Cytosis (leuco/cyt/osis; thrombo/cyt/osis) means:

Cytosis normally is a mode of movement where large amount of molecules move out or in the cell. There are mainly three types endocytosis, exocytosis and transcytosis. On the other hand, leucocytosis (from leucocytes- white blood cells) is a condition caused by increase in the number of white blood cells. The condition may be caused by infections such as TB and also some form of cancer. Thrombocytosis similarly is a condition where the body produces too many platelets (helps in blood clotting).

When a virus infects a host cell, it uses the cell's machinery to make copies of its own genetic material in a process called replication. finally, during the process of self-assembly, that protein shell and the copies of the virus's genetic material are assembled into new viruses.