type A, B & C
The worst swam flu _____ more in children
what are the 2 characterstics of Flu virous
1. Antigenic draft natural mutation
2. Antigenic shift
H1N1 swine flu
The main cause of death was viral pneumonia with resulting ARDS (Adult Respiratory Distress Syndrome). Even though treated in a hospital ICU, approximately 50% of ARDS cases result in death.
what are the 2 type of flue viruse
N affect upper repirtoary systme distroy the mucosue to reach the cell.
H viruse recongintion
HIV use T cells
Key to influenza are ___
15 different subtypes; most important virulence factor; binds to host cells. H spikes are need for the viral entry.
*9 subtypes - hydrolyzes mucus
*N spikes help with the mobility of the virus thru the respiratory mucus& assist viral budding and viral release.
Constant mutation is called___gradually change their amino acid composition
one of the genes or RNA strands is substituted with a gene or strand from another influenza virus from a different animal host
Not known to undergo antigenic shift
Known to cause only minor respiratory disease; probably not involved in epidemics
type A undergoes antigenic shift but types B & C do not undergo antigenic shift. This is perhaps because they (B &C) only infect human and not other animals
*Seasonal, pandemics; among top 10 causes of death in U.S.- most commonly among elderly and small children
*Weakened host defenses predispose patients to secondary bacterial infections, especially pneumonia
*Oseltamivir (Tamiflu) is a prodrug and works against fluA. Mode of action inhibits neuraminidase.
Zanamivir (Relenza): inhibits NA. Tamiflu and Relenza work best against H1N1 when given early in infection.
Amantidine: An older drug to treat flu A & B.
*an older drug to treat flu A & B
H1N1 is 100% resistant to__
H1N1 is a____meaning can be transferred from animals to human.
control symptoms; amantadine, rimantadine, zanamivir (Relenza) and oseltamivir (Tamiflu)
*Flu virus has developed high rate of resistance to amantadine and rimantadine
*Annual trivalent vaccine recommended. It is made up of the inactivated 2 type A and 1 type B strains of the flu virus
caused by a variety of parasites, bacteria, and viruses. eg. E. coli. A common viral cause is Norovirus. Noroviruses are a genetic diverse group of nonenveloped ss RNA viruses.
Bunyaviruses and Arenaviruses
Transmitted zoonotically; cause periodic epidemics; extremely dangerous; biosafety level 4 viruses
(-) strand RNA viruses. transmitted by insects and ticks. They are vector-borne viruses. Hantavirus vector is rodent
transmitted to human by rodents. Transmission through aerosols and contact
Lassa fever (a hemorrhagic fever), Argentine hemorrhagic fever, Bolivian hemorrhagic fever, and Lymphocytic chroiomeningitis
Biosafety level 4 lab
___needed for bunyaviruses & arenaviruses
parainfluenza, mumps virus
Morbillivirus (measles virus)
Cause mumps, measles, and Pnuemonovirus also called viral pneumonia (respiratory syncytia virus) & bronchitis in children. In adults, cuz mild upper respiratory infections
are (-) sense RNA viruses w a helical shape nucleocapsid.
Envelope has HN (for cell attachment) and specialized F spikes that initiate cell-to-cell fusion.
F spike casuses fusion with neighboring cells - syncytium or multinucleate giant cells form.
*Seen mostly in children
*Minor cold, bronchitis, bronchopneumonia
*Antiinflammatory steroids (i.e, dexamethasone) used for treatment
* Epidemic parotitis; self-limited, associated with painful swelling of parotid salivary glands
Humans are the only reservoir.
*40% of infections are subclinical; long-term immunity.
*Incubation 2-3 weeks w fever, muscle pain and malaise, classic swelling of one or both cheeks
*Caused by Morbillivirus (SSRNA envelop virus, a member of paramyxoviruses).
*Also known as red measles and rubeola.
*Different from German measles (rubella)
*Very contagious; transmitted by respiratory aerosols
Humans are the only reservoir
*Virus invades respiratory tract
*Koplik spots which are oral lesions (viral prodrome)
Most serious complication is subacute sclerosing panencephalitis (SSPE), a progressive neurological degeneration of the cerebral cortex, white matter and brain stem.
SSPE characterized by a history of primary measles infection usually before the age of 2 years, followed by several asymptomatic years (6-15 on average), and then gradual, progressive psychoneurological deterioration, consisting of personality change, seizures, Leads to coma and death in months or years
Respiratory Syncytial Virus (RSV) (Pneumovirus)
*RSV is the most common cuz of bronchiolitis (small airways) in young children
*Causes fever, rhinitis, wheezing, otitis, croup (Inflammation of the larynx and trachea)
*Treatment synagis( plivizumab) a monoclonal Ab targeting the fusion protein of the RSV, thus blocks its entry into the cell. Ribavirin.
*carry their genetic material in the form of negative-sense single-stranded RNA.
carry genes for five proteins
large protein (L), glycoprotein (G), nucleoprotein (N), phosphoprotein (P), and matrix protein (M).
*infect vertebrates are bullet-shaped. Enveloped, bullet-shaped virions
*Slow, progressive zoonotic disease
^Primary reservoirs are wild mammals
*spread by both wild and domestic mammals by bites, scratches, and inhalation of droplets
the only rhabdovirus that infects humans zononotic disease characterized by tatal meningoencephalitis.
Clinical phases of rabies
1)Prodromal (early symptoms of a disease)phase - fever, nausea, vomiting, headache, fatigue; pain, burning, tingling sensations at site of wound
2)Furious phase - agitation, disorientation, seizures, twitching, hydrophobia
3)Dumb phase - paralyzed, disoriented, stuporous (lack of consciousness & unresponsiveness)
4)Progress to coma phase, resulting in death
*97% of the bites come from dogs infected w rabies
*most cases in US come from the raccoon or bat bites
*As the disease progresses, more specific symptoms appear and may include insomnia, anxiety, confusion, slight or partial paralysis, excitation, hallucinations, agitation, hypersalivation
*Death usually occurs within days of the onset of these symptoms
*virus travels from the peripheral nervous system to CNS. Once it is in CNS it is incurable
Treatment of rabies
vaccine (inactived virus) can be given pre-exposure to people who are at risks, i.e, veterinarians
For post-exposure, it is often used in conjunction with rabies immunoglobulins as it takes about 7-10 days for the specific antibodies to develop
Definite diagnosis of rabies is __,
are enveloped viruses with a positive-sense single-stranded RNA genome and a helical symmetry.
*infect the upper respiratory and gastrointestinal tract of mammals and birds. They cuz a large # of common colds in human.
* Severe Acute respirtoaty syndrome (SARS)
Rubella (German measles)
*by Rubivirus, a Togavirus
*ssRNA with a loose envelope
* Only complications when effecting pregnant woman as it can adversely effect the embryo.
Two clinical forms of Rubella
Attenuated viral vaccine MMR
Hepatitis C Virus (HCV)
*Flavivirus; Hepatitis C formerly called non-A non-B hepatitis virus
*Acquired through blood contact - blood transfusions, needle sharing by drug abusers
*severe symptoms without permanent liver damage; more common to have chronic liver disease, without overt symptoms. ( patients is asymptomatic but once established, fibrosis of liver can happen)
*Cancer may also result from chronic HCV infection.
*Treatment with interferon and ribavirin to lessen liver damage; no cure & no vaccine yet.
*Viruses Spread by Arthropod Vectors
*life cycles are closely tied to the ecology of the vectors
Causative Agent (HIV) (pathogen that couse diseases)
Retrovirus, genus Lentivirus
HIV can only infect host cells that have the required CD4 marker plus a coreceptor.
Primary effects of HIV infection
extreme leukopenia - lymphocytes in particular
formation of giant T cells and other syncytia allowing the virus to spread directly from cell to cell
Infected macrophages release the virus in central nervous system, with toxic effect, inflammation
Secondary effects of HIV
Destruction on CD4 lymphocytes allows for opportunistic infections and malignancies
Signs & Symptoms of HIV Infections &AIDS
HIV are directly related to viral blood level and level of T cells.
Antibodies are detectable 8-16 weeks after infection.
When T4 cell levels fall below 200/mL AIDS symptoms fever, swollen lymph nodes, diarrhea, weight loss, neurological symptoms, opportunistic infections and cancers.
Diagnosis of HIV Infection
Testing based on detection of antibodies specific to the virus in serum or other fluids; done at 2 levels
ELISA, latex agglutination and rapid antibody tests
rapid results but may result in false positives
Diagnosis of AIDS is made when a person meets the criteria
1. Positive for the virus, and
2. They fulfill one of the additional criteria:
They have a CD4 count of fewer than 200 cells/ul of blood.
Their CD4 cells account for fewer than14% of all lymphocytes.
They experience one or more of a CDC-provided list of AIDS-defining illnesses.
Chemokine receptor type 5 (CCR5) is a protein on the surface of the human white blood cells that many forms of HIV are using as a coreceptor to enter the human cells. People who have a mutation in CCR5 known as CCR5 delta 32 are resistant to HIV infection. The story of Berlin patient.
is a malignant disease of the white blood cell forming elements in bone marrow; bruising or bleeding, paleness, fatigue and recurring minor infections occur
2 leukemias are thought to be viral
Adult T-Cell leukemia - HTLV-I; signs also include cutaneous T-cell lymphoma with lymphadenopathy and dissemination of the tumors to other organs
Hairy-cell leukemia - HTLV II; rare form of cancer; fine cytoplasmic projections that resemble hairs
Enterovirus - poliovirus, HAV
Rhinovirus - rhinovirus
Norwalk agent (Norovirus) - common cause of viral gastroenteritis (cruise ships)
acute enteroviral infection of the spinal cord that can cause neuromuscular paralysis
eradication is expected
is largely supportive for pain and suffering; respiratory failure may require artificial ventilation; physical therapy may be needed.
Prevention is vaccination.
Inactivated polio vaccine (IPV) Salk vaccine
Oral polio vaccine (OPV) Sabin vaccine, attenuated virus - no longer recommended in the U.S.
Worldwide eradication anticipated by 2008
*Coxsackieviruses A and B
Hepatitis A Virus and Infectious Hepatitis
Pooled immune serum globulin for those entering into endemic areas
Human Rhinovirus (HRV)
associated with the common cold
Endemic with many strains circulating in the population at one time; acquired from contaminated hands and fomites
cause 1/3rd of all viral gastroenteritis cases
Acute onset, nausea, vomiting, cramps, diarrhea, chills
Rapid and complete recovery
Creutzfeldt-Jakob Disease (CJD) - alteration in the structure of normal PrP protein found in the brain; change in shape enables the spontaneous conversion of normal PrP creating an accumulation of abnormal PrP that results in nerve cell death, spongiform damage, and severe loss of brain function
Transmission is through direct or indirect contact with infected brain tissue or CSF
proteinaceous infectious particles; highly resistant to chemicals, radiation, and heat
Cause transmissible spongiform encephalopathies (TSEs) in humans and animals
Neurodegenerative diseases with long incubation periods; slow growing disease.
appear 2 days before the rash
Koplike spots are prodrmic
Example of measles
endocytosis into T4
RNA uses it Reverse transcriptase to make a DNA copy 1) one set of RNA carries HIV gentic infromation
2) the othr sets of RNA makes viral parts
Polio transmitted by
Polioviruses adhere to receptors of mucosal cells in oropharynx and intestine, multiply in number and shed in throat and feces, some leak into blood