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.

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Lateral meristem

They are cylindrical meristems

Examples of lateral meristems- vascular cambium and cork-cambium

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Vascular Cambium

The meristematic layer that is responsible for cutting off vascular tissues – xylem and pholem – is called vascular cambium

young stem it is present in patches as a single layer between the xylem and phloem. Later it forms a complete ring

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Formation of cambial ring

The cells of medullary rays, adjoining these intrafascicular cambium become meristematic and form the interfascicular cambium. Thus, a continuous ring of cambium is formed

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Activity of the cambial ring

Cambial ring becomes active and begins to cut off new cells, these cut off cells towards pith, mature into secondary xylem and the cells cut off towards periphery mature into secondary phloem

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