A true pilonidal sinus in the hand of a sheep shearer. 2) Uncommonly, the cyst may become secondarily infected, resulting in osteomyelitis with formation of an abscess and draining sinus to the overlying skin. Echinococcal disease of the bone: an unusual cause of a pathological fracture.
Tobacco mosaic virus (TMV) is a positive-sense single stranded RNA virus that infects a wide range of plants, especially tobacco and other members of the family Solanaceae.The infection causes characteristic patterns, such as  mosaic -like mottling and discoloration on the leaves (hence the name).TMV was the first virus ever to be discovered.Although it was known from the late 19th century that an infectious disease was damaging tobacco crops, it was not until 1930 that the infectious agent was determined to be a virus.he infection causes characteristic patterns, such as  mosaic -like mottling and discoloration on the leaves (hence the name). TMV was the first virus ever to be discovered.
A type of virus that has RNA instead of DNA as its genetic material. It uses an enzyme called reverse transcriptase to become part of the host cells' DNA. This allows many copies of the virus to be made in the host cells. The virus that causes AIDS, the human immunodeficiency virus (HIV), is a type of retrovirus.hen a retrovirus infects a cell, it makes a DNA copy of its genome that is inserted into the DNA of the host cell. There are a variety of different retroviruses that cause human diseases, including the common cold, some forms of cancer, and AIDS.