HTLV-II among Italian intravenous drug users and hemophiliacs

Clinical and Public Health Implications of Human T-Lymphotropic Virus Type 1 Infection

Human T-lymphotropic virus type 1 (HTLV-1) is estimated to affect 5 to 10 million people globally and can cause severe and potentially fatal disease, including adult T-cell leukemia/lymphoma (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The burden of HTLV-1 infection appears to be geographically concentrated, with high prevalence in discrete regions and populations. While most high-income countries have introduced HTLV-1 screening of blood donations, few other public health measures have been implemented to prevent infection or its consequences. Recent advocacy from concerned researchers, clinicians, and community members has emphasized the potential for improved prevention and management of HTLV-1 infection. Despite all that has been learned in the 4 decades following the discovery of HTLV-1, gaps in knowledge across clinical and public health aspects persist, impeding optimal control and prevention, as well as the development of policies and guidelines. Awareness of HTLV-1 among health care providers, communities, and affected individuals remains limited, even in countries of endemicity. This review provides a comprehensive overview on HTLV-1 epidemiology and on clinical and public health and highlights key areas for further research and collaboration to advance the health of people with and at risk of HTLV-1 infection.

Neurological Aspects of HIV-1/HTLV-1 and HIV-1/HTLV-2 Coinfection

Simultaneous infection by human immunodeficiency viruses (HIV) and human T-lymphotropic viruses (HTLV) are not uncommon since they have similar means of transmission and are simultaneously endemic in many populations. Besides causing severe immune dysfunction, these viruses are neuropathogenic and can cause neurological diseases through direct and indirect mechanisms. Many pieces of evidence at present show that coinfection may alter the natural history of general and, more specifically, neurological disorders through different mechanisms. In this review, we summarize the current evidence on the influence of coinfection on the progression and outcome of neurological complications of HTLV-1/2 and HIV-1.

Coinfection with HIV-1 and human T-Cell lymphotropic virus type II in intravenous drug users is associated with delayed progression to AIDS

Human T-cell lymphotropic virus (HTLV) type II has spread among intravenous drug users (IDUs), many of whom are coinfected with HIV-1. We have investigated the rate of HTLV-II infection in 3574 Italian IDUs screened for HIV-1, HTLV-I, and HTLV-II from 1986 to the present. HTLV-II proviral load was determined by a real-time polymerase chain reaction specifically designed for tax amplification. The frequency of HTLV-II infection was 6.7% among HIV-1-positive subjects and 1.1% among HIV-1-negative subjects (P < 0.0001). For examination of AIDS progression, a group of 437 HIV-1-monoinfected subjects and another group of 96 HIV-1/HTLV-II-coinfected subjects were monitored. Enrollees were matched at entry by CD4 cell counts and followed for an average of 13 years. HIV-1/HTLV-II coinfection was associated with older age (P < 0.0001) and higher CD4 (P < 0.0001) and CD8 (P < 0.001) cell counts compared with monoinfected IDUs. The number of long-term nonprogressors for AIDS was significantly higher (P < 0.0001) among coinfected patients (13 [13.5%] of 96 patients) than HIV monoinfected patients (5 [1.1%] of 437 patients), showing that HTLV-II exerts a protective role. An increased incidence of liver disease and hepatitis C virus positivity among coinfected IDUs was observed. Five coinfected subjects undergoing antiretroviral therapy showed a significant (P < 0.05) increase in HTLV-II proviral load concomitant to a decrease in HIV-1 viremia, suggesting that the treatment is ineffective against HTLV-II infection.

