Arising in the mucous membranes, these white patches on the tongue, gums, cheeks, or elsewhere inside the mouth have the potential to develop into squamous cell carcinoma. They may be caused by sources of chronic irritation, such as habitual alcohol consumption or tobacco use, or rough edges on teeth or dentures.
Virus infection in vertebrates results in two general types of immune response. The first is a rapid-onset innate response against the virus, which involves the synthesis of proteins called interferons and the stimulation of natural killer lymphocytes.
Although most viral infections result in a protective response from the immune system, viruses such as HIV specialize in evading the immune system by using a number of different techniques. Neurotropic viruses are also very capable of avoiding our natural immune system's response to infection.