Coinfection with HIV and human T lymphotropic virus type 1: what is the real impact on HIV disease?

Early and Successful Combination Antiretroviral Therapy Normalizes Survival Time in Patients Coinfected With Human Immunodeficiency Virus and Human T-cell Lymphotrophic Virus Type 1

BACKGROUND

Coinfection with human T-cell lymphotrophic virus type 1 (HTLV-1) is associated with shorter survival for adults and children infected with human immunodeficiency virus (HIV), although the reasons remain a matter of debate. We evaluated the factors associated with survival time in a large cohort of HIV/HTLV-1-coinfected and HIV-monoinfected individuals on combination antiretroviral therapy (cART).

METHODS

In a nested, retrospective case-control study (1:1), we reviewed medical records of people with HIV infection on cART in a referral AIDS center in Salvador, Brazil. We matched 149 patients coinfected with HTLV-1 (cases) by age at HIV diagnosis and sex, to an equal number of HTLV-uninfected persons (controls). Death rates, survival time, baseline and current CD4 cell count, last HIV-1 RNA plasma viral load (pVL), and causes of death were compared between groups.

RESULTS

The overall mortality rate was 2.1 person-years (76 deaths, 53 among coinfected patients). Survival time for cases (16.7 ± 0.7 years) was significantly shorter than for controls (18.1 ± 0.4 years; P = .001). Among patients with pVL >50 copies/mL, coinfected patients had a shorter survival time (8.4 ± 0.8 years) than monoinfected ones (12.9 ± 1.4 years; P = .02), regardless of pVL magnitude. However, survival time did not differ for HIV-monoinfected (19.0 ± 0.4 years) or coinfected patients (20.2 ± 0.6 years) presenting with pVL <50 copies/mL (P = .5). Deceased coinfected patients had higher initial CD4 count (417 ± 219 cells) than monoinfected ones with the same outcome (177 ± 160 cells; P = .004), while survivors had similar CD4 cell count at baseline, regardless of HTLV status.

CONCLUSIONS

Successful cART is able to normalize survival for coinfected patients and should be introduced for all coinfected patients, regardless of CD4 cell count.HIV/human T-cell lymphotrophic virus type 1 coinfection is believed to decrease survival of coinfected patients. In this case-control study, we demonstrate that successful combination antiretroviral therapy (last HIV viral load <50 copies/mL) is able to improve survival of coinfected patients to levels observed for those monoinfected.

First description of HTLV-1/2 seroprevalence in HIV-infected inmates in Mozambique

No study has yet been conducted to estimate the burden of co-infection of HIV and HTLV-1/2 in inmates in sub-Saharan Africa. To investigate prevalence of co-infection in inmates in Mozambique, a total of 2140 inmates were screened for HIV, of which 515 were HIV seropositive. All HIV seropositive inmates were further screened for HTLV infection, and eight (1.55%) were co-infected. Co-infection was higher in females (3.45% [2/58; CI: 0.42-11.91]) as compared to males (1.35% [6/445; CI: 0.55-3.06]). Early screening of HTLV in prisons is urgently needed in Mozambique in order to improve the care provided to incarcerated individuals, including initiation of ART.

HTLV-1 and HIV-1 co-infection: A case report and review of the literature

HTLV type 1 and 2 are both involved in actively spreading epidemics, affecting over 15 million people worldwide. HTLV-1 has been described as the more clinically significant one, being associated with diseases such as adult T-cell leukemia and tropical spastic paraparesis. We report here a case of tropical spastic paraparesis in an HIV-positive patient who did not report any history of travel or residence in an HTLV endemic area.

A 57 year old African-American male was admitted to the hospital due to bilateral upper and lower extremity weakness associated with stiffness. He had recently been diagnosed with HIV. His physical examination showed mild to moderate decreased motor strength, in both upper extremities and marked loss in both lower extremities. This was associated with hyperreflexia and clonus. Sensory function was intact. He looked cachectic and had several psoriatic plaques on both lower and upper extremities. Laboratory work-up showed a CD4 count decreased to 94 cells/mm³ and a HIV viral load of 273,000 copies/mL. Based on serum positivity for HTLV type 1 and the patient's clinical presentation suggestive of upper and lower motor neuron dysfunction, the diagnosis of tropical spastic paraparesis was made.

