Influenza virus upregulates CXCR4 expression in CD4+ cells

Leishmania donovani and HIV co-infection in vitro: Identification and characterization of main molecular players

The incidence of Leishmania/HIV co-infection is growing and few studies detail the cellular processes and macromolecules participating in co-infection. Thus, the goal of this study was to partially describe the Leishmania/HIV co-infection events by measuring molecular and functional parameters associated with both pathogens in vitro. MT-4 cells (human T-lymphocytes), primary monocytes, and peripheral blood mononuclear cells were exposed to HIV and/or Leishmania donovani. The cytopathic effects generated by the pathogens were observed through microscopy. Viral replication was assessed by monitoring p24 protein levels and parasitic proliferation/infectivity was determined using Giemsa staining. Changes in molecular markers were evaluated by ELISA and fluorescence assays. Our results showed that our system reassembles the main parameters previously described for Leishmania/HIV co-infection in patients in terms of potentiation of parasitic and viral replication/infectivity, amplification of syncytia induction, and alterations of cell viability. In addition, an amplification in NF-κB activation, changes in CXCR4/CCR5 surface expression, and a Th1→Th2 variation in cytokine/chemokine secretion were demonstrated. Altogether, this study could contribute to gain a deep understanding of the molecular events associated with Leishmania/HIV co-infection.

HIV and travel

There is a high demand for travel among HIV-positive individual. This demand arises partly from those who have benefited from advances in antiretroviral therapy as well as those with disease progression. The key to a successful and uneventful holiday lies in careful pre-trip planning, yet many patients fail to obtain advice before travelling. Travel advice for HIV patients is becoming increasingly specialized. In addition to advice on common travel-related infectious diseases, HIV-positive travellers are strongly advised to carry information with them and they need specific advice regarding country entry restrictions, HIV inclusive travel insurance, safety of travel vaccinations and highly active antiretroviral therapy-related issues. A wide range of relevant issues for the HIV-positive traveller are discussed in this review and useful websites can be found at the end.

Distribution of the human immunodeficiency virus coreceptors CXCR4 and CCR5 on leukocytes of persons with human immunodeficiency virus type 1 infection and pulmonary tuberculosis: implications for pathogenesis

Expression of CXCR4 was significantly reduced from normal on all cell subsets of persons with pulmonary tuberculosis (TB group), with HIV-1 infection (HIV group), and those with both infections (HIV/TB group), except for on monocytes in the HIV group. The reductions were most notable in the two TB groups. Interestingly, the duration of antituberculosis treatment was significantly negatively correlated with the expression of CXCR4 on CD4+ and CD8+CD45RO+ cells, monocytes and NK cells, viral load, and proportions of CD38-expressing CD8+ lymphocytes, in HIV/TB patients. By contrast, CCR5 expression on most cell subsets analyzed was increased in all the disease groups, except for on monocytes in the two TB groups. There was no change in CCR5 expression on CD4+ cells when based on the disease groupings. However, higher proportions of CD4+CD45RA+ and CD8+ lymphocytes as well as B cells expressing CCR5 correlated with advancing HIV-1 disease, as did decreased proportions of CXCR4-expressing CD4+CD45RA+ cells.

Transcriptional down-regulation of CXC chemokine receptor 4 induced by impaired association of transcription regulator YY1 with c-Myc in human herpesvirus 6-infected cells

We have recently reported that down-regulation of CXC chemokine receptor (CXCR) 4 in CD4(+) T lymphocytes is induced by human herpesvirus (HHV) 6 infection. In this study, we further studied the mechanisms of HHV-6-induced CXCR4 down-regulation, focusing on the regulation of CXCR4 transcription. Down-regulation of CXCR4 transcription was detected in HHV-6A-infected JJHAN and HHV-6B-infected MT-4 cell lines, as we had previously reported for HHV-6-infected peripheral blood CD4(+) T lymphocytes. Luciferase assays revealed that a YY1-binding site around -320 relative to the transcription start site is important for down-regulation of CXCR4 transcription in HHV-6-infected cells. The binding activity of YY1, which is a repressor of CXCR4 transcription, to the CXCR4 promoter appeared to significantly increase in HHV-6-infected cells compared with the binding activity in mock-infected cells. Immunoprecipitation assays showed that in HHV-6-infected cells association of c-Myc with YY1 was decreased and that of Max with c-Myc was increased, whereas association of Mad with Max appeared to be decreased. The amounts of each of YY1, c-Myc, Max, and Mad proteins synthesized in cells were not altered by HHV-6 infection. These data indicate that the decreased association of YY1 with c-Myc that is caused by impaired interaction in the c-Myc/Max/Mad network results in increased binding activity of YY1 to the CXCR4 promoter, mediating down-regulation of CXCR4 production in HHV-6-infected cells.

The human immunodeficiency virus-infected traveler

As the number of travelers from industrialized countries who are infected with human immunodeficiency virus (HIV) increases as a consequence of the clinical benefits of highly active antiretroviral therapy (HAART), updated prophylactic knowledge is needed. Vaccine prophylaxis must balance the safety and immunogenicity of vaccines with the estimated risk of acquiring the disease. Further research is needed on antimalarial chemoprophylaxis for travelers who are HAART recipients, because of possible pharmacokinetic interactions. Safe sex practices must be adopted to avoid both spreading of the infection in the host country and superinfection with different HIV strains. Most individuals infected with HIV may travel safely, even though the infectious risk has been reported to be higher for patients with advanced infections than for the general population. These patients are also less likely to produce an effective immune response to vaccines. Migrants and refugees from poor countries are also at risk of acquiring HIV infection. Their legal-residency status may often prevent their access to adequate health services, thus necessitating urgent public health actions.