Abstract
We report a case of HIV-1 superinfection in a patient with established HIV-2 infection. The patient was not taking antiretroviral therapy, in line with criteria in national guidelines, and reported no risk for infection with HIV-1. This case serves as a reminder that patients infected with HIV-2 remain susceptible to HIV-1 infection. The protective effect of antiretroviral treatment against HIV-1 infection should be a consideration in treatment decisions for individuals with HIV-2 infection.
Keywords
Introduction
Dual infection with HIV-1 and HIV-2 in the UK is rare, with only 35 cases reported to Public Health England (PHE) as of 2010. 1 HIV-2 is often viewed as less pathogenic than HIV-1 due to its slower progression; however, when a patient is significantly immunosuppressed, AIDS-related morbidity and mortality are clinically similar. 2
The protective effect of HIV-2 against HIV-1 infection was reported in one cohort in Senegal in 1995 3 but was not replicated in other studies.4,5 A more recent study on a cohort in Guinea-Bissau has suggested that HIV-2 may have an inhibitory effect on the rate of HIV-1 disease progression. 6 However, the long-term prognosis of dually infected patients remains poorly understood due to low numbers of patients and a lack of longitudinal data.
In this case report, we describe an antiretroviral therapy (ART)-naïve, HIV-2-infected patient who subsequently contracted HIV-1 whilst under our care. We suggest that the potential protective effect of ART in preventing acquisition of HIV-1 should be considered when deciding whether treatment should be initiated in patients with HIV-2 mono-infection.
Clinical section
A 60-year-old West African man was diagnosed with HIV-2 infection in October 2016, during an admission for an unrelated acute condition. His baseline HIV-2 viral load was 307 copies/ml and baseline CD4 cell count was 1787 cells/µl in the context of a total lymphocytosis. He tested negative for HTLV-1 and -2. Subsequent HIV-2 viral loads were <100 and undetectable, respectively. His case was discussed in a local multidisciplinary meeting (‘Virtual Clinic’), and UK guidelines 1 for the management of HIV-2 infection were reviewed. Indications for commencing ART were discussed in the context of his current clinical parameters. The option of clinical monitoring only was felt to be appropriate. This was discussed with the patient who was happy with this outcome.
At a scheduled visit in August 2018, a blood sample was sent for HIV-1 RNA quantification rather than the intended HIV-2 RNA check. HIV-1 RNA was detected at a level of 205,106 copies/ml on the Roche Cobas TaqMan assay (COBAS® TaqMan® HIV-1 Test, Roche, Basel, Switzerland). As a result of this finding, HIV serology was performed on a contemporaneous serum sample. HIV typing using the Biorad Geenius (Geenius
(a) Serum collected in August 2018, processed on the BioRad Geenius HIV 1/2 typing assay, showing positive reactions for the HIV-1 antigens p31, gp160, p24 and gp41 (test lines 3 to 6), in addition to the HIV-2 antigens gp36 and gp140 and control band. (b) Serum collected in October 2016, processed on the BioRad Geenius HIV 1/2 typing assay, showing positive reactions for the HIV-2 antigens gp36 and gp140 only in addition to the control band. Note: There was no suitable sample from January 2018 on which to perform serotyping.
On the basis of these results, it was concluded that this patient with longstanding HIV-2 infection had acquired HIV-1 infection between January and August 2018 (see Figure 2). Following confirmation of HIV-1 infection, the patient was commenced on antiretroviral therapy, active against both viruses, with Tenofovir disoproxil/Emtricitabine and Darunavir/Cobicistat, with good effect.
Timeline showing HIV-1 and HIV-2 diagnoses, respective viral loads and CD4 cell counts. Time of acquisition of HIV-1 is between January and August 2018.
Discussion
Although cases of HIV co-infection are common in West Africa, it is not often that one can demonstrate the temporality of superinfection as we have in this case. 7 We found two cases of superinfection described in the literature, however both were associated with significant declines in CD4 cell counts which alerted clinicians to the possibility of superinfection.8,9 Our patient has maintained a high CD4 cell count throughout and remained asymptomatic during acquisition of HIV-1 and at subsequent follow-up.
Whilst the patient did not meet the clinical or CD4 cell count criteria for initiation of ART based on current UK guidelines, 1 treating his HIV-2 with a tenofovir-based NRTI backbone may have had the benefit of providing protection against acquisition of HIV-1 infection, acting as pre-exposure prophylaxis (PrEP). 2 The role of commencing ART in this context was not considered to be necessary when risk factors were explored with this patient. In contrast with our national guidelines, the U.S. Department of Health and Human Services (DHHS) guidelines updated in July 2019, suggest that ART is started at or soon after diagnosis with HIV-2. 10
This case of HIV-1 superinfection in a patient with known HIV-2 infection provides a reminder that patients infected with HIV-2 remain susceptible to HIV-1 infection. The potential protective effect of treatment against HIV-1 infection should be considered when deciding whether treatment should be initiated in individuals with HIV-2 infection. The case also highlights the need for monitoring for HIV-1 infection in individuals with HIV-2 infection who may be at risk. These issues should be reflected in guidelines for the management of persons living with HIV-2 infection.
Footnotes
Acknowledgements
We would like express our thanks to the patient. (Note informed consent was obtained.)
Authors’ contribution
Each author has contributed to the written text of the case report.
Declaration of conflicting interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
