Lecture 17 Flashcards Preview

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Flashcards in Lecture 17 Deck (58):
1

What three virion enzymes does HIV carry?

Reverse transcriptase, Integrase, Protease

2

What is the structure of HIV?

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

(retrovirus)

3

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

6 total- tat and rev are essential

4

What are accessory genes?

Genes that are not essential for replication

5

Steps of replication process

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

6

Transmission of HIV

primarily through sexual contact

also through blood transfussion /perinatal infection

7

Pathogenesis of HIV

infection occurs in genital mucosa

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

8

What happens to the helper T cells during HIV?

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

9

What happens when helper T cells are reduced?

AIDS is produced

10

What is the main immune resistance to HIV?

cytotoxic T cells which controls the infection for a long time

11

What does polyclonal activation of B cells result in?

high immunoglobulin level which may cause auto immune disease through thrombocytopenia

12

3 stages of HIV infection

1. acute stage

2. Latent stage

3. Late immuno deficiency stage

13

Describe acute stage of HIV

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

14

Describe latent stage of HIV

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

15

Describe Late immuno deficiency stage

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

16

What is the screening test for HIV

ELISA- HIV abs present from the serum

envelop Abs rise gradually and stay high in the end

Confirmed by western blot test

17

Treatment of choice for HIV

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

given for lifetime 

NNRTI can also be given

18

Treatment for children with AIDS

2 nucleoside inhibitors and 1 non nucleoside inhibitor

treatment is life long

no vaccine available 

19

Common opportunistic infections in AIDS patients

Pneumocystic caini, kaposis sarcoma

20

Viral opportunistic infection in AIDS patients

Herp simplex, vzv, CMV

21

Fungal opportunistic infections in AIDS patients

Candida (thrush), crypto, meningitis and histplasma capsulatum 

22

Protozoal opportunistic infections in AIDS patients

toxoplasmosis

23

Bacterial opportunistic infections in AIDS patients

tuberculosis

24

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

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