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Flashcards in RNA Virus 2 Deck (27):
1

Rotavirus

-reovirus
-dsRNA
-segmented
-naked icosahedron (round)

2

Influenza Virus

-orthomyxovirus
- neg ss RNA
-segmented
-enveloped

3

HIV

-retrovirus
- + ssRNA, 2 copies
-enveloped

4

rotavirus disease

-causes severe gastroenteritis
-profuse watery diarrhea
-dehydration
-maladsorption
-affects infants and children (adults are usually asymptomatic)
->60,000 deaths annually, mostly in developing world
-peak incidence during winter

5

Rotavirus life cycle

-genome is segmented, one gene each (dsRNA)
-enters by endocytosis
-escapes from early endosome by acidification
-RDRP in the virion first transcribes mRNA
-after viral proteins are translated, new virions and genome segments are synthesized in the cytoplasm
-virions assemble and then bud into the rough ER (displace membrane they get there)
-egress via exocytosis (membrane vesicles carry virions out) or by cell lysis
-virions mature in gut lumen, then infect more enterocytes or are shed in profuse diarrhea

6

rotavirus diagnosis, treatment, prevention

-diagnosis not required in most cases
-trt-oral rehydration solutions
-prevention- live attenuated vaccine-rotarix (1) and rotareq (5)

7

influenza virus disease

-acute respiratory illness, mainly during the winter
-uncomplicated-upper/lower resp tract involvement, fever, headache, myalgia, weakness
-complicated-primary pneumonia caused by flus
-secondary bacteria pneumonia
-mixed viral and bacteria pneumonia
-muscle involvement, myositis, rhabdomyelitis (breakdown)

8

symptoms of flu

-central-headache
-nasopharynx-runny or stuffy nose, sore throat, aches
-resp-coughing
-gastric-vomiting
-joints-aches
-muscular-extreme tiredness
-systemic-fever

9

Influenza life cycle

-genome is segmented, neg ss RNA
-binds via hemagglutin and fuses to endosome, pH change releases genes
-genome segments traffic to the nucleus for transcription and replication by RDRP
-viral proteins and genome segments accumulate at the PM
-virions assemble and egress by budding
-neuraminidase releases virions from sialic acid on cell surface
-shed in resp droplets

10

flu treatment and prevention

-antiviral drugs-tamiflu (A and B)- stops release from PM, Relenza (A and B), Amantadine and Rimantadine-A
-vaccines-fluzone and trivalent inactivated, flu mist
-giving H1N1, H3N2 and B this year

11

antigenic shift

-genetic shuffling makes new versions of A subtype from other subtypes

12

antigentic drift

random mutation- makes new strains from the new A subtype
-can stay for about 10 years

13

acute HIV infection

-systemic-fever, WEIGHTLOSS
-central-MALAISE, NEUROPATHY, headache
-lymph-LYMPHADENOPATHY
-skin-RASH
-gastric-vomiting, nausea
-liver and spleen-ENLARGEMENT
-muscles-myalgia
-esophagus-sores
-pharyngitis-SORES, THRUSH

14

stages of HIV disease

1. exposure to virus
2. primary HIV infection (acute phase)
3. seroconversion
4. latent period
5. early symptomatic HIV infection
6. AIDS- CD4 < 200
7. Advanced HIV infection- CD4 < 50

15

HIV cell tropism

-only humans can be infected
-virus binds to CD4 and chemokine receptors (CCR5) on T cells and macrophages
-depletion of these cells and chronic immune activation cause immunodeficiency

16

HIV R5

-CCR5

17

HIV R5X4

-CCR5 and CXCR4

18

HIV load and CD4 T cells

-initial-most HIV and least T cells
-then T cells recover slightly, HIV drops a little
-then HIV gradually increases while T cells gradually decrease
-as T cells decrease, opportunistic infections increase

19

AIDS and loss of T cells

-bacterial skin infections, shingles, thrush, athletes foot, oral hairy leukoplakia, TB
-then AIDS defining

20

top 10 AIDS defining infections

1. pneumocytis cariniii pneumonia
2. esophageal candidiasis
3. wasting
4. Kaposi's sarcoma
5. disseminated M avium infection
6. TB
7. Cytomegalovirus disease
8. HIV associated dementia
9. recurrent bacterial pneumonia
10. toxoplasmosis

21

main symptoms of AIDS

-neuro-encephalitis/meningitis
-eyes-retinitis
-lungs-pneumocystis pneumonia, TB, tumors
-skin-tumors
-GI-esophagitis, chronic diarrhea, tumors

22

HIV life cycle

-virion fuses with CD4 and CCR5
-fuses with PM- brings in protease, integrase and RT-can hang out there until T cell divides and many nts around
-the RT converts the + ss RNA into dsDNA (hypermutation here)
-the dsDNA genomes integrate into the host chromosome for life
-host RNA pol II transcribes mRNA from the integrated genome, which also serves as the genome that is packaged into the new virions (because its + ss)
-viral proteins and 2 genomes bud from PM
-virion maturation occurs outside the cell when the viral protease cleaves the capsid proteins, forming the final trapezoidal step

23

HIV diagnosis and prevention

-diagnosis-serologic assays for antibodies
-nucleic acid assays for viral load
-CD4 cell count
-prevention- risk avoidance
-community awareness
-public health measures
-antiviral drugs-chemoprophylaxis

24

HIV treatment

-ART
-must be combined to avoid resistance
-new formulations reduce pills and doses increase compliance

25

types of HIV drugsq

-nucleoside reverse transcriptase inhibitors (NRTIs)
-non-nucleoside RT inhibitors (NNRTIs)
-Protease inhibitors (PI)
-integrase strand transfer inhibitors (INSTIs)
-CCR5 agaonists

26

goals of HIV treatment

-durable suppression of HIV viral load
-restoration of immune function
-prevention of transmission
-prevention of drug resistance
-improvement of QOL

27

vaccine?

-more is known about HIV than any other virus, but vaccine remains elusive
-what should it accomplish-sterilizing immunity? no progression to AIDS? no transmission?