The most important of them are 

Genetic Diversity

Species Diversity 

Ecological diversity

TLS Online TPP Program

#Id: 9928

#Unit 4. Cell Communication and Cell Signaling

There are 18 different antigenic subtypes for HA and 11 for NA.

TLS Online TPP Program

#Id: 9929

#Unit 4. Cell Communication and Cell Signaling

TLS Online TPP Program

#Id: 9930

#Unit 4. Cell Communication and Cell Signaling

Variation in Influenza Strains

Antigenic variation in HA and NA is generated by

Antigenic drift involves a series of spontaneous point mutations that occur gradually.

Antigenic shift results in the sudden emergence of a new subtype of influenza.

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#Id: 9931

#Unit 4. Cell Communication and Cell Signaling

Original antigenic sin

Tendency to focus an immune attack on those structures that were present during the original.

This means that our immune systems effectively ignore the subtle changes occurring each year in pathogens

TLS Online TPP Program

#Id: 9932

#Unit 4. Cell Communication and Cell Signaling

TLS Online TPP Program

#Id: 9933

#Unit 4. Cell Communication and Cell Signaling

Bacterial Infections

Bacteria enter the body through several natural routes.