Increased risk of developing peripheral neuropathy in patients coinfected with HIV-1 and HTLV-2

One thousand one hundred fifty-two HIV-1-positive patients were screened for HTLV-2 infection, and the AIDS-free coinfected individuals were consecutively included in a longitudinal study with the aim of investigating the role of HTLV-2 in the progression to AIDS and the development of specific neurologic diseases. Two matched HIV-1-positive/HTLV-2-negative controls for each coinfected individual were also enrolled in the study. HTLV-2 infection was found in 95 (8.2%) of the HIV-1-positive patients, 30 of whom were followed up for a median of 28.5 months. No significant differences were observed between them and the patients infected with HIV-1 alone in terms of the rate of decline in CD4 cell counts, progression to AIDS, or AIDS mortality, but they had an increased risk of developing peripheral neuropathy (hazard ratio, 3.3; 95% confidence interval, 1.3-8.0; p =.009). One coinfected patient developed myelopathy during the follow-up. In the second part of the study, aimed at preliminarily assessing the effect of highly active antiretroviral therapy (HAART) on the incidence of peripheral neuropathy, we extended our observations to two groups of coinfected and singly infected individuals receiving HAART. An 80% decrease in incidence of peripheral neuropathy was observed among both groups without any significant difference between them. These results support the hypothesis that HTLV-2 plays a role in the development of neurologic abnormalities in HIV-1-infected patients and suggest that the immune reconstitution due to HAART may limit the activity of HTLV-2 as an opportunistic agent.

High prevalence of false-negative anti-HTLV type I/II enzyme-linked immunosorbent assay results in HIV type 1-positive patients

A high frequency of false-negative anti-HTLV-I/II ELISA results has been reported by several authors. To verify the possible underestimate of the prevalence of HTLV-II infection in subjects infected by HIV-1, we used the PCR to investigate the presence of HTLV DNA in peripheral blood mononuclear cells (PBMCs) collected from a group of 67 HIV-1-positive anti-HTLV-I/II ELISA-negative individuals; the study population included 31 patients with HIV-1-related peripheral neuropathy (PN), 15 with non-Hodgkin lymphoma (NHL), and 23 without PN or NHL. Two subjects had both PN and NHL. All of the patients who were positive at PCR were investigated for the presence of serum anti-HTLV-I/II antibodies by means of Western blot (WB). Eighteen (26.9%) of the 67 anti-HTLV-I/II ELISA-negative patients had HTLV DNA in their PBMCs and WB-detectable serum antibodies directed against one or more HTLV antigens. The individuals affected by predominantly sensory polyneuropathy (PSP) had a significantly higher prevalence of HTLV DNA than the others. All of the patients in whom HTLV-I/HTLV-II discrimination was successful had HTLV-II, with the exception of one patient who was infected by HTLV-I. The present study confirms the possibility of HTLV infection in the absence of ELISA-detectable serum anti-HTLV-I/II antibodies, especially in the particular setting of HIV-1-infected individuals. Moreover, the fact that the prevalence of HTLV DNA was significantly higher in the subjects affected by predominantly sensory polyneuropathy further supports the possibility of an association between HIV-1-related PSP and HTLV-II.

Prevalence and risk factors for HTLV-II infection in 913 injecting drug users in Stockholm, 1994

The prevalence and risk factors for acquisition of human T-cell lymphotropic virus type I and II (HTLV-I and II) were investigated in a prospective study of 913 injecting drug users (IDUs) in Stockholm in 1994. Epidemiologic data were recorded, and blood samples were tested for antibodies against HTLV-I and HTLV-II; human immunodeficiency virus (HIV) types 1 and 2; and hepatitis A (HAV), B (HBV), C (HCV), and D (HDV). Positive serologic results for HTLV were confirmed by Western blot (WB) and polymerase chain reaction (PCR). Of the 905 participants with conclusive HTLV-II status, 29 (3.2%) were HTLV-II positive, and all but three were of Nordic descent. None was HTLV-I infected. One person was infected as early as 1981, before HIV had reached the IDU population in Sweden. The prevalence of HTLV-II infection was 12% among HIV-1-seropositive and 1.8% among HIV-1-seronegative participants. The overall seroprevalences were 14% for HIV-1, 0% for HIV-2, 41% for HAV, 75% for HBV, 92% for HCV, and 8% for HDV. Although amphetamine has been the main injecting drug in Sweden for several decades, heroin abuse combined with a debut of injecting drugs before 1975 was identified as the most important risk factor associated with HTLV-II infection. HAV and HIV seropositivity were also independent risk factors.

