"Candidatus Borrelia kalaharica" Detected from a Febrile Traveller Returning to Germany from Vacation in Southern Africa.

A 26 year-old female patient presented to the Tropical Medicine outpatient unit of the Ludwig Maximilians-University in Munich with febrile illness after returning from Southern Africa, where she contracted a bite by a large mite-like arthropod, most likely a soft-tick. Spirochetes were detected in Giemsa stained blood smears and treatment was started with doxycycline for suspected tick-borne relapsing fever. The patient eventually recovered after developing a slight Jarisch-Herxheimer reaction during therapy. PCR reactions performed from EDTA-blood revealed a 16S rRNA sequence with 99.4% similarity to both, Borrelia duttonii, and B. parkeri. Further sequences obtained from the flagellin gene (flaB) demonstrated genetic distances of 0.066 and 0.097 to B. parkeri and B. duttonii, respectively. Fragments of the uvrA gene revealed genetic distance of 0.086 to B. hermsii in genetic analysis and only distant relations with classic Old World relapsing fever species. This revealed the presence of a novel species of tick-borne relapsing fever spirochetes that we propose to name "Candidatus Borrelia kalaharica", as it was contracted from an arthropod bite in the Kalahari Desert belonging to both, Botswana and Namibia, a region where to our knowledge no relapsing fever has been described so far. Interestingly, the novel species shows more homology to New World relapsing fever Borrelia such as B. parkeri or B. hermsii than to known Old World species such as B. duttonii or B. crocidurae.

Dysfunctional CD8+ T cells in hepatitis B and C are characterized by a lack of antigen-specific T-bet induction.

The transcription factor T-bet regulates the production of interferon-γ and cytotoxic molecules in effector CD8 T cells, and its expression correlates with improved control of chronic viral infections. However, the role of T-bet in infections with differential outcome remains poorly defined. Here, we report that high expression of T-bet in virus-specific CD8 T cells during acute hepatitis B virus (HBV) and hepatitis C virus (HCV) infection was associated with spontaneous resolution, whereas T-bet deficiency was more characteristic of chronic evolving infection. T-bet strongly correlated with interferon-γ production and proliferation of virus-specific CD8 T cells, and its induction by antigen and IL-2 stimulation partially restored functionality in previously dysfunctional T-bet-deficient CD8 T cells. However, restoration of a strong interferon-γ response required additional stimulation with IL-12, which selectively induced the phosphorylation of STAT4 in T-bet(+) CD8 T cells. The observation that T-bet expression rendered CD8 T cells responsive to IL-12 suggests a stepwise mechanism of T cell activation in which T-bet facilitates the recruitment of additional transcription factors in the presence of key cytokines. These findings support a critical role of T-bet for viral clearance and suggest T-bet deficiency as an important mechanism behind chronic infection.

Inhibitory phenotype of HBV-specific CD4+ T-cells is characterized by high PD-1 expression but absent coregulation of multiple inhibitory molecules.

BACKGROUND: T-cell exhaustion seems to play a critical role in CD8+ T-cell dysfunction during chronic viral infections. However, up to now little is known about the mechanisms underlying CD4+ T-cell dysfunction during chronic hepatitis B virus (CHB) infection and the role of inhibitory molecules such as programmed death 1 (PD-1) for CD4+ T-cell failure. METHODS: The expression of multiple inhibitory molecules such as PD-1, CTLA-4, TIM-3, CD244, KLRG1 and markers defining the grade of T-cell differentiation as CCR7, CD45RA, CD57 and CD127 were analyzed on virus-specific CD4+ T-cells from peripheral blood using a newly established DRB1*01-restricted MHC class II Tetramer. Effects of in vitro PD-L1/2 blockade were defined by investigating changes in CD4+ T-cell proliferation and cytokine production. RESULTS: CD4+ T-cell responses during chronic HBV infection was characterized by reduced Tetramer+CD4+ T-cell frequencies, effector memory phenotype, sustained PD-1 but low levels of CTLA-4, TIM-3, KLRG1 and CD244 expression. PD-1 blockade revealed individualized patterns of in vitro responsiveness with partly increased IFN-γ, IL-2 and TNF-α secretion as well as enhanced CD4+ T-cell expansion almost in treated patients with viral control. CONCLUSION: HBV-specific CD4+ T-cells are reliably detectable during different courses of HBV infection by MHC class II Tetramer technology. CD4+ T-cell dysfunction during chronic HBV is basically linked to strong PD-1 upregulation but absent coregulation of multiple inhibitory receptors. PD-L1/2 neutralization partly leads to enhanced CD4+ T-cell functionality with heterogeneous patterns of CD4+ T-cell rejunivation.

