MHC class II-deficient mice allow functional human CD4+ T-cell development.

Humanized mouse models have been developed to study cell-mediated immune responses to human pathogens in vivo. How immunocompetent human T cells are selected in a murine thymus in such humanized mice remains poorly explored. To gain insights into this mechanism, we investigated the differentiation of human immune compartments in mouse MHC class II-deficient immune-compromised mice (humanized Ab0 mice). We observed a strong reduction in human CD4+ T-cell development but despite this reduction Ab0 mice had no disadvantage during Epstein-Barr virus (EBV) infection. Viral loads were equally well controlled in humanized Ab0 mice compared to humanized NSG mice, and improved T-cell recognition of autologous EBV-transformed B cells was observed, especially with respect to cytotoxicity. MHC class II blocking experiments with CD4+ T cells from humanized Ab0 mice demonstrated MHC class II restriction of lymphoblastoid cell line recognition. These findings suggest that a small number of CD4+ T cells in humanized mice can be solely selected on human MHC class II molecules, presumably expressed by reconstituted human immune cells, leading to improved effector functions.

KSHV infection of B cells primes protective T cell responses in humanized mice.

Kaposi sarcoma associated herpesvirus (KSHV) is associated with around 1% of all human tumors, including the B cell malignancy primary effusion lymphoma (PEL), in which co-infection with the Epstein Barr virus (EBV) can almost always be found in malignant cells. Here, we demonstrate that KSHV/EBV co-infection of mice with reconstituted human immune systems (humanized mice) leads to IgM responses against both latent and lytic KSHV antigens, and expansion of central and effector memory CD4+ and CD8+ T cells. Among these, KSHV/EBV dual-infection allows for the priming of CD8+ T cells that are specific for the lytic KSHV antigen K6 and able to kill KSHV/EBV infected B cells. This suggests that K6 may represent a vaccine antigen for the control of KSHV and its associated pathologies in high seroprevalence regions, such as Sub-Saharan Africa.

Co-Infection of the Epstein-Barr Virus and the Kaposi Sarcoma-Associated Herpesvirus.

The two human tumor viruses, Epstein-Barr virus (EBV) and Kaposi sarcoma-associated herpesvirus (KSHV), have been mostly studied in isolation. Recent studies suggest that co-infection with both viruses as observed in one of their associated malignancies, namely primary effusion lymphoma (PEL), might also be required for KSHV persistence. In this review, we discuss how EBV and KSHV might support each other for persistence and lymphomagenesis. Moreover, we summarize what is known about their innate and adaptive immune control which both seem to be required to ensure asymptomatic persistent co-infection with these two human tumor viruses. A better understanding of this immune control might allow us to prepare for vaccination against EBV and KSHV in the future.

KSHV infection drives poorly cytotoxic CD56-negative natural killer cell differentiation in vivo upon KSHV/EBV dual infection.

Herpesvirus infections shape the human natural killer (NK) cell compartment. While Epstein-Barr virus (EBV) expands immature NKG2A+ NK cells, human cytomegalovirus (CMV) drives accumulation of adaptive NKG2C+ NK cells. Kaposi sarcoma-associated herpesvirus (KSHV) is a close relative of EBV, and both are associated with lymphomas, including primary effusion lymphoma (PEL), which nearly always harbors both viruses. In this study, KSHV dual infection of mice with reconstituted human immune system components leads to the accumulation of CD56-CD16+CD38+CXCR6+ NK cells. CD56-CD16+ NK cells were also more frequently found in KSHV-seropositive Kenyan children. This NK cell subset is poorly cytotoxic against otherwise-NK-cell-susceptible and antibody-opsonized targets. Accordingly, NK cell depletion does not significantly alter KSHV infection in humanized mice. These data suggest that KSHV might escape NK-cell-mediated immune control by driving CD56-CD16+ NK cell differentiation.

Increased Azithromycin Susceptibility of Multidrug-Resistant Gram-Negative Bacteria on RPMI-1640 Agar Assessed by Disk Diffusion Testing.

Increasing antibiotic resistances and a lack of new antibiotics render the treatment of Gram-negative bacterial infections increasingly difficult. Therefore, additional approaches are being investigated. Macrolides are not routinely used against Gram-negative bacteria due to lack of evidence of in vitro effectiveness. However, it has been shown that Pseudomonas spp. are susceptible to macrolides in liquid RPMI-1640 and clinical data suggest improvement in patients' outcomes. So far, these findings have been hardly applicable to the clinical setting due to lack of routine low-complexity antimicrobial susceptibility testing (AST) for macrolides. We therefore optimized and compared broth microdilution and disk diffusion AST. Multidrug-resistant Gram-negative bacteria (Escherichia coli, Enterobacter cloacae, Klebsiella pneumoniae, Pseudomonas aeruginosa) were tested for azithromycin susceptibility by disk diffusion and broth microdilution in Mueller-Hinton and RPMI-1640 media. Azithromycin susceptibility of Enterobacteriaceae and a subgroup of P. aeruginosa increased significantly on RPMI-1640 agar compared to Mueller-Hinton agar. Further, a significant correlation (Kendall, τ, p) of zone diameters and minimal inhibitory concentrations (MICs) was found on RPMI-1640 agar for E. coli (-0.4279, 0.0051), E. cloacae (-0.3783, 0.0237) and P. aeruginosa (-0.6477, <0.0001). Performing routine disk diffusion AST on RPMI-1640 agar may lead to the identification of additional therapeutic possibilities for multidrug-resistant bacterial infections in the routine clinical diagnostic setting.

Rinosporidiose da conjuntiva: relato de caso / Rhinosporidiosis of the conjunctiva: case report

A rinosporidiose é infecção fúngica rara, especialmente quando compromete o olho. O agente etiológico é o Rhinosporidium seeberi, que produz lesões elevadas e polipóides, com característica de inflamação granulomatosa, rica em parasitos. Os autores relatam um caso de comprometimento da conjuntiva tarsal em paciente jovem de 22 anos. + o primeiro caso de rinosporidiose ocular no estado do Espírito Santo comprometendo o olho. As características clínicas, a etiologia, a patogênese, o diagnóstico e a terapêutica são discutidos.