Human diseases - Viruses and Prions

proteinaceous infectious particles that cause disease

family of rare progressive neurodegenerative disorders that affect humans and animals

• long incubation periods
• cause spongiform changes associated with neuronal loss
• rapidly progressive and always fatal

creutzfeld jakob disease and kuru

scrapie in sheep and mad cow disease in cattle

• protein misfolding that occurs spontaneously
• eating meat that is contaminated with brain material with misfolded proteins

10-400nm

acellular

a protein coat

DNA or RNA

a complete viral particle of nucleic acid and protein coat

about 10% of the human genome is comprised of genetic information from viruses

pieces of DNA(virus like) that make copies of themselves

viral genetic information can be included in the genome when retroviruses incorporates into the host's germ line

• capsid symmetry
• nucleic acid
• genetic relatedness

• airborne
• arthropod borne
• direct contact
• food and water borne

• chickenpox/shingles
• measles
• mumps
• rubella
• smallpox
• influenza

• large brick shaped complex virus
• linear dsDNA

• negative sense RNA
• disease of the respiratory system
• high frequency of genetic changes

1-2 days

based on hemagglutinin (HA) and neuraminidase (NA) membrane surface glycoproteins

due to reassortment of genomes when 2 different strains of flue viruses from humans and animals infect the same cell and are incorporated into a single new capsid

• due to accumulation of mutaions in a strain within a geographic area
• often the result of point mutations that lead to amino acid substitutions

• positive sense ssRNA virus
• enveloped retrovirus: RNA genome is copied into DNA and integrated into the host cell genome
• mutates rapidly

the retrovirus undergoes reverse transcription to generate DNA from RNA. The DNA is then integrated into the host genome as a provirus

virus genome that is integrated into the DNA of a host cell