Inhibitory molecules that regulate expansion and restoration of HCV-specific CD4+ T cells in patients with chronic infection.

BACKGROUND & AIMS: Inhibitory receptors such as programmed death 1 (PD-1) and cytotoxic T lymphocyte-associated antigen (CTLA)-4 mediate CD8+ T-cell exhaustion during chronic viral infection, but little is known about roles in dysfunction of CD4+ T cells. METHODS: We investigated the functions of inhibitory molecules on hepatitis C virus (HCV)-, influenza-, and Epstein-Barr virus (EBV)-specific CD4+ T cells in patients with chronic infections compared with patients with resolved HCV infection and healthy donors. Expression of PD-1, CTLA-4, CD305, and CD200R were analyzed on HCV-specific CD4+ T cells, isolated from peripheral blood using major histocompatibility complex class II tetramers. We investigated the effects of in vitro inhibition of various inhibitory pathways on proliferation and cytokine production by CD4+ T cells, and we compared these effects with those from inhibition of interleukin (IL)-10 and transforming growth factor (TGF)-ß1. RESULTS: PD-1 and CTLA-4 were up-regulated on virus-specific CD4+ T cells from patients with chronic HCV infections. PD-1 expression was lower on influenza- than on HCV-specific CD4+ T cells from subjects with chronic HCV infection, whereas CTLA-4 was expressed at similar levels, independent of their specificity. CD305 and CD200R were up-regulated in HCV resolvers. Blockade of PD-L1/2, IL-10, and TGF-ß1 increased expansion of CD4+ T cells in patients with chronic HCV, whereas inhibition of IL-10 and TGF-ß1 was most effective in restoring HCV-specific production of interferon gamma, IL-2, and tumor necrosis factor α. CONCLUSIONS: We characterized expression of inhibitory molecules on HCV-, influenza-, and EBV-specific CD4+ T cells and the effects of in vitro blockade on CD4+ T-cell expansion and cytokine production. Inhibition of PD-1, IL-10, and TGF-ß1 is most efficient in restoration of HCV-specific CD4+ T cells.

The immunoregulatory role of CD244 in chronic hepatitis B infection and its inhibitory potential on virus-specific CD8+ T-cell function.

UNLABELLED: Multiple inhibitory receptors may play a role in the weak or absent CD8+ T-cell response in chronic hepatitis B virus (HBV) infection. Yet few receptors have been characterized in detail and little is known about their complex regulation. In the present study, we investigated the role of the signaling lymphocyte activation molecule (SLAM)-related receptor CD244 and of programmed death 1 (PD-1) in HBV infection in 15 acutely and 66 chronically infected patients as well as 9 resolvers and 21 healthy controls. The expression of CD244, PD-1, and T-cell immunoglobulin domain and mucin domain 3 (TIM-3) was analyzed in virus-specific CD8+ T-cells derived from peripheral blood or liver using major histocompatibility complex class I pentamers targeting immunodominant epitopes of HBV, Epstein-Barr-virus (EBV), or influenza virus (Flu). In chronic HBV infection, virus-specific CD8+ T-cells expressed higher levels of CD244 both in the peripheral blood and liver in comparison to the acute phase of infection or following resolution. CD244 was expressed at similarly high levels in EBV infection, but was low on Flu-specific CD8+ T-cells. In chronic HBV infection, high-level CD244 expression coincided with an increased expression of PD-1. The inhibition of the CD244 signaling pathway by antibodies directed against either CD244 or its ligand CD48 resulted in an increased virus-specific proliferation and cytotoxicity as measured by the expression of CD107a, interferon-γ, and tumor necrosis factor-α in CD8+ T-cells. CONCLUSION: CD244 and PD-1 are highly coexpressed on virus-specific CD8+ T-cells in chronic HBV infection and blocking CD244 or its ligand CD48 may restore T-cell function independent of the PD-1 pathway. CD244 may thus be another potential target for immunotherapy in chronic viral infections.

