandemics.
Overview:H1N1, H1N2, and H3N2 are the only known Influenza A virus subtypes currently circulating among humans. All the subtypes listed in the question, i.e., H1N1, H1N2, H3N1 and H3N2 are the known subtypes of influenza A viruses that are endemic in pigs and create influenza in pigs, from which reassortants have formed new strains that can be infective to humans. H1N1 is the "swine flu" subtype of influenza, of which there are several different strains. This subtype is usually seen in humans and pigs. The better known reassortant H1N1 virus strain currently circulating is H1N1/09, the pandemic swine flu virus that caused the pandemic of 2009 and infected humans, pigs, birds, ferrets, dogs, and cats during the pandemic. There are several other less well known strains of the H1N1 subtype.H1N2 is a common flu in pigs in the Upper Midwest of the US. Until 2011, only one case had been known to occur in humans and that was in 2007 in Michigan. The second ever known case was found in an infant in December 2011 in Minnesota.H3N1 mostly only infects pigs.H3N2 is the subtype that produced a strain of flu that caused the Hong Kong Flu and another was the cause of the Fujian Flu, etc. In birds, humans, and pigs, there have been many new strains mutated and this subtype is becoming more prevalent in seasonal influenza.For background, the meanings of "H" and "N" in the nomenclature:Hemagglutinin: An important surface protein on the capsid (coat) of the influenza virus that is essential for the reproduction and the spread of the virus in the body in the lytic cycle of virus replication. This protein enables the virus to attach itself to a cell in the respiratory system or other mucous tissue and penetrate it to invade and use the host cell for reproduction. Referred to as the "H" in influenza viruses.Neuraminidase: An important surface structure protein of the influenza virus that is an essential enzyme for the spread of the virus throughout the respiratory tract. It enables the virus to escape the host cell and infect new cells. Referred to as the "N" in influenza viruses.See more about the lytic cycle and influenza virus nomenclature in the related questions below.Types of Influenza VirusesThere are three types of influenza viruses: Types A, B and C. Influenza A and B viruses cause seasonal outbreaks and epidemics of influenza virus infections each flu season. Type A causes all pandemics. Influenza type C infections cause a mild respiratory illness and are not thought to cause epidemics. Influenza A viruses are divided into subtypes based on the configuration of the two proteins on the surface of the viruses: hemagglutinin (H) and neuraminidase (N). [Not all H1N1 viruses are the same; not all H5N1 viruses are the same.....etc] There are 16 different hemagglutinin subtypes and 9 different neuraminidase subtypes. Influenza A viruses can be further broken down into different strains.Influenza B viruses are not divided into subtypes. Influenza B viruses also can be further broken down into different strains.Influenza A (H1N1), A (H3N2), and influenza B strains are included in each year's influenza vaccine. Getting a flu vaccination can protect against influenza A and B viruses. The flu vaccine does not protect against influenza C viruses.More information including how influenza viruses change: Drift and ShiftInfluenza viruses are dynamic and are continuously mutating, reassorting, and evolving. Influenza viruses can change in two different ways: antigenic drift and antigenic shift. Influenza viruses are changing by antigenic drift all the time, but antigenic shift happens only occasionally. Influenza type A viruses undergo both kinds of changes; influenza type B viruses change only by the more gradual process of antigenic drift. Antigenic drift refers to small, gradual changes that occur through point mutations in the two genes that contain the genetic material to produce the main surface proteins, hemagglutinin, and neuraminidase. These point mutations occur unpredictably and result in minor changes to these surface proteins. Antigenic drift produces new virus strains that may not be recognized by antibodies produced after exposure to earlier influenza strains.This process works as follows: a person infected with a particular influenza virus strain develops antibodies against that strain. As newer virus strains appear, the antibodies against the older strains might not recognize the "newer" virus to inactivate it, and infection with a new strain can occur. This is one of the main reasons why people can become infected with influenza viruses more than one time and why global surveillance is critical in order to monitor the evolution of human influenza virus stains for selection of which strains should be included in the annual production of influenza vaccine.In most years, one or two of the three virus strains in the seasonal influenza vaccine are updated to keep up with the changes in the circulating influenza viruses. For this reason, people who want to be immunized against influenza need to be vaccinated every year.Antigenic shift refers to an abrupt, major change to produce a novel influenza A virus subtype in humans that had not been currently circulating among people (see more information below under Influenza Type A and Its Subtypes).Antigenic shift can occur either through direct animal (poultry)-to-human transmission or through mixing of human influenza A and animal influenza A virus genes to create a new human influenza A subtype virus through a process called genetic reassortment or reassortant. Antigenic shift results in a new human influenza A subtype.A global influenza pandemic (worldwide spread) may occur if three conditions are met:A new subtype of influenza A virus is introduced into the human population.The virus causes serious illness in humans.The virus can spread easily from person to person in a sustained manner.
