British HIV Association guidelines for the management of HIV‐2 2021

Abstract

Human immunodeficiency virus (HIV) is classified into two main types: HIV-1, which is closely related to a simian immunodeficiency virus (SIV) in chimpanzees, and HIV-2, which is closely related to an SIV in sooty mangabeys (SIVsmm) [1, 1, 3, 1. HIV-2 has a number of subtypes but only groups A and B have become epidemic [2, 2, 2. HIV-2 is a much less common HIV type than HIV-1; the exact prevalence is unknown, but an estimate has been made of 1–2 million people living with HIV-2 worldwide, including those with dual HIV-1 and HIV-2 infection [2, 2, 2. There are few current reliable prevalence estimates and the widely used rapid testing methods for HIV do not distinguish between HIV-1 and HIV-2 [3, 3. Although endemic in West Africa, the distribution of HIV-2 is limited and low prevalence in most settings, which means that understanding and experience of HIV-2, relative to HIV-1, among clinicians are often lacking. In addition, the majority of cohort and treatment studies quoted below, relate only to group A, adding to clinical uncertainty. Since HIV-2 was first recognised, evidence has accumulated regarding pathogenicity and prognosis. Although HIV-2 was initially considered non-pathogenic, it is now known that most untreated individuals with HIV-2 will experience disease progression, albeit at a slower rate compared to those with HIV-1 [4. Diagnosis, monitoring and management of HIV-2 remain challenging. Antiretroviral drugs are mostly developed for activity against HIV-1 group M, therefore many are inactive against HIV-2 and there are limited in vitro data for those drugs that may be used. To date, there have been no published randomised controlled trials of antiretroviral therapy (ART) for HIV-2 and our understanding is based on cohort studies and observational data. There are important differences in natural history between HIV-1 and HIV-2. HIV-2 carries a lower risk of horizontal and vertical transmission related to much lower plasma viral load, which is often undetectable without ART [1, 1, 3, 1. There is a slower but may at [4. disease of HIV-1 and HIV-2 is but at the rate in HIV-2 that a is disease is to in the majority of individuals with HIV-2 in the of ART [4. disease to HIV-2 is that to in and in HIV-2 the is lower and on treatment is less than in HIV-1 HIV-2 infection not against HIV-1 infection and dual infection may has that HIV-2 to of HIV-1 in dual infection clinical progression, compared to HIV-1 HIV-2 was initially in and the first published in been that individuals an closely related to simian than HIV-1; it was that the of HIV-2 is mangabeys are to the of West a prevalence of has been are for and are often in has been that into between and for HIV-2 group A and between and for group B has been less [1, 1, 3, 1. of HIV-2 have been groups A to HIV-2 groups A and B are HIV-2 groups have been in only two HIV-2 group A is common and has a group There do not to be clinical differences between groups A and but data are lacking. of the HIV-2 groups is to a viral groups are considered to be of to In to HIV-1, are only and have been HIV-2 is to West prevalence has been in and which prevalence in the the prevalence at in and to in individuals in HIV-2 is in and and has to and A in the number of HIV-2 in in the is to the of and is to the and of HIV-2 to and [1, 1, 3, 1. HIV-2 is in of those with to and prevalence in is to be a prevalence of dual HIV-1 and HIV-2 in and have the number of people living with HIV-2 in with and people HIV-2 has been in a number of including the and the and have a rapid in the prevalence of HIV-2 in that the infection may become the of the prevalence of HIV-2 may be to lower transmission in risk risk of with HIV-1 in studies is the that HIV-2 prevalence has among than to a risk of infection than of the including of are in the HIV which was in and the and an the current and the for between and the HIV-2 studies on and on HIV and HIV for the evidence was and group with in the the of and group for and the of evidence for studies and and the of are based on the clinical and experience of the an of important clinical for which there is is there to but the of is clinical that are to it and the is the the published for and A of is in with only in with data. of HIV-2 infection and Although there may be many in the HIV-1 and HIV-2 are and there are differences that to be In the HIV-1 is the common and of the is for people living with a the differences between HIV-1 and HIV-2 may be and be made to people living with HIV-2 and important of treatment and people living with HIV-2 in the have West have to with West means that there may be in group than for those with of HIV-1 has a and evidence with treatment and is not the for HIV-2, there are only limited data on the of monitoring and it is to on the of evidence the it be that will it be that for those on undetectable will for people with HIV-2, there is no it is to the for those have an undetectable viral in the of much of the and in for HIV-1 be to for HIV-2 There are differences between HIV-1 and