The key difference between H1N1 and H3N2 is that H1N1 is a subtype of influenza A virus that contains main surface proteins known as H1 (hemagglutinin1) and N1 (neuraminidase1), while H3N2 is a subtype of influenza A virus that contains main surface proteins known as H3 (hemagglutinin3) and N2 (neuraminidase2).
Influenza A causes influenza in birds and mammals, including humans. This virus belongs to the family Orthomyxoviridae. Influenza virus is an RNA virus categorized into subtypes based on the type of two proteins (hemagglutinin (H) and neuraminidase (N)) on the surface of the viral envelope. Examples include H1N1, H3N2, H5N1, etc. H1N1 and H3N2 are two subtypes of the influenza A virus.
CONTENTS
1. Overview and Key Difference
2. What is H1N1
3. What is H3N2
4. Similarities – H1N1 and H3N2
5. H1N1 vs H3N2 in Tabular Form
6. Summary – H1N1 vs H3N2
What is H1N1?
H1N1 is a subtype of influenza A virus that contains main surface proteins known as H1 (hemagglutinin1) and N1 (neuraminidase1). It is responsible for the 2009 pandemic in both human and pig populations, which is known as swine flu. Moreover, a variant of HNI was also responsible for the Spanish flu in 1919, which killed some 50 million to 100 million people in about one year. In addition, the 1977 Russian flu pandemic was also caused by a variant of HINI.
H1N1 size is around 80 to 120 nm. The genome size of this virus is 13.5 kb. Some strains of H1N1 are endemic in humans. These strains cause a small fraction of influenza-like illnesses and a small fraction of seasonal influenza. Other strains of HIN1 include an endemic in pigs called swine influenza and an endemic in birds called avian influenza. Furthermore, pregnant women who contract the H1N1 infection are at higher risk of developing complications. Therefore, they are vaccinated against H1N1. Pregnant women already infected are usually given antiviral medications such as oseltamivir and zanamivir, which are neuraminidase inhibitors.
What is H3N2?
H3N2 is a subtype of influenza A virus that contains main surface proteins known as H3 (hemagglutinin3) and N2 (neuraminidase2). H3N2 is also currently endemic in both human and pig populations. This viral subtype first evolved from the H2N2 virus by antigenic shift and caused the Hong Kong pandemic flu 1n 1968 and 1969, which killed approximately 750,000 people. A severe form of this viral subtype circulated among children in the United States in 2003 as well.
H3N2 genome size is around 13628 nucleotides in length (13.628 kb). A dominant and resistant strain of this virus caused the annual flu in 2006. Furthermore, it has been identified that H3N2 has increased its resistance to antiviral medications like amantadine and rimantadine from 1994 to 2005. In addition, the human H3N2 influenza viral subtype is now endemic in pigs in southern China. This human H3N2 viral subtype circulates together with the avian H5N1 viral subtype.
What are the Similarities Between H1N1 and H3N2?
- H1N1 and H3N2 are two subtypes of the influenza A virus.
- Both subtypes belong to the genus Alphainfluenzavirus and the family Orthomyxoviridae.
- They are endemic in humans, pig populations, and birds.
- Both subtypes are controlled by vaccination and antiviral medications.
What is the Difference Between H1N1 and H3N2?
H1N1 is a subtype of influenza A virus that contains main surface proteins known as H1 and N1) while H3N2 is a subtype of influenza A virus that contains main surface proteins known as H3 (hemagglutinin3) and N2 (neuraminidase2). Thus, this is the key difference between H1N1 and H3N2.
The below infographic presents the differences between H1N1 and H3N2 in tabular form for side-by-side comparison.
Summary – H1N1 vs H3N2
Influenza A causes influenza illness in birds, pigs, and mammals, including humans. This virus belongs to the genus Alphainfluenzavirus and the family Orthomyxoviridae. H1N1 and H3N2 are two subtypes of the influenza A virus. H1N1 is a subtype of influenza A virus that has main surface proteins known as H1 (hemagglutinin1) and N1 (neuraminidase1), while H3N2 is a subtype of influenza A virus that has main surface proteins known as H3 (hemagglutinin3) and N2 (neuraminidase2). So, this is the key difference between H1N1 and H3N2.
Reference:
1. “H1N1 Influenza.” Statpearls – NCBI Bookshelf.
2. “Influenza A (H3N2) Variant Virus.” Centers for Disease Control and Prevention.
Image Courtesy:
1. “H1N1 virus” By Manu5 – Scientific Animations (CC BY-SA 4.0) via Commons Wikimedia
2. “Influenza nomenclature” By Burschik – Own work (CC BY-SA 3.0) via Commons Wikimedia