HTLV and HIV share the same routes of transmission and the same tropism for T-lymphocytes. Co-infection occurs probably more frequently than we are aware, since testing for HTLV is not routinely performed in outpatient HIV clinics.

HTLV-1/-2 and HIV-1 co-infections: retroviral interference on host immune status

The human retroviruses HIV-1 and HTLV-1/HTLV-2 share similar routes of transmission but cause significantly different diseases. In this review we have outlined the immune mediated mechanisms by which HTLVs affect HIV-1 disease in co-infected hosts. During co-infection with HIV-1, HTLV-2 modulates the cellular microenvironment favoring its own viability and inhibiting HIV-1 progression. This is achieved when the HTLV-2 proviral load is higher than that of HIV-1, and thanks to the ability of HTLV-2 to: (i) up-regulate viral suppressive CCL3L1 chemokine expression; (ii) overcome HIV-1 capacity to activate the JAK/STAT pathway; (iii) reduce the activation of T and NK cells; (iv) modulate the host miRNA profiles. These alterations of immune functions have been mainly attributed to the effects of the HTLV-2 regulatory protein Tax and suggest that HTLV-2 exerts a protective role against HIV-1 infection. Contrary to HIV-1/HTLV-2, the effect of HIV-1/HTLV-1 co-infection on immunological and pathological conditions is still controversial. There is evidence that indicates a worsening of HIV-1 infection, while other evidence does not show clinically relevant effects in HIV-positive people. Possible differences on innate immune mechanisms and a particularly impact on NK cells are becoming evident. The differences between the two HIV-1/HTLV-1 and HIV-1/HTLV-2 co-infections are highlighted and further discussed.

Coinfection by HIV-1 and human lymphotropic virus type 1 in Brazilian children is strongly associated with a shorter survival time

Coinfection by HIV-1 and human lymphotropic virus type 1 is a frequent finding in South America, the Caribbean and Africa, and its prevalence varies from 4% to 16% according to the available reports. Although the impact of coinfection on HIV disease is still controversial, there is evidence supporting the contention that it can affect the natural history of both infections. No information is available on coinfection in children. In a nested case-control study, we evaluated 35 coinfected children matched by age, gender, and time of diagnosis to HIV monoinfected control subjects. At the first evaluation, coinfected children were more likely to present any signs and symptoms of disease (P < 0.001) than monoinfected ones despite having significantly higher CD4 cells count (1429 ± 608 vs 928 ± 768 cells/mm; P = 0.003). The proportion of deaths was higher (80%) for coinfected children than for HIV-1-infected ones (20%; relative risk, 2.1; 95% confidence interval, 1.4-3.1; P = 0.01). Survival was also significantly shorter for coinfected children (P = 0.001). Coinfection by HIV-1 and human lymphotropic vírus type 1 in Brazilian children was strongly associated with higher mortality and shorter survival time despite coinfected patients having a higher baseline CD4 cells count.

Co-infection by human immunodeficiency virus type 1 (HIV-1) and human T cell leukemia virus type 1 (HTLV-1): does immune activation lead to a faster progression to AIDS?

BACKGROUND

Recent data have shown that HTLV-1 is prevalent among HIV positive patients in Mozambique, although the impact of HTLV-1 infection on HIV disease progression remains controversial. Our aim was to determine the phenotypic profile of T lymphocytes subsets among Mozambican patients co-infected by HIV and HTLV-1.

METHODS

We enrolled 29 patients co-infected by HTLV-1 and HIV (co-infected), 59 patients mono-infected by HIV (HIV) and 16 healthy controls (HC), respectively.For phenotypic analysis, cells were stained with the following fluorochrome-labeled anti-human monoclonal antibodies CD4-APC, CD8-PerCP, CD25-PE, CD62L-FITC, CD45RA-FITC. CD45RO-PE, CD38-PE; being analysed by four-colour flow cytometry.