HIV-2 that are in to be and to in the of people in and for and of HIV-2 are compared with HIV HIV-1 and HIV-2. to people may that have been with HIV-1 not that there are of and it may be of HIV-2 is and viral and testing are at and it to HIV-2 groups are that it is common for and viral to to which in treatment of HIV-2 is slower compared to people living with untreated HIV-2 have undetectable viral for many and may not experience a in to ART for HIV-2 less than for of treatment with monitoring may be an of for HIV-2, there are many ART is in that ART be a of HIV-2 is viral may that the risk of transmission of HIV-2 to is lower than for may have been living with HIV-2 for than is for HIV-1, but may the of and the of to it be that HIV-2 is to than antiretroviral developed for HIV-1 and HIV-2 has to of There is the to and of treatment for HIV-2. limited of means that there are and a for people living with HIV-2, and may be Although and the low of people living with HIV-2 in the may that have limited experience of HIV-2, treatment and the experience of people with HIV-2. is to HIV-1 on to the of to antiretroviral drugs to with may not be to HIV-2. for HIV-2 may to be closely than for HIV-1, to the risk of There is evidence to that may low undetectable viral in people with HIV-2 may that is in people with HIV-2, compared with be the most of and to differences between HIV-2 and HIV-1, and the that for people with HIV-2 is people are and there are may be and Although is often at may to be considered with in the of HIV-2, most of the experience in the is of to and drugs to may than be the for the risk of on may be with and There are of to antiretroviral drugs is less of an than for may for There is to for clinical in HIV-2. a clinical the for HIV-1 with to monitoring and in our understanding of HIV-2 and relative that a is be in with and people for people with HIV-2 may have understanding of the differences compared with HIV-2 is the of infection the of testing for HIV-2 infection on a made at for and testing be with a for HIV testing the In the the to the of HIV-2 infection is and the HIV-1 and HIV-2 in the for to testing for HIV-2 the for HIV-1 A for HIV-1 and HIV-2 is are to a two including that between HIV-1 and HIV-2. HIV-2 in is to the of HIV-2 in the with HIV-1, the for HIV-2 is not a the has is to for which in a has been to the is considered of the two with for HIV type is considered for of and HIV-2 A may be in the of HIV-2 of HIV-2 infection only be made on the of HIV-2 to for a HIV-2 infection is but the of a transmission clinical may of the have become the of HIV but has in the of HIV-1 of in is to be for HIV-1 in of HIV-2 the is an and be to A in a therefore be with of the in which a HIV-2 infection may not be for HIV-2 is considered to be at for HIV a at a at which it has a of infection the of a HIV is and and to HIV-2 the be HIV-1 be used to HIV-2 and has the for which may be in infection of the between HIV-1 and HIV-2, in may to there may have been in viral not be considered to that the has dual HIV-1 and HIV-2 is important to that a may have an of HIV the and of for HIV-2 not at A of an HIV-2 to the of the to HIV-1 and HIV-2 HIV-2 are not in the the of HIV-2 infection on on the be an HIV-2 viral but a of with HIV-2 do not have a HIV-2 viral load, a be not the has a low of and may be in dual infection is not the to HIV-2 infection in the of is for the of HIV-2 is in of which be to the a it to be the is of and HIV-2 that has been into of in HIV-2 with In studies in West Africa, the of individuals with viral between and viral will to and clinical between of monitoring of to treatment of disease in those do not the plasma viral of HIV-2 be with clinical for A of HIV-2 do not initially have a may without a plasma viral for management of are in to of HIV-2 B viral is than of A, to a the viral including the may in and the between viral and clinical in B methods to HIV-2 viral are based on have the to with natural in and of and In addition, HIV-2 are HIV viral which a is the which the activity of plasma Although the is less than the and distinguish between HIV-1 and HIV-2 in it has in limited with of HIV-2 viral testing is limited in the at the of there are only two for methods developed that have been published in and the are of the has to the in of and and for of HIV-2 viral data with to clinical HIV-2 testing is the only for there are no that be used to clinical in the an HIV-2 is and of HIV-2 viral for which be is to HIV-2 the viral be at of the two the HIV-2 viral is but the of it may be to testing with the of HIV drugs for which testing may be are the and HIV-2 is to and the to for HIV-2 testing is to that used for of viral of to of of for the is for of and for the of that are to of used in the are and and are based on clinical the of HIV-2 is which has a of for in viral of in a viral at a less than are to be will have clinical for of HIV-2 infection is for is considered in in the There are no published randomised controlled trials to the of ART in HIV-2, the of the group to based on evidence is cohort which are to and are limited the ART at the