University:
University of Central Lancashire
Course:
UM2010 | Medicine 1
Academic year:

2024
Views:

158

Pages:

3
Author:

Juwairiah N

Lec 5 - Viruses Smallest infectious agent (20 to 300nm). Cannot be seen under a light microscope, only visible using TEM and SEM. Smallpox is caused by airborne Variola major and Variola minor. In survivors it can cause disfigurement and blindness. Eradicated through vaccines. Influenza is caused by RNA viruses in the family Orthomyxoviridae. Spanish flu pandemic in 1918. AIDS (acquired immune deficiency syndrome) is caused by HIV, a virus which kills T-cells. Can live with AIDS using anti-retroviral drugs, which can reduce contagiousness and transmission of HIV. HBV (Hepatitis B virus) causes illness of the liver. Transmitted by exposure to infectious blood or body fluid. HBV is 50 to 100 times more infectious than HIV. The infection can be acute or chronic. SARS (severe acute respiratory syndrome) is caused by SARS coronavirus. STRUCTURES: Helical Nucleocapsids are single- or double-stranded DNA or RNA, surrounded by capsomeres which make up a capsid. This is then surrounded by a fat+protein envelope. Eg- tobacco mosaic virus. Icosahedron have 12 vertices, and 30 edges. May have 5, 3 or 2 rotational axes. Eg- adenovirus, which causes the common cold. CLASSIFICATION: this is firstly based on the genome type (DNA or RNA), and by other characteristics such as if it is enveloped or naked. DNA FAMILY 1: Adenovirus more than 50 variants that infect humans causes wide range of infections from mild to lethal diseases. DNA FAMILY 2: Herpesviridae Herpes simplex 1 and 2 Double-stranded DNA Lays dormant in the body (latent virus) until triggered Watery blisters in the skin or mucous membranes of the mouth, lips or genitals DNA FAMILY 3: Poxviridae Causes pox viruses Variola major and minor are smallpox, Varicella is chicken pox. RNA FAMILY 1: Reoviridae aka Rotavirus Causes severe diarrhoea in children, but most cases of infection are mild Reoviruses have oncolytic (cancer-killing) properties, encouraging the development of reovirus-based therapies for cancer. RNA FAMILY 2: Picornaviridae Includes polio virus, hepatovirus (hepatitis), coxsackie virus, and rhinovirus (common cold). Polio is highly infectious and invades the nervous system and can cause paralysis within hours. RNA FAMILY 3: Rhabdoviridae Rabies virus causes rabies fatal encephalitis. RNA FAMILY 4: Paramyxoviridae Paramyxovirus includes parainfluenza and mumps viruses Pneumovirus includes RSV, a respiratory virus Morbillivirus includes the measles virus Family Retroviruses include HIV 1 and 2.