Frizzled-G protein signaling activates PLC-beta, which cleaves PIP2 into DAG and IP3.

TLS Online TPP Program

#Id: 9927

#Unit 4. Cell Communication and Cell Signaling

HA trimers are responsible for the attachment of the virus to host cells, binding to the sialic acid. 

NA is an enzyme that cleaves N-acetyl neuraminic (sialic) acid

Within the envelope, consists of eight different strands of single- stranded RNA (ssRNA) associated with protein and RNA polymerase. 

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.

TLS Online TPP Program

#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