Viruses I Flashcards Preview

microbio/immunology > Viruses I > Flashcards

Flashcards in Viruses I Deck (36):

Basic viral outcomes in host cells (2)

1. cytolytic:
causes cell lysis of host cell (permanent damage)
2. immunopathology:
present virus peptides (HLA-1) --> immunologically induced cell lysis


polio vaccines

1. 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.
2. 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*


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)
- 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.



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)



+ 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.



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


Protozoa associated with HIV/AIDS infection

(secondary infection bc of immunosuppression)
- toxoplasma gondii
- cryptosporidium parvum
- helminths


types of drugs used for HIV treatment

1. Reverse transcriptase inhibitors
a) nucleoside analogs
b) non-nucleoside cmpds
2. HIV-1 Protease inhibitors (bc viral protease = diff. than human)
3. CCR5 inhibitor (not ideal)
4. fusion inhibitor (injected, not ideal)
5. Integrase inhibitor


8 human Herpes viruses w/ mode of transmission

1, 2. Herpes Simplex (HSV-1, HSV-2) - sex, perinatal
3. varicella zoster (VZV) - aerosol
4. Cytomegalovirus (CMV) - Aerosol, sex/blood
5. Ebstein-Barr virus (EBV) - #1 saliva, sex/blood/perinatal
6, 7. HHV-6, HHV-7 - Saliva, common
8. Kaposi's Sarcoma Herpes Virus (KSHV) - MSM sex


Characteristics of Herpes virus infection

--> life-long, quiescent infections (do NOT clear),
CAN reactivate w/ or w/OUT symptoms (--> spread)

prevent spread: daily acyclovir -- for HSV-1, 2; VZV reactivation


Cytomegalic Inclusion Disease (CID)

Congenital disease caused by cytomegalovirus,
--> microcephaly and mental retardation


Cytomegalovirus-associated conditions

1. congenital birth defects (#1 hearing loss, seizures, IQ deficit)
2. Cytomegalic Inclusion Disease (microcephaly)
3. Mononucleosis -- in transplant recipients
4. Pneumonitits/Chorioretinitis/Dementia (from reactivation) -- in AIDS patients


Sites of latent infection for Herpes viruses

1) HSV and VZV: sensory ganglia
2) CMV: MANY sites (kidney, leukocytes, male reproductive tissue, etc.)
3) EBV: B cells
4) KSHV: Epithelial and B cells



Any rash accompanied by inflammation that is caused by an infectious process
ie: measles, rubella, roseola, ECHO virus


Rubella virus characteristics

Togavirus, Enveloped SS RNA, + polarity.
* full life-cycle needs sub-genomic mRNA*
1 serotype --> vaccine = part of MMR
transmission: aerosol, incubation: 14-21 days


Rubella symptoms

Fever, malaise,
* maculopapular starts on face and spreads to rest of body
(rash comes from viral replication AND immunopathology);
resolves in 2-4 days.


Congenital Rubella Syndrome (CRS)

Major/severe congenital defects associated with maternal rubella infection in 1st trimester,
* worst at earliest stages in pregnancy (ie: 1st month)
--> heart/eye/brain dysfunction, spontaneous abortion, stillbirth


Rabies virus characteristics

negative, SS RNA, enveloped. Replication like measles virus.
* single serotype!
bullet-shaped virion, Rhaabdovirus family
transmission by wild animal bites (in any mammals).