Adenovirus infected 293T cell, coloured scanning electron micrograph (SEM). The virus is internal and not visible here. The cell shows early apoptotic changes. 293T cells have lost the capacity to defend themselves from viral infection, a capability in which all cells normally excel. 293T express several viral proteins that switch cellular defences off allowing researchers to introduce DNA (deoxyribonucleic acid) and use the cells to make large amounts of protein, or infectious viruses. Adenoviruses are common causes of respiratory illness, but most infections are not severe. They can cause cold-like symptoms, sore throat, bronchitis, pneumonia, diarrhoea, and conjunctivitis. It is contactable at any age, but infants and people with weakened immune systems are more likely than others to develop severe illness. Magnification: x3000 when printed at 10cm wide. Specimen courtesy of Greg Towers, UCL, UK. |