Populations grow when R0 or λ>1, populations decline when R0 or λ<1, and are at equilibrium when R0 or λ=1

TLS Online TPP Program

#Id: 9930

#XL - T Zoology

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

#XL - T Zoology

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

#XL - T Zoology

TLS Online TPP Program

#Id: 9933

#XL - T Zoology

Bacterial Infections

Bacteria enter the body through several natural routes.

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#Id: 9934

#XL - T Zoology

Cell wall endotoxins of some gram-negative bacteria activate macrophages, resulting in release of high levels of IL-1 and TNF-α, which can cause septic shock.

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#Id: 9935

#XL - T Zoology

In staphylococcal food poisoning and toxic shock syndrome, exotoxins produced by the pathogens function as superantigens, which can activate all T cells.