Apoptosis is a regulated, energy-dependent process by which a cell se- destructs. This mechanism of programmed cell death plays an important role in normal development and control of cell numbers in mature a- mals. Apoptosis was initially defined by morphological criteria to describe the distinctive appearance of dying cells that developed nuclear conden- tion, cell shrinkage, and cytoplasmic blebbing. Initiation of the apoptotic process can come from external or internal stimuli and is highly regulated both by molecules that facilitate and by molecules that inhibit the process. Common features of apoptosis include activation of proteases and - cleases, mitochondrial membrane permeabilization, chromatin disruption, and translocation of phosphatidylserine from the inner to the outer s- face of the plasma membrane. Apoptotic cells attract phagocytes that - gulf the apoptotic bodies and prevent tissue damage in the region. Intense investigation of the cell death process has defined many molecular features of the pathway by which regulation and execution can be exploited by pathogens.

Measles virus, one of the most contagious of all human viruses, has been largely contained by the development and use of a vaccine that was introduced 50 years ago. These two volumes were timed to honor the introduction of the vaccine and to record the enormous advancements made in understanding the molecular and cell biology, pathogenesis, and control of this infectious disease. Where vaccine has been effectively delivered, endemic measles virus transmission has been eliminated. However, difficulties in vaccine delivery, lack of health care support and objection to vaccination in some communities continue to result in nearly 40 million cases and over 300,000 deaths per year from measles.

By itself measles virus infection has and still provides some of the most interesting phenomena in biology. Following infection of dendritic cells, measles virus causes a profound suppression of the host s immune response that lasts a number of months after apparent recovery from infection. Indeed, measles virus was the first virus to be associated with immunosuppression with many of the manifestations to be observed one hundred years later with HIV infection. Measles is also associated with development of both post-infectious encephalomyelitis, an autoimmune demyelinating disease, and subacute sclerosing panencephalitis, a slowly progressive neurodegenerative disorder. How measles virus infects cells, spreads to various tissues and causes disease, as well as the role of the immune response, generation of new vaccines, and use as a vector for gene delivery are topics covered in these two volumes. "

Apoptosis is a regulated, energy-dependent process by which a cell se- destructs. This mechanism of programmed cell death plays an important role in normal development and control of cell numbers in mature a- mals. Apoptosis was initially defined by morphological criteria to describe the distinctive appearance of dying cells that developed nuclear conden- tion, cell shrinkage, and cytoplasmic blebbing. Initiation of the apoptotic process can come from external or internal stimuli and is highly regulated both by molecules that facilitate and by molecules that inhibit the process. Common features of apoptosis include activation of proteases and - cleases, mitochondrial membrane permeabilization, chromatin disruption, and translocation of phosphatidylserine from the inner to the outer s- face of the plasma membrane. Apoptotic cells attract phagocytes that - gulf the apoptotic bodies and prevent tissue damage in the region. Intense investigation of the cell death process has defined many molecular features of the pathway by which regulation and execution can be exploited by pathogens.