Prevalence of HTLV-I and HTLV-II infections among HIV-1-infected asymptomatic individuals in São Paulo, Brazil

Human immunodeficiency virus (HIV-1)-infected subjects with acquired immunodeficiency syndrome (AIDS) are often infected with multiple pathogens. In particular, HTLV-I and HTLV-II infections have been found more frequently in AIDS patients than in asymptomatic individuals in Europe and Japan. We carried out a serosurvey among asymptomatic HIV-1-infected subjects in São Paulo, Brazil and compared our results with those of other investigators. In this study, we found HTLV infection in 1.5% of 266 asymptomatic and 14% of 28 AIDS patients. Epidemiological data obtained from patients pointed out the use of intravenous drugs as the principal risk factor for acquiring retroviruses. In conclusion, our results are in accordance with other studies done in Brazil and elsewhere where the principal risk group for HIV/HTLV-I/II coinfection was IDU.

Human T-cell leukemia virus type II infection among high risk groups and its influence on HIV-1 disease progression

The prevalence and the risk factors of the human T-cell leukemia virus type I/II (HTLV-I/II) infection were evaluated among 552 individuals at high risk for HIV-1. HTLV infections showed a low (1.6%) prevalence, were restricted to intravenous drug addicts and were due to HTLV-II alone. Moreover, in order to weigh the influence of HTLV-II on the natural history of HIV-1 infection, the clinical outcome of HIV-1 disease was compared between subjects with and without HTLV-II coinfection. Our findings showed that HTLV-II does not adversely affect the outcome of HIV-1 infection. Infact, a slower disease progression has been recorded in some HTLV-II coinfected subjects.

Frequent detection of antibodies against HTLV antigens in patients with AIDS-related non-Hodgkin lymphoma

We studied the prevalence of anti-HTLV-I/II antibodies in 22 patients with AIDS-related non-Hodgkin lymphoma (NHL), 453 HIV-1-infected patients without lymphoma (194 of whom were diagnosed as having AIDS), and 6 HIV-1-positive and 75 HIV-1-negative patients with Hodgkin lymphoma. The frequency of serological reactivity against HTLV antigens was significantly higher in the AIDS patients with lymphoma than in those without (8 of 22, 36.4% vs. 20 of 194, 10.3%-p = 0.0027). One of the HIV-1-positive and none of the HIV-1-negative patients with Hodgkin lymphoma showed anti-HTLV-I/II reactivity. Four of the eight seropositive NHL patients showed antibodies directed against HTLV-II recombinant antigens when tested for serological discrimination in a Western blot assay. A PCR study of PBMCs from the only patient with NHL still alive at the time of the study showed HTLV-II-specific sequences in the genomic DNA. These data suggest that HTLV-II or a closely homologous retrovirus infects a high proportion of patients with AIDS-associated NHL.

Presence of human T lymphotropic virus types I and II in Ghana, west Africa

Until recently, HTLV-I was considered to be an Old World virus and HTLV-II was thought to be endemic in the Americas. However, the presence of HTLV-II among Pygmies and other populations of Africa has raised doubts as to whether HTLV-II is primarily a New World virus. The large serosurveys conducted in the urban and rural areas of southern Ghana have identified a 1-2% prevalence for HTLV-I/II. To define the HTLV type, we have used a Western blot assay (HTLV-2.3 blot) that allows simultaneous confirmation and differentiation between HTLVs. Samples (n = 139) were chosen on the basis of previous reactivity with either an enzyme immune assay or r21e-spiked WB results. The WB 2.3 analysis of these specimens identified 55 (40%) to be HTLV positive, 70 (50%) to be HTLV indeterminant, and 14 (10%) to be HTLV negative for HTLV. HTLV seroindeterminant patterns ranged from both gag and env (14 were r21+, p24+, and/or p19+ [all were RIPA negative]) to gag only (21 were p24+/p19+, 16 were p19+, and 7 were p24+), and env only (8 were r21+ and 4 were rgp46+) reactivities. Of the 55 HTLV-positive specimens, 41 were typed as HTLV-I, 9 were HTLV-II, and 5 could not be typed (HTLV-I/II). Of the nine HTLV-II-positive specimens, three were from patients with Burkitt's lymphoma and six were from healthy individuals (two pregnant women) with no obvious risk factors for HTLV-II.(ABSTRACT TRUNCATED AT 250 WORDS)