Risk Factors and predictors of human immunodeficiency virus infection among injection drug users.

BACKGROUND/AIM: Injection drug users (IDUs) have a high risk of acquiring an infection with the human immunodeficiency virus (HIV). To improve counseling and prevention, a better understanding of risk factors and predictors for an infection must be gained. This retrospective study has the aim to determine the risk factors for acquisition of HIV infection other than sharing of needles/syringes. METHODS: The study population consisted of all patients admitted to the detoxification unit between 1991 and 1996 who met ICD-10 criteria for opioid dependency, who reported to share needles, and who agreed to have an antibody test. Possible risk factors were assessed by interview. Cross tables based on bivariate logistic regression were constructed to estimate the relative odds. Multiple logistic regression modeling procedures were used to adjust possible confounding factors. RESULTS: A total of 1,049 out of 1,656 patients admitted were included into the study. 4.8% of the patients were HIV-1 seropositive. The prevalence was higher among older patients and among patients living with a significant other substance drug user with substance dependency, after a longer duration of drug use, and after coinfection with hepatitis B virus and/or hepatitis C virus (HCV). Using multiple logistic regression analyses and including all individually significant risk factors, we found only coinfection with HCV to remain significant. 92% of the HIV-infected patients were also HCV infected. In the group younger than 23 years of age, a total of 53.5% of the IDUs were still seronegative for HIV, hepatitis A and B virus, and HCV. CONCLUSIONS: Despite the high rate of HCV coinfection (92%) in HIV-infected patients, we found more than 50% of IDUs younger than 23 years to be neither infected with HCV nor with HIV. Early prevention strategies against infectious diseases should especially focus on young IDUs.

Plasmacytoid dendritic cells in acute and chronic hepatitis C virus infection.

Chronic evolution of acute hepatitis C (aHC) occurs in more than 80% of patients but can frequently be prevented by early treatment with interferon (IFN)-alpha. Plasmacytoid dendritic cells (pDCs) are the major endogenous IFN-alpha producers, but their role in aHC is unknown. In this study, frequency, phenotype, and pDC function were analyzed in 13 patients with aHC and 32 patients with chronic hepatitis C (cHC) compared with 20 healthy controls, 33 sustained responders to antiviral treatment, 14 patients with acute hepatitis B (aHB), and 21 patients with nonviral inflammatory disease. In aHC, pDCs in the peripheral blood were significantly reduced compared with healthy controls (median, 0.1% vs. 0.36%, P < .0005) and were inversely correlated to alanine aminotransferase levels (r = -0.823; P < .005). Circulating pDCs in aHC were immature, as determined via reduced expression of HLA-DR and CCR7, and produced little amounts of IFN-alpha (median, 3.5 pg/50,000 peripheral blood mononuclear cells [PBMCs] vs. 498.4 pg/50,000 PBMCs in healthy controls; P < .0005). Less pronounced changes were present in cHC (median, 0.17%, 28.0 pg/50,000 PBMCs IFN-alpha, respectively). However, a significantly reduced frequency and IFN-alpha production was also found in self-limited aHB (median 0.1%, 8.6 pg/50,000 PBMCs) and in patients with nonviral inflammatory disease (median 0.19%, 7.5 pg/50,000 PBMCs). In conclusion, in aHC frequency and IFN-alpha-producing capacity of peripheral blood pDCs are dramatically reduced and inversely correlated with the degree of liver inflammation. In cHC there is incomplete recovery of pDC function, which, however, could be solely due to the chronic inflammatory state.

