Transcript Common cold viruses

Viruses and Prions
RNA Viruses
Picornaviruses
• Poliomyelitis
– Fecal-oral and pharyngeal transmission
– Attacks NS and can cause paralysis
– Vaccine has nearly eradicated the disease in US.
• Hepatitis A
– Fecal oral transmission, often through contaminated food
• Enteroviruses cause a variety of diseases including, febrile
illnesses, and acute hemorrhagic conjunctivitis, GI diseases
• Rhinoviruses- common colds
Viruses that cause GI diseases
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Rotaviruses (Reoviridae)
Caliciviruses
Norwalk virus
Norwalk-like viruses
Coronavirus
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SARS (Severe acute respiratory syndrome
– first reported in Asia in February 2003.
– In 2003, a total of 8,098 people worldwide became
sick with SARS; of these, 774 died
– High fever, headache, myalgia, dry cough, pneumonia
– Spread by close contact
• Common cold viruses
Bunyaviruses
• Hantavirus Pulmonary Syndrome (HPS)
– Rodents are reservoir
– Virus airborne from rodent feces
• Viral encephalitis
• Crimean Congo Hemorrhagic Fever (CCHF)
– Vector borne zoonosis
Togaviruses
• Rubella (German measels)-produces flat pink rash
usually mild, but congenital rubella syndrome can
cause sever abnormalities in babies
• Arboviral Encephalitis viruses -Equine encephalitis
– EEE (most severe)
– WEE
– VEE
Orthomyxoviruses: Influenza
• A variety of types (A, B, and C) infect many birds and
mammals
• Type A can infect humans and cause pandemics
• Transmembrane proteins Hemagglutinin and
Neuraminidase mediate viral attachment and entry
• Mutations cause antigenic drift which results in frequent
changes of HA
• Genetic reassortments between different Influenza
viruses result in antigenic shift
Pandemic
Strain
Antigenic
shifts
Avian
viruses
Antigenic
shifts
Paramyxoviruses
• Respiratory Syncitial Virus
– Children under 1 most severely affected
– Common, mild in adults
• Mumps- swellings of oral cavity
• Measels (rubeolla)- produces raised red rash
• Parainfluenza-croup
Arboviral flaviviruses
• West Nile Fever
– Emerging disease in US
– Relatively mild
– Infects many birds and mammals
– Culex spp. are vectors
• St. Louis encephalitis (SLE)
• Yellow fever- monkeys are reservoir
• Dengue fever and DHF (breakbone fever)
Hepatitis C virus
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Flaviviridae family
Hepacivirus genus
Causes liver disease and cancer
Transmitted through blood, IV drugs, body piercing,
tattoos
Rabies Virus
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Transmitted by bite of infected mammals
Virus migrates from PNS to CNS
Inclusion bodies (Negri bodies) found in brain tissue
IFAT of brain tissue
Infects most mammals, susceptibility varies and is
correlated with maintenance
• Slow incubation allows for post-infection vaccination
HIV human Immunodeficiency Virus
(Retroviridae)
• Viral properties
– Envelope
– Protein coat
– Complex RNA genome
– RT and integrase enzymes
• Infection, dissemination through lymphoid organs,
clinical latency, expression of HIV, clinical disease, and
death
• Progressive antigenic variation in response to host’s
immune system
• CD4 T cell depletion leads to immunodeficiency
DNA viruses
Herpesviruses
• Herpesviridae contains several important agents of
human disease and NOT all of them are sexually
transmitted
• HSV-1 and HSV-2
• Varicella-Zoster
• Epstein-Barr virus (EBV)
Herpes simplex viruses
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HSV-1 fever blisters
HSV-2 genital herpes
Both viruses can cause either symptoms
Permanent infections, remain latent in spinal nerves and
erupt into lesions at original site of infection
• Lesions are progressively less severe
Chicken pox and Shingles
vericella-zoster virus
• Chicken pox (vericella)
– virus enters through mucus membranes
– Skin lesions appear after 2 weeks starting on scalp
and trunk and moving to other epithelial sites
including respiratory, digestive tract or vagina
– Remain in spinal nerves for decades
• Shingles (zoster)- eruption of latent virus from peripheral
nerves to dermatomes
Pox viruses
• Small pox (variola virus)– Enters throat and resp. tract
– Infects phagcytic cells and blood cells
– Pus-filled vesicles form in mouth and throat then face,
forearms, hands
• Cow pox (vaccinia), monkeypox viruses– less severe than small pox
– antibodies cross reactive with small pox
• Molluscum Contagiosum Virus– causes painless pearly white tumors –
– increasing as an STD can can become inflamed
around genitals
Warts (Papillomas)
Papovaviridae
• HPV- human papilloma viruses
– Transmitted by direct contact or fomites
– Many different types that can infect a variety of
locations including skin, genital, respiratory tracts
– Virus infection lasts a lifetime
– Can be malignant
– Cervical cancer-99% of cases linked to HPV
– Warts may be most problematic in
immunocompromised
– Warts not always present
Hepatitis B virus
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Hepadnaviridae
One of the most common blood borne pathogens
Causes liver diseases and cancer
Transmitted through blood and sex
Vertical transmission from mother to baby
Prion Diseases
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Mad Cow Disease (BSE)
Scrapie
vCJD
Kuru
Prions
Infectious proteins
Normally found on surface of mammalian
cells
Abnormal secondary and tertiary structures
Resistant to heat and radiation
Long ‘incubation’ period
Prion “replication”
Normal protein transformed from helices to beta
pleated sheets
BSE