Usually 'H' on a weather map indicates an area of High pressure.
H = hydrogen O = oxygen N = nitrogen Ne = neon Hydrogen is smallest, so H is the answer.
All Type A influenza viruses have H and N (these are two proteins that are on the outer shell of the virus particle--Hemagglutinin and Neuraminidase). The other influenza virus types B and C each only have one serotype and they do not include the H and N.
The H and N stand for the two proteins on the capsid (coat) of the virion that causes this influenza. The H stands for Hemagglutinin, and the N stands for Nueraminidase. The numbers in the names of flu viruses refer to the configuration of these proteins. See the related questions below for more details.
The term "H1 virus" typically refers to influenza A viruses that are categorized based on their hemagglutinin (H) and neuraminidase (N) proteins. These viruses can cause seasonal flu outbreaks in humans and can also lead to more serious pandemics. Influenza A(H1N1) viruses, for example, were responsible for the 2009 swine flu pandemic.
The naming convention for influenza viruses typically includes the type of virus (A, B, C, or D), the host species (if not human), the location of isolation, the strain number, and the year of isolation. For example, an influenza A virus might be named "A/California/07/2009," where "A" indicates the type, "California" is the location, "07" is the strain number, and "2009" is the year. In the case of subtype A viruses, the hemagglutinin (H) and neuraminidase (N) protein subtypes are also included, such as "A/H1N1."
Background information about names of flu virus strains:For background, H1N1 is the name used to identify several subtypes of flu viruses. A few of the influenza viruses that are in the group of Type A Influenza viruses are labeled that way or in similar ways.These influenza A virus strains are categorized according to two proteins found on the surface of the virus: hemagglutinin (H) and neuraminidase (N). All influenza A viruses contain hemagglutinin and neuraminidase, but the structure of these proteins differ from strain to strain due to rapid genetic mutation in the viral genome.Influenza A virus strains are assigned an H number and an N number based on which forms of these two proteins the strain contains. There are 16 H and 9 N subtypes known in birds, but only H 1, 2 and 3, and N 1 and 2 are commonly found in humans. There are also Influenza type B viruses.Example Swine Flu:An example is the new "Swine Flu" virus circulating in 2009, the "Influenza A, Novel H1N1/09" Virus. It evolved from a virus that started as a flu that only pigs could get, which is called H1N1, too. But that mutated to a strain that could also infrequently infect humans who were in very close contact with pigs, such as farmers who raised them. The new "Novel H1N1" virus was a further mutation that combined human, bird, and swine flu genes.The Centers for Disease Control and Prevention and World Health Organization call the pandemic 2009 "Swine Flu": Influenza A, Novel H1N1 Virus. You may also see it written as the "Novel H1N1 Influenza virus", or "Novel Influenza A, H1N1 virus", or "H1N1, formerly Swine Flu".It has different names in other countries as well, for example: it is called Schweinegrippe in Germany, la Grippe A in France, Mexican Flu in the