Hepatitis C virus infection in injection drug users in Bavaria: risk factors for seropositivity.

BACKGROUND: Hepatitis C Virus (HCV) infection is the most common disease among intravenous drug users (IDUs). PATIENTS AND METHOD: All patients admitted to the detoxification unit 1991-1997 and meeting ICD-10 diagnosis of opioid dependency were tested for anti-HCV serology. RESULTS: Thousand and forty nine patients were included in the study. About 61.3% of the IDUs were anti-HCV positive. Increasing age (PR: 1.46; 95% CI: 1.34-1.60), living with a significant other drug user (PR: 1.17; 95% CI: 1.05-1.31), history of therapy (PR: 1.62; 95% CI: 1.50-1.74), history of imprisonment (PR: 1.48; 95% CI: 1.36-1.61), history of emergency treatment (PR: 1.23; 95% CI: 1.12-1.35), additional daily consumption of benzodiazepines (PR: 1.10; 95% CI: 1.00-2.21) or alcohol (PR: 1.26; 95% CI: 1.14-1.38), frequency of injecting heroin (daily: PR: 0.86; 95% CI: 0.78-0.96; previously: PR: 1.14; 95% CI: 1.03-1.26) and type of opioid dependency (methadone: PR: 1.26; 95% CI: 1.13-1.41) were significant factors, considered as individual factors, for positive anti-HCV serology. Using multiple logistic regression we found that older age (OR: 3.54, 95% CI: 1.30-9.67), longer duration of opioid use (OR: 5.74; 95% CI: 1.82-18.13), living with a significant other drug user (OR: 1.47; 95% CI: 1.01-2.16), history of therapy (OR: 4.87; 95% CI: 1.67-14.20), history of imprisonment (OR: 1.92; 95% CI: 1.12-3.28), history of emergency treatment (OR: 1.45; 95% CI: 1.06-1.99) and additional daily consumption of alcohol (OR: 1.49; 95% CI: 1.04-2.13) remained independently associated with positive anti-HCV serology. CONCLUSIONS: These data support the need for early prevention strategies, namely, education of teachers in schools and further training of counsellors informing IDUs of what they can do to minimise the risk of becoming infected or of transmitting infectious agents to others.

Hepatitis C virus eradication associated with hepatitis B virus superinfection and development of a hepatitis B virus specific T cell response.

BACKGROUND/AIMS: Specific T cell responses during acute hepatitis B and during chronic hepatitis C have been described in detail. However, the T cell responses during the rare setting of acute hepatitis B virus (HBV) infection in the course of chronic hepatitis C that eventually lead to clearance of both viruses are completely unknown. METHODS: We analyzed the virus specific CD4+ and CD8+ T cell response during an acute HBV superinfection in a patient with chronic hepatitis C. RESULTS: The patient eliminated hepatitis C virus (HCV)-RNA and HBV-DNA from serum soon after the clinical onset of acute hepatitis B. The HBV specific T cell response found in this patient corresponds to the typical response that has been described in acute hepatitis B without chronic HCV infection. In contrast the hepatitis C specific immune response was similar to that generally found in chronic hepatitis C despite the fact that the patient also eliminated HCV-RNA. CONCLUSIONS: We hypothesize that the acute HBV infection induced a HBV specific T cell response which was associated with elimination HBV DNA and HCV-RNA, the latter possibly by bystander mechanisms, e.g. via secretion of cytokines. If such a non-specific bystander mechanism which has proven to be effective in the experimental setting and which is formally described here for a single patient can be shown to be a more general phenomenon, it may support the approach with new antiviral strategies, e.g. the induction of non-specific defense mechanisms against HCV.