A multicentric seroepidemiological survey of HTLV-I/II in Italy

BACKGROUND

Several studies carried out in the USA and in Europe have shown the presence of HTLV-I/II antibodies in subjects belonging to high-risk groups for HIV infection as well as blood donors. Concern about the presence of HTLV-I/II markers in the normal population, as well as the efficient transmission of HTLV-I/II by whole blood or infected blood cells have led several countries to include screening for anti-HTLV-I/II among the mandatory serological testing of blood donors.

OBJECTIVE

In order to assess the risk of HTLV-I/II infection related to blood transfusions, a multicentric survey for antibodies against HTLV-I and HTLV-II was carried out involving 10 Italian sites during the spring of 1991.

STUDY DESIGN

Serum specimens were collected from 14,598 blood donors, 1,411 injecting drug users, 1,015 thalassemics, 142 hemophiliacs and 138 hemodialysis patients. HTLV antibodies were detected by a screening EIA which combines a viral lysate with a recombinant HTLV-I env protein (p21e). The serological confirmation was performed by a semi-automated dot-blot immunoassay that detects gag p19 and p24 and env p21e specific antibodies, while the discrimination of HTLV-I and HTLV-II reactivities was carried out by EIAs employing synthetic peptides of the ENV region specific for each virus.

RESULTS

The seroprevalence of confirmed positives was 0.034% among blood donors and 3.61% among IDUs, while no sample of the other categories could be confirmed, although several were indeterminate and one thalassemic reacted against HTLV-I on peptide testing. HTLV-I reactivity was observed in one blood donor, while all 38 of the 51 confirmed seropositive IDU's reacted only to the HTLV-II synthetic peptide.

CONCLUSIONS

These data confirm a high prevalence of HTLV-II among Italian IDUs and show an HTLV-I/II seroprevalence among blood donors very similar to that which was found in the USA volunteer blood donors. A surveillance program among blood donors seems advisable in order to establish the possible need of a mandatory screening for HTLV-I/II.

HTLV-I and -II in intravenous drug users from Sweden and Denmark

693 IVDU (intravenous drug user) sera from Copenhagen, Malmö and Stockholm were tested, 247 retro- and 446 prospectively, for antibodies to human T-lymphotropic virus (HTLV), types I and II, by means of a commercial whole-virus EIA and/or an HTLV-I/-II peptide-based EIA. Positive EIA reactions were checked and typed by electrophoretic immunoblotting, a differential peptide-based EIA and nucleic acid amplification/hybridization with HTLV-I and -II specific primers and probes. 3 (0.7%) of the prospectively tested IVDUs from Malmö, none of 100 from Stockholm and none of 45 from Copenhagen were HTLV-seropositive. The 3 Malmö IVDU cases were a female immigrant from South America, her male native Swedish spouse (both HTLV-I), and a male immigrant Italian heroinist (HTLV-II). We conclude that HTLV was uncommon among intravenous drug users, a sentinel population, in Sweden and Denmark during 1986 and 1989. However, the occurrence of 3 HTLV-positive cases in Malmö 1993 indicates that the situation can change rapidly.

HTLV-II among injecting drug users in Stockholm

134 injecting drug users (IDUs) treated at the Department of Infectious Diseases of Roslagstull Hospital, Stockholm, were tested for antibodies to human T-lymphotropic virus, types I and II, by means of 2 HTLV-I/-II peptide-based enzyme immunoassays (EIAs), followed by a whole-virus EIA. Positive EIA reactions were checked and typed by electrophoretic immunoblotting with native HTLV-I and recombinant HTLV-I and -II proteins. 10 IDUs were diagnosed as HTLV-II seropositive. All 10 were of Scandinavian descent. Thus, like HIV-1, HTLV-II infection has entered the injecting drug user population in Stockholm.