Netherlands, SOIV (Swine Origin Influenza Virus) in Canada, and la epidemia in Mexico.The reason they call it "Novel" is that it is new. It is a strain not seen before. There are other strains of H1N1 influenza, but this one has different and new genetic material than the previously seen strains of Type A flu.What A-H1N1 means:"A" stands for the influenza sub-type or strain.These Type A viruses have a protein coating that surrounds them, called a capsid. The surface proteins making up the capsid in these virus strains are Hemagglutinin and Neuraminidase. These surface proteins are the parts of a virus that can be changed when viruses mutate into new forms. This is how they change to be able to attack the cells of new hosts or in new ways in the same hosts. They are no longer recognized as viruses that the immunological system of the host has fought before, and that allows them to mutate to forms that can evade the body's defenses again at first.In the naming convention of viruses, the protein classifications become part of the name as in H1N1; H for the Hemagglutininand N for the Neuraminidase. Hemagglutinin binds the virus to the cell it is infecting. Neuraminidase is an enzyme that lets the virus be released from the host carrier cell.There are different subtypes of viruses using the H and N nomenclature, for example the H5N1 subtype is the Avian (Bird) Flu.
In H5N1, the 'H' stands for hemagglutinin and the 'N' stands for neuraminidase. These are two proteins found on the surface of the influenza virus. The numbers indicate the specific subtype of these proteins, with H5 referring to a particular variant of hemagglutinin and N1 indicating a specific variant of neuraminidase. This classification helps in identifying and studying different strains of the virus.
Unlike most viruses, the shape of influenza viruses is highly variable; however, their surface is consistently covered with protein spikes .There are eight RNA segments which encode 10 proteins. Two of the proteins, heamagglutinin and neuraminidase, make up the surface spikes. These proteins are antigenic, and antibody to them is what protects humans from influenza. Haemagglutinin (H) is the protein by which the virus attaches to its host cell. At present, there are 15 immunologically and genetically distinct haemagglutinin subtypes. Neuraminidase (N) is an enzyme that plays a role in releasing virions from their host cell, promoting the spread of infection. Nine neuraminidase subtypes have been identified. Only three haemagglutinin and two neuraminidase subtypes are commonly associated with human infections.
N. H. Acheson has written: 'Fundamentals of molecular virology' -- subject(s): Molecular virology, Virus Physiological Phenomena, Viruses, Genetics
It is best to clearly express what your question is and avoid unnecessary verbiage. For example, ask "what are the protein receptors on an influenza virus" instead of "what is H and N on influenza?"
Influenza type A and type B are two different strains of the influenza virus. Type A is more common and has the ability to infect animals, while type B primarily infects humans. Type A viruses are categorized into subtypes based on two proteins on the surface of the virus, hemagglutinin (H) and neuraminidase (N), which helps determine their potential to cause pandemics.
