ABA inhibits precocious germination and vivipary ABA accumulates in dormant buds ABA inhibits ga-induced enzyme production

TLS Online TPP Program

#Id: 9921

#Unit 4. Cell Communication and Cell Signaling

Cell-Mediated Immunity against Virus

Both CD8+ TC cells and CD4+ TH1 cells are required components of the cell-mediated antiviral defense.

Activated TH1 cells produce IL-2, IFN-ϒ, and tumor necrosis factor-α.

TLS Online TPP Program

#Id: 9922

#Unit 4. Cell Communication and Cell Signaling

IFN-ϒ acts directly by inducing an antiviral state in nearby cells.

IL-2 acts indirectly by assisting the development of cytotoxic T lymphocyte(CTL) precursors into an effector population.

Both IL-2 and IFN-ϒ activate NK cells.

TLS Online TPP Program

#Id: 9923

#Unit 4. Cell Communication and Cell Signaling

TLS Online TPP Program

#Id: 9924

#Unit 4. Cell Communication and Cell Signaling

Viruses Employ Several Different Strategies to Evade Host Defense Mechanisms

Hepatitis C virus, inhibiting the action of PKR.

Herpes simplex virus TAP.

TLS Online TPP Program

#Id: 9925

#Unit 4. Cell Communication and Cell Signaling

Adenoviruses and cytomegalo virus use to reduce the surface expression of class I MHC molecules, 

Measles virus and HIV, reduce levels of class II MHC molecules on the surface, 

Vaccinia virus, secreting a protein that binds to the C4b complement component.

TLS Online TPP Program

#Id: 9926

#Unit 4. Cell Communication and Cell Signaling

Influenza virus

Influenza are surrounded by an outer envelope, a lipid bilayer derived from the plasma membrane of the infected cell.

Viral specific Protein 

Hemagglutinin (HA) 

Neuraminidase (NA)