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Influenza Hemagglutinin (HA) subtypes and Flu Virus Strains


Q1: How many types are influenzas divided into?


The influenza virus is divided into three main types, Influenza A, Influenza B, and Influenza C, which are distinguished by differences in two major virus surface proteins (Hemagglutinin (HA) and Neuraminidase (NA)). Hemagglutinin (HA) and Neuraminidase (NA) both serve as antigenic determinants found on the surface of the Influenza virus.


Q2: What are the differences between Influenza A, Influenza B, and Influenza C?


Influenza A virus is the most common flu virus infecting humans, animals, and birds. Influenza B infection mostly occurred in humans and it does not branch into multiple subtypes. Infection of influenza C virus does not cause any severe symptom in human or mammals and hence it is not well studied.


Q3: How many subtypes is influenza A divided into?


The influenza A virus can be subdivided into different serotypes based on the type of hemagglutinin and neuraminidase. The "H" in "H1N1" for example refers to hemagglutinin (HA) and "N" in "H1N1" refers to neuraminidase (NA). There are 16 different types of HA and 9 different types of NA, therefore, there are potentially 144 different subtypes of influenza A viruses. Among them, two subtypes of influenza A, H1N1 and H3N2, most commonly infect humans. For each subtype virus, the hemagglutinin gene mutates all the time and hence there are many variants of the same subtype viruses, and hence the need to change the virus strain for seasonal flu vaccines on an annual bases. A list of human influenza A virus is exhibited below.


Q4: How many subtypes is influenza B divided into?


This type of influenza mutates at a rate 2-3 times lower than type A and consequently is less genetically diverse, with only one influenza B serotype. Reduced rate of antigenic change, combined with its limited host range (inhibiting cross species antigenic shift), ensures that pandemics of influenza B do not occur.


Influenza Research Reagents (Hot!)

Influenza virus antigen protein
Product Name Cat No.
Influenza H1N1 (A/California/07/2009) Hemagglutinin 11085-V08H
Influenza H1N1 (A/Puerto Rico/8/1934) Hemagglutinin 11684-V08H
Influenza H1N1 (A/California/04/2009) Hemagglutinin 11055-V08H
Influenza H1N1 (A/California/04/2009) Hemagglutinin 11055-V08B
Influenza H3N2 (A/Aichi/2/1968) Hemagglutinin 11707-V08H
Influenza H3N2 (A/Brisbane/10/2007) Hemagglutinin 11056-V08H
Influenza H5N1 (A/Anhui/1/2005) Hemagglutinin 11048-V08H1
Influenza H3N2 Virus Hemagglutinin Protein 40043-V08H
Influenza H7N9 (A/Anhui/1/2013) Hemagglutinin Protein 40103-V08B
Influenza H1N1 (A/Brisbane/59/2007) Hemagglutinin 11052-V08H
Influenza H5N1 (A/VietNeuraminidasem/1194/2004) Hemagglutinin 11062-V08H1
Influenza H7N9 (A/Anhui/1/2013) Hemagglutinin Protein 40103-V08H
Influenza H5N1 (A/Anhui/1/2005) Hemagglutinin 11048-V08H4
Influenza H1N1 (A/California/07/2009) Hemagglutinin Protein 11085-V08B
Influenza H1N1 Nucleoprotein Protein 11675-V08B
Influenza H1N1 (A/California/07/09) Nucleoprotein Protein 40205-V08B
Influenza H1N1 (A/California/04/2009 )Neuraminidase Protein (Active) 11058-V07B
Influenza H5N1 Neuraminidase (Active) 11676-VNAHC
Influenza H5N1 (A/Hubei/2011) Neuraminidase Protein (Active) 40018-V07H
Influenza H1N1 (A/Puerto Rico/8/34/Mount SiNeuraminidasei) Matrix Protein 1 40010-V07E
Influenza virus antigen antibody
Product Name Cat No.
Influenza H1N1 (Swine Flu 2009) Hemagglutinindy Antibo 11055-MM01
Influenza H1N1 (Swine Flu 2009) Hemagglutinin Antibody 11055-RM05
Influenza H7N9 Hemagglutinin Antibody, Rabbit Pab 40103-RP02
Influenza H1N1 (Swine) Hemagglutinin Antibody 11055-MM09
Influenza H1N1 Hemagglutinin Antibody 11684-RP01
Influenza H1N1 (Swine Flu 2009) Hemagglutinin Antibody 11055-RP02
Influenza H5N1 (Avian Flu) Hemagglutinin Antibody 11048-MM01
Influenza Virus Hemagglutinin Antibody, Rabbit MAb 86001-RM01
Influenza H3N2 Hemagglutinin Antibody 11056-MM03
Influenza H1N1 (Swine Flu 2009) Neuraminidase Antibody 11058-R001