Influenza A Subtypes and the Species Affected

Influenza A viruses are divided into subtypes based on two proteins on the surface of the virus: the hemagglutinin (H) and the neuraminidase (N). There are 18 different hemagglutinin subtypes and 11 different neuraminidase subtypes. All known subtypes of influenza A viruses have been found among birds, except subtype H17N10 and H18N11 which have only been found in bats. Below is a table showing the different hemagglutinin and neuraminidase subtypes and the species in which they have been detected.

Hemagglutinin

Table. Different hemagglutinin subtypes and the species in which they have been detected.
Subtype People Poultry Swine Bats Cats Dogs Horses Cows Other*
H1 X
H2
H3 X
H4 X
H5 ** X
H6
H7 X
H8
H9
H10 X
H11
H12
H13
H14
H15
H16
H17
H18

*These include seals, ferrets, minks, tigers, leopards, and polar bears, among others.

**Highly pathogenic avian influenza A(H5N1) viruses were first detected in pigs in Fujian Province, southern China in 2001. These infections in pigs in China – and, later, elsewhere in Asia — were caused by different A(H5N1) viruses than those that have caused outbreaks in wild birds, poultry, dairy cows, and other animals in the United States.

Neuraminidase

Table. Different neuraminidase subtypes and the species in which they have been detected.
Subtype People Poultry Swine Bats Cats Dogs Horses Cows Other
N1 X
N2 X
N3
N4
N5 X
N6
N7 X
N8 X
N9
N10
N11