RESULTS

We initially found that CD4+ T cell counts were significantly higher in co-infected, as compared to HIV groups. Moreover, CD4+ T Lymphocytes from co-infected patients presented significantly higher levels of CD45RO and CD25, but lower levels of CD45RA and CD62L, strongly indicating that CD4+ T cells are more activated under HTLV-1 plus HIV co-infection.

CONCLUSION

Our data indicate that HTLV-1/HIV co-infected patients progress with higher CD4+ T cell counts and higher levels of activation markers. In this context, it is conceivable that in co-infected individuals, these higher levels of activation may account for a faster progression to AIDS.

HTLV-I infection is not associated with a higher risk of death in Peruvian HIV-infected patients

Limited and contradictory information exists regarding the prognosis of HIV/HTLV-I co-infection. Our goal was to estimate the effect of HTLV-I infection on mortality in HIV-infected patients at a HIV reference center in Peru. We studied a retrospective cohort of HIV-infected patients, who were exposed or unexposed to HTLV-I. Exposed patients were Western Blot (WB) positive for both retroviruses. Unexposed patients were WB positive for HIV, and had least one negative EIA for HTLV-I. These were selected among patients who entered our Program immediately before and after each exposed patient, between January 1990 and June 2004. Survival time was considered between the diagnosis of exposure to HTLV-I and death or censoring. Confounding variables were age, gender, baseline HIV clinical stage, baseline CD4+ T cell count, and antiretroviral therapy. We studied 50 exposed, and 100 unexposed patients. Exposed patients had a shorter survival compared to unexposed patients [median survival: 47 months (95% CI: 17-77) vs. 85 months (95% CI: 70-100), unadjusted p = 0.06]. Exposed patients had a higher rate of mortality compared to unexposed patients (HIV/HTLV-I (24/50 [48%]) vs. HIV only (37/100 [37%]), univariable p = 0.2]. HTLV-I exposure was not associated to a higher risk of death in the adjusted analysis: HR: 1.2 (0.4-3.5). AIDS clinical stage and lack of antiretroviral therapy were associated to a higher risk of dying. In conclusions, HTLV-I infection was not associated with a higher risk of death in Peruvian HIV-infected patients. Advanced HIV infection and lack of antiretroviral therapy may explain the excess of mortality in this population.

Coinfecting viruses as determinants of HIV disease

The human body constitutes a balanced ecosystem of its own cells together with various microbes ("host-microbe ecosystem"). The transmission of HIV-1 and the progression of HIV disease in such an ecosystem are accompanied by de novo infection by other microbes or by activation of microbes that were present in the host in homeostatic equilibrium before HIV-1 infection. In recent years, data have accumulated on the interactions of these coinfecting microbes-viruses in particular-with HIV. Coinfecting viruses generate negative and positive signals that suppress or upregulate HIV-1. We suggest that the signals generated by these viruses may largely affect HIV transmission, pathogenesis, and evolution. The study of the mechanisms of HIV interaction with coinfecting viruses may indicate strategies to suppress positive signals, enhance negative signals, and lead to the development of new and original anti-HIV therapies.

Patterns of In vitro Lymphoproliferative Responses Among HTLV-1-infected Subjects: Upregulation by HTLV-1 During HIV-1 Co-infection

The present study evaluated the in vitro response to different mitogens and a candidin antigen (CMA) in Human T-cell lymphotropic virus type 1 (HTLV-1) and co-infected HIV-1/HTLV-1 patients, to identify if this co-infection may modify the spontaneous lymph proliferative response. Peripheral blood mononuclear cells from 72 healthy seronegative controls, 75 asymptomatic HTLV-1-infected carriers, 42 HAM/TSP cases, 33 solely HIV-1-infected subjects and 24 HIV-1/HTLV-1 patients were assayed in the presence and absence of mitogens (PHA, PWM and OKT3) and CMA. The HAM/TSP group had the highest proliferation rate at 3 and 6 days after culture. HAM/TSP cases showed decreased response to PHA, compared with asymptomatic HTLV-1 subjects, and most important, the co-infected HIV-1/HTLV-1 cases presented a similar response to HTLV-1-infected subjects after 3 days of culture. The singles HIV-1-infected group had decreased in vitro response. It appears that during co-infection, the HTLV-1 regulatory proteins overwhelm the action of HIV-1 regulatory proteins.