Overview:H1N1, H1N2, and H3N2 are the only known Influenza A virus subtypes currently circulating among humans. All the subtypes listed in the question, i.e., H1N1, H1N2, H3N1 and H3N2 are the known subtypes of influenza A viruses that are endemic in pigs and create influenza in pigs, from which reassortants have formed new strains that can be infective to humans. H1N1 is the "swine flu" subtype of influenza, of which there are several different strains. This subtype is usually seen in humans and pigs. The better known reassortant H1N1 virus strain currently circulating is H1N1/09, the pandemic swine flu virus that caused the pandemic of 2009 and infected humans, pigs, birds, ferrets, dogs, and cats during the pandemic. There are several other less well known strains of the H1N1 subtype.H1N2 is a common flu in pigs in the Upper Midwest of the US. Until 2011, only one case had been known to occur in humans and that was in 2007 in Michigan. The second ever known case was found in an infant in December 2011 in Minnesota.H3N1 mostly only infects pigs.H3N2 is the subtype that produced a strain of flu that caused the Hong Kong Flu and another was the cause of the Fujian Flu, etc. In birds, humans, and pigs, there have been many new strains mutated and this subtype is becoming more prevalent in seasonal influenza.For background, the meanings of "H" and "N" in the nomenclature:Hemagglutinin: An important surface protein on the capsid (coat) of the influenza virus that is essential for the reproduction and the spread of the virus in the body in the lytic cycle of virus replication. This protein enables the virus to attach itself to a cell in the respiratory system or other mucous tissue and penetrate it to invade and use the host cell for reproduction. Referred to as the "H" in influenza viruses.Neuraminidase: An important surface structure protein of the influenza virus that is an essential enzyme for the spread of the virus throughout the respiratory tract. It enables the virus to escape the host cell and infect new cells. Referred to as the "N" in influenza viruses.See more about the lytic cycle and influenza virus nomenclature in the related questions below.Types of Influenza VirusesThere are three types of influenza viruses: Types A, B and C. Influenza A and B viruses cause seasonal outbreaks and epidemics of influenza virus infections each flu season. Type A causes all pandemics. Influenza type C infections cause a mild respiratory illness and are not thought to cause epidemics. Influenza A viruses are divided into subtypes based on the configuration of the two proteins on the surface of the viruses: hemagglutinin (H) and neuraminidase (N). [Not all H1N1 viruses are the same; not all H5N1 viruses are the same.....etc] There are 16 different hemagglutinin subtypes and 9 different neuraminidase subtypes. Influenza A viruses can be further broken down into different strains.Influenza B viruses are not divided into subtypes. Influenza B viruses also can be further broken down into different strains.Influenza A (H1N1), A (H3N2), and influenza B strains are included in each year's influenza vaccine. Getting a flu vaccination can protect against influenza A and B viruses. The flu vaccine does not protect against influenza C viruses.More information including how influenza viruses change: Drift and ShiftInfluenza viruses are dynamic and are continuously mutating, reassorting, and evolving. Influenza viruses can change in two different ways: antigenic drift and antigenic shift. Influenza viruses are changing by antigenic drift all the time, but antigenic shift happens only occasionally. Influenza type A viruses undergo both kinds of changes; influenza type B viruses change only by the more gradual process of antigenic drift. Antigenic drift refers to small, gradual changes that occur through point mutations in the two genes that contain the genetic material to produce the main surface proteins, hemagglutinin, and neuraminidase. These point mutations occur unpredictably and result in minor changes to these surface proteins. Antigenic drift produces new virus strains that may not be recognized by antibodies produced after exposure to earlier influenza strains.This process works as follows: a person infected with a particular influenza virus strain develops antibodies against that strain. As newer virus strains appear, the antibodies against the older strains might not recognize the "newer" virus to inactivate it, and infection with a new strain can occur. This is one of the main reasons why people can become infected with influenza viruses more than one time and why global surveillance is critical in order to monitor the evolution of human influenza virus stains for selection of which strains should be included in the annual production of influenza vaccine.In most years, one or two of the three virus strains in the seasonal influenza vaccine are updated to keep up with the changes in the circulating influenza viruses. For this reason, people who want to be immunized against influenza need to be vaccinated every year.Antigenic shift refers to an abrupt, major change to produce a novel influenza A virus subtype in humans that had not been currently circulating among people (see more information below under Influenza Type A and Its Subtypes).Antigenic shift can occur either through direct animal (poultry)-to-human transmission or through mixing of human influenza A and animal influenza A virus genes to create a new human influenza A subtype virus through a process called genetic reassortment or reassortant. Antigenic shift results in a new human influenza A subtype.A global influenza pandemic (worldwide spread) may occur if three conditions are met:A new subtype of influenza A virus is introduced into the human population.The virus causes serious illness in humans.The virus can spread easily from person to person in a sustained manner.
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