HIV-2 Flashcards
Which HIV type is most common HIV-1 or HIV-2?
HIV-1
What is the relationship between HIV-2 and simian immunodeficiency virus (SIV)?
Closely related to SIV in sooty mangabeys
What is the difference in the relationship between HIV-1, HIV-2 and SIV?
HIV-1 related to SIV in chimpanzees
HIV-2 related to SIV in sooty mangabeys
What is the prevalence worldwide of HIV-2?
1-2 million
Where is HIV-2 endemic?
West Africa
How many subtypes of HIV-2?
NINE (9)
Only A & B epidemic
Describe the limitations of evidence in HIV-2 prevalence and natural course.
Cohort and treatment studies - group A only
Small worldwide number
Rapid HIV test often does not differentiate
What is the the pathogenicity of HIV-2?
Most untreated individuals will have disease progression
Slower progression than HIV-1
Describe limitations of evidence for treatment of HIV-2
ART developed for HIV-1 group M
Limited in vitro evidence
Evidence based on cohort and observational studies only
What is the difference between HIV-1 and HIV-2 and transmission?
HIV-2 lower risk of horizontal and vertical transmission
Why is transmission less likely with HIV-2 vs HIV-1?
Lower plasma viral load, often undetectable
What is the relationship between CD4 and AIDS in HIV-2?
AIDS defining illness can occur at higher CD4 count
What is the progression of CD4 in HIV-2 vs HIV-1?
CD4 count in HIV-2 slower decline
What is the disease trajectory in HIV-2 vs HIV-1?
HIV-2 progresses at half the rate of HIV-1
Is there any difference in clinical disease/AIDS-defining illness due to HIV-2 vs HIV-1?
No
Which TWO class of ART can resistance more easily develop?
NRTI
PI
Does HIV-2 protect against HIV-1?
No but may delay clinical progression of HIV-1
What type of animal SIV is the HIV-2 origin?
SIV smm
What human contact is there with sooty mangabeys in West Africa?
Hunted for FOOD
Kept as PETS
When did SIVsmm likely jump from sooty mangabey to human?
1905-1945
What was the prevalence of HIV-2 in West Africa in 1980s?
> 1% in some parts
Where in West Africa reported the highest prevalence of HIV-2?
Guinea-Bissau
What is the prevalence of HIV-2 in GUinea Bissau?
8%
What is the prevalence of HIV-2 in over 40 year olds in GUinea Bissau?
20%
Dissemination of HIV-2 outwith West Africa is attributed to which event and which country?
War of Independence (1963-1974)
Portugal
Which countries in Europe have the highest prevalence of HIV-2?
FRANCE
PORTUGAL
What is the number of people living with HIV 2 in FRANCE?
1000
What is the number of people living with HIV 2 in PORTUGAL?
2000
What are the possible reasons for decreasing prevalence of HIV-2?
lower transmission rate
change in risk behaviour
reduced healthcare associated infection
competition with HIV-1
When should ART be started in HIV-2?
At new diagnosis
evidence to support limited
Why is adherence so important in ART for HIV-2?
INTRINSIC resistance therefore less options
LOWER THRESHOLD for resistance
LIMITED SWITCH options
Why is regular CD4 monitoring encouraged for HIV-2?
VL is often undetectable and therefore does not help with monitoring of therapy efficacy and health status
What is general pathway of testing and confirming HIV-2 infection?
4th generation Ag/Ab SCREENING
at least 2 CONFIRMATORY tests
1 test that can DIFFERENTIATE between HIV1 and HIV2
What is the limitation of the 4th generation Ag/Ab test for HIV in context of HIV-2?
p24 antigen detective designed towards HIV-1
therefore this test is only ANTIBODY test for HIV-2 and has no utility in early infection
Is there an avidity test of HIV-2?
No
What is the limitation of the HIV-2 RNA viral load test?
often undetectable therefore no use if trying to confirm HIV-2 infection
What additional test can be used to confirm HIV-2, if screen is indeterminate and viral load undetectable?
measure HIV-2 PROVIRAL DNA
What is the proportion of PLW HIV-2 who have undetectable viral load and are ART naive?
25-40%
Can PLW HIV-2 progress even if viral load undetectable?
Yes
What is the relationship between HIV-2 detectable viral load and clinical progression?
Higher risk or rate of progression c/w undetectable
Which HIV-2 subtype is harder to measure viral load for?
B
What is the discordance observed between viral load and clinical progression in subtype B HIV-2?
Clinical progression more regularly observed with undetectable VL c/w subtype A
Why might clinical progression be more likely in subtype B HIV-2 and undetectable VL?
Harder to test for VL for subtype B therefore may be incorrectly measured as undetectable
What type of resistance testing if available for HIV-2?
Genotypic