the was In addition, the majority of the cohort studies West of to be considered There is no and regarding the for treatment for people with HIV-2. of and Human ART at HIV-2 to disease and transmission of HIV-2 to based on HIV-1 the and HIV-2 in to ART in with HIV the a that treatment are based on a of and clinical many of is the clinical of HIV-2 compared with is a lower plasma viral load, and slower clinical progression, the of is and the for people with HIV-1 In most settings, the of individuals with an undetectable viral is between and the evidence viral with treatment is is to the of individuals with viral for and the limited of monitoring in many of the West cohort of a cohort in a between and viral load, with risk to that of people without HIV for the of people living with HIV-2 undetectable viral at a of and with the of including a of is of the and including of viral data in the is to and the on among those not on There is a of evidence with treatment with of the cohort studies in and West have a in on treatment an ART was used A the including individuals with HIV-1 and HIV-2 in West a in at among people with a was among individuals with a lower cohort including of in and a in in individuals a at of of with a the of treatment in of treatment with an undetectable plasma in the of to HIV treatment compared with for those may be slower among people with HIV-2 than among those with HIV-1, a observational cohort in West the in between people with HIV-1 and HIV-2 with no in was not in observational data the HIV-1 and HIV-2 the treatment to was in people with HIV-2 and in those with HIV-1, with an between groups of for viral and ART Although in the in on treatment is not and two of data only a in with individuals no ART In an observational in HIV-1 and HIV-2 in there was no in on treatment with a was not in people with HIV-1 in the evidence that without HIV-2 infection will to and in the majority of with among people with HIV-2 than among those without HIV [4. a cohort of in a to disease and a among individuals with HIV-2 than among those with HIV-1 [4. that people with HIV-2 to clinical at compared with people with HIV-1 may be the of with but ART [4. that is and that disease is to but slower than in those with HIV-1, clinical there was a for the to ART for HIV-1 the in ART has been to be in transmission in and have with is and that the to HIV-2 and of the for that those with HIV-2 In to ART for individuals with HIV-2 is to be against HIV-1 of of HIV-1 be ART is not and HIV-1 infection has been in an with HIV-2 of treatment will the in a majority of with ART and on an is to which individuals with undetectable viral and will treatment and studies to people without HIV among individuals with HIV-2 have undetectable viral and ART ART is to be in people with an undetectable HIV-2 viral and compared to those with HIV-1 and the of disease is in people with HIV-2 have undetectable viral and is than in HIV-1 with lower In addition, treatment are and and there may be of group in including in There are clinical in which a to treatment of evidence of are in in the and and that individuals with HIV-1 of clinical and is based on evidence two randomised controlled trials to the of ART and the to transmission of HIV-1 people on ART but with clinical of ART trials for and two in individuals with HIV-1 and of to ART compared with on and the evidence for treatment now ART in of ART for people with HIV-2 is limited evidence people with HIV-1 and HIV-2 with an of the group of West in in people with HIV-1, HIV-2 and dual infection of an ART In a observational including people with dual infection living in of those on treatment of a on ART is to that individuals with dual infection are with a to of and monitoring for viral and testing for [2, 2, 2. limited data that may be to in HIV-2 than HIV-1 and that in HIV-2 is a to limited treatment it is of a against in a in which there is the of dual infection HIV-2 an for an HIV-2 viral a is based on evidence for the management of infection with HIV-1 infection is infection a of the of HIV few of individuals with and of infection with HIV-2 clinical with those in HIV-1 with treatment a regarding the and of treatment is the and of current treatment it is that the of will the in the majority of of and in be is based on evidence in HIV-1 and A not evidence people with HIV-2 and in West Africa, the prevalence of with not to HIV type individuals with for treatment are based on evidence of and of to people with HIV-2 and and be on ART for those for treatment of evidence with HIV-1 and that is with of and an risk of disease and at to be with A in that than are important to in individuals risk of in people with and HIV-1 to be but not of ART for is a prevalence of in people on compared to those with and have not been B treatment to be in and is to in people with a low for is rapid ART is in individuals of have that is in to of people with HIV-1 and on the of treatment in individuals with HIV and is in the for the management of HIV-1 infection ART for people with HIV-2 and a viral for 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