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Microbiology > Lecture 17 > Flashcards

Lecture 17 Flashcards

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1
Q

What three virion enzymes does HIV carry?

A

Reverse transcriptase, Integrase, Protease

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2
Q

What is the structure of HIV?

A

nucleic acid in center, surrounding core protein, matrix protein, envelop, envelop proteins

(retrovirus)

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3
Q

How many regulator genes are in HIV and which two are essential for replication?

A

6 total- tat and rev are essential

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4
Q

What are accessory genes?

A

Genes that are not essential for replication

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5
Q

Steps of replication process

A

attachmet of CD4 molecule, entry, uncoating

reverse transcriptase- RNA genome to proviral DNA

transported to nucleus

integrase unites proviral DNA to host DNA

host cell RNA polymerase transcribes proviral DNA to mRNA

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6
Q

Transmission of HIV

A

primarily through sexual contact

also through blood transfussion /perinatal infection

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7
Q

Pathogenesis of HIV

A

infection occurs in genital mucosa

HIV infects and kills lymphocytes leading to loss of CMI which predisposes to opportunistic infection

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8
Q

What happens to the helper T cells during HIV?

A

HIV kills helper T cells and cytoxic T cells also kill the virus infected helper T cells

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9
Q

What happens when helper T cells are reduced?

A

AIDS is produced

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10
Q

What is the main immune resistance to HIV?

A

cytotoxic T cells which controls the infection for a long time

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11
Q

What does polyclonal activation of B cells result in?

A

high immunoglobulin level which may cause auto immune disease through thrombocytopenia

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12
Q

3 stages of HIV infection

A
  1. acute stage
  2. Latent stage
  3. Late immuno deficiency stage
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13
Q

Describe acute stage of HIV

A

present 2-4 weeks: fever, lethargy, sore throat, generalized lymphadenopathy, rashes on trunk, arms and legs, leukopenia

resolves spontaneously in 2 weeks

Abs appear after 3 -4 weeks

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14
Q

Describe latent stage of HIV

A

set point occurs- new viral production- viral load will reamain constant for a number of years (asymptomatic period), fatigue and weight loss can occur- viruses present in lymph nodes

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15
Q

Describe Late immuno deficiency stage

A

Decline in number of CD4 cells- increase in severity and frequency of opportunistic infections- immuno compromised state

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16
Q

What is the screening test for HIV

A

ELISA- HIV abs present from the serum

envelop Abs rise gradually and stay high in the end

Confirmed by western blot test

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17
Q

Treatment of choice for HIV

A

ziduvidin and lamivudin and indinavir- all together called Highly active anti retroviral therapy

given for lifetime

NNRTI can also be given

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18
Q

Treatment for children with AIDS

A

2 nucleoside inhibitors and 1 non nucleoside inhibitor

treatment is life long

no vaccine available

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19
Q

Common opportunistic infections in AIDS patients

A

Pneumocystic caini, kaposis sarcoma

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20
Q

Viral opportunistic infection in AIDS patients

A

Herp simplex, vzv, CMV

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21
Q

Fungal opportunistic infections in AIDS patients

A

Candida (thrush), crypto, meningitis and histplasma capsulatum

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22
Q

Protozoal opportunistic infections in AIDS patients

A

toxoplasmosis

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23
Q

Bacterial opportunistic infections in AIDS patients

A

tuberculosis

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24
Q

What does integration of viral genome to host cell DNA result in?

Study These Flashcards
A

persistence infection

25
Where does Hepatitis A virus (HAV) replicate?
cytoplasm
26
Transmission of HAV?
fecal contamination of water
27
Who are the reservoirs of HAV?
children most affected, humans are the only reservoir
28
Pathogenesis of HAV
liver cells are infected causing cell necrosis- when infection clears, damage is repaired all viral infections look the same
29
Is HAV common in US?
YES- 50-75% of adults have abs
30
Clinical features of HAV?
after two weeks of infection, fever, anorexia, nausea, comiting and jaundice- dark colored urine, pale feces most cases resolve in 2-4 weeks most infections are asymptomatic
31
Vaccine for HAV?
YES- IgG provides life long immunity
32
Treatment for HAV?
no antiviral drug- only prevention
33
Prevention of HAV
proper sewage disposal, hand washing after defecation
34
Other name for Hep B virus?
Dane particle/hepadna virus
35
Describe look of HBV
enveloped DNA virus, partially double stranded
36
What does the envelop of HBV virus contain?
HBsAG- protein called surface antigen also known as Australian Ag
37
What is the capsid protein of HBV known as?
core Ag - HBcAg
38
Distribution of Hep B virus?
world wide distribution most prevelant in South east Asia- incidence of hepatocellular carcinoma here
39
Pathogenesis of Hep B
infects liver cells and causes necrosis cytoxic T cells kill viral infected liver
40
Is there a chronic carrier stage of Hep B?
YES- few DNA integrates to host cell DNA
41
What does Ag-Ab complexes in HBV patients lead to?
arthralgia, arthritis, urticaria immune complex glomerulonephritis
42
Percentage of HBV patients that become chronic carriers?
5%
43
What will occur in carrier HBV patients?
high incidence of hepatocellular carcinoma
44
What happens to patients who recover from HBV?
lifelong immunity HBsAb is responsible for this!
45
Clinical features of HBV patient
prevelant for 10-12 weeks- similar symptoms as in other hepatitis virus but more serious jaundice chronic infection leads to cirrhosis of liver/cancer
46
Treatment of chronic HBV infection
Alpha interferon and lamivudine (reverse transcriptase)
47
Prevention of HBV infection
vaccine available- vaccine contains HBsAg alone
48
What is available for passive immunity of HBV
Hyper immunoglobulin (anti serum) containing HBsAb
49
Who is the reservoir for Hep C (HCV)?
Human
50
Transmission of HCV?
blood transfussion, IV drug addicts
51
Where is HCV common?
US
52
Pathogenesis of HCV?
infects hepatocytes- strongly predisposes to hepatocellular carcinoma alcoholism enhances risk leading to cirrhosis
53
Clinical features of HCV
same as in HBV but milder jaundice features will also be there arthralgia, vasculitis and purpura occurs due to immune complexes
54
How do you detect HCV?
lab diagnosis by ELISA something that will show increase in liver enzymes elevated transaminase
55
Treatment of HCV?
alpha interferon and ribavirin pegylated interferon- long acting
56
Is there a vaccine for HCV?
NO- hyper immuno globulin
57
What is the arbo virus?
arthropod born viruses
58
What does Arbo virus cause?
eastern/western equine encephalitis west nile virus yellow fever

Microbiology (16 decks)

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