At the end of 2005, an outbreak of fever associated with joint pain occurred in La Réunion. The causal agent, chikungunya virus (CHIKV), has been known for 50 years and could thus be readily ...identified. This arbovirus is present worldwide, particularly in India, but also in Europe, with new variants returning to Africa. In humans, it causes a disease characterized by a typical acute infection, sometimes followed by persistent arthralgia and myalgia lasting months or years. Investigations in the La Réunion cohort and studies in a macaque model of chikungunya implicated monocytes-macrophages in viral persistence. In this Review, we consider the relationship between CHIKV and the immune response and discuss predictive factors for chronic arthralgia and myalgia by providing an overview of current knowledge on chikungunya pathogenesis. Comparisons of data from animal models of the acute and chronic phases of infection, and data from clinical series, provide information about the mechanisms of CHIKV infection-associated inflammation, viral persistence in monocytes-macrophages, and their link to chronic signs.
Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that induces in humans a disease characterized by fever, rash, and pain in muscles and joints. The recent emergence or reemergence of CHIKV in ...the Indian Ocean Islands and India has stressed the need to better understand the pathogenesis of this disease. Previous CHIKV disease models have used young or immunodeficient mice, but these do not recapitulate human disease patterns and are unