Viruses I Flashcards
(36 cards)
Basic viral outcomes in host cells (2)
- cytolytic:
causes cell lysis of host cell (permanent damage) - immunopathology:
present virus peptides (HLA-1) –> immunologically induced cell lysis
polio vaccines
- IPV - (chemically) Inactivated Polio Virus vaccine, by injection.
- use ONLY IPV in USA. No replication – need 3 doses.
NO spread, does not block fecal-oral spread.
- use ONLY IPV in USA. No replication – need 3 doses.
- OPV - Oral Polio Virus vaccine (live, attenuated virus), by dropper bottle.
Does replicate - single dose = effective.- Excretion of live virus soon after vaccination.
==> both induce humoral immunity for serotypes 1 and 3 (not 2),
(antibodies that intercept polio before clinical disease occurs)
* given at age: 2 months - 6 years*
- Excretion of live virus soon after vaccination.
Polio virus (PV) characteristics
small, non-enveloped icosahedral virus; + polarity, SS RNA;
* cytolytic infection*
humans = only natural host, 3 serotypes.
preferentially replicate in anterior horn of spinal cord
(damages motor neurons)
Polio virus replication process
Host ribosomes immediately translate viral RNA…
–> a) protein intermediate that allows further translation (more mRNA) AND b) viral RNA replication (at same time)
Requires:
- full-length complementary strand RNA
- PV-encoded RNA polymerase;
–> multiple virus populations w/ distinct sequences.
Polio virus clinical presentation
transmission: fecal-oral
Disease states:
- abortive ppoliomyelitis: mild febrile illness
- nonparalytic poliomyelitis: aseptic meningitis (self-resolving)
- paralytic poliomyelitis: flaccid paralysis (permanent motor damage)
Post-Polio Syndrome
Secondary effects of polio, appear 40-60 years after initial infection; (affects 50% of polio patients)
==> neurological condition of fatigue + renewed weakness in originally affected muscles
* mech. unknown
Measles virus characteristics
negative polarity SS RNA, enveloped;
single serotype “paramyxovirus”;
* characteristic surface spikes (hemagglutinin and fusion/hemolytic)
Respiratory Syncytium Virus (RSV) characteristics
a paramyxovirus, structure and function similar to measles (but not hemagglutinin);
Replication: same as measles.
* antiviral Ab targets fusion proteins*
Respiratory Syncytium Virus Infection
–> Bronchiolitis (w/ mucosal necrosis); otitis media, or pneumonia (in elderly)
1-4 day incubation, 10-14 day acute illness
– wheezing, cough, respiratory distress, +/- fever
* mostly in young children, can be fatal in neonates
** prophylactic treatment w/ Ribavirin (inhibits viral RNA replication)
Parainfluenza Virus
4 serotypes, a paramyxovirus;
structurally/functionally similar to measles.
==> croup (narrowing of airway –> “barking”/hoarseness)
* mostly in very young children
Human Metapneumovirus (hMPV)
paramyxovirus, similar to measles;
==> severe bronchiolitis or pneumonia in young or elderly
OR common cold in others.
Rhinovirus
picornavirus (similar structure, f(x), replication to polio virus),
>100 serotypes (very difficult to treat/vaccinate!);
==> #1 for common cold
* optimal temp for replication: 33C (Not GI)
Coronavirus
+ polarity SS RNA, enveloped, multiple serotypes.
==> common cold / lower resp. tract infections
** SARS (Severe Acute Respiratory Syndrome)**
60% case fatality rate
SARS (Severe Acute Respiratory Syndrome)
Respiratory and GI symptoms (cough, SOB, Dyspnia, rapid decline)
- aerosol transmission w/ close contact
4-7 day incubation, HIGH fatality rate.
Hantavirus
aerosol transmission (rodent excretion, NO human-human).
- -> Korean Hemorrhagic Fever - cough, fever, acute renal failure, 5-10% mortality
- -> Hantavirus Pulmonary Syndrome - fever, myalgia, headache, cough, edema, interstitial inflammatory infiltrates – hypoxia
- 60% mortality!
Hendra and Nipah viruses
aerosol transmission,
==> high fever and encephalitis
- hendra: Australia (from fruit bats)
- Nipah: Malaysia (in pigs and people)
influenza virus
Neg. polarity SS RNA, 8 segments (need all 8)
From aquatic birds –> pigs, people;
* 2 genetic phenomenon:
- antigenic drift and shift
Antigenic Shift
major change in viral genome from reassortment of gene segments from mixed infection (by 2+ influenza viruses w/ ~unique genomes)
flow of genetic material for retroviruses
RNA –> DNA –> RNA –> Protein
* uses reverse transcriptase (“RT”)
= RNA(or DNA)-dependent DNA polymerase
Retrovirus Virion genome
2 identical SS RNA, + polarity, enveloped.
* virion RNAs are NEVER translated (into protein)
(–> used to make cDNA by Reverse transcriptase)
diagnostic signs of ATL (Adult T cell Leukemia)
- unusual “flower” cell forms
- aberrant proliferation of T cells
(CD4:CD8 ratio MUCH higher than normal, ie: 5-10) - Cutaneous lymphoma (“mycosis fungoides”)
Viruses associated with HIV/AIDS infection
(= secondary infections bc immunocompromised)
- herpes simplex virus 1 and 2; herpes virus
- cytomegalovirus
- varicella zoster virus
- epstein barr virus
- Kaposi’s sarcoma (skin tumors)
Fungi associated with HIV/AIDS infection
(= secondary infection, bc immunocompromised)
- Candida albicans –> thrush
- pneumocystis jiroveci –> “PCP” severe pneumonia
- cryptococcus neoformans
- aspergillus
- coccidiodes immitus (liver)
- histoplasma capsulatum (macrophages in liver)
Bacteria associated with HIV/AIDS infection
(secondary infection bc of immunosuppresion)
- mycobacterium tuberculosis, avium
- salmonella
- streptococci
- staphylococci
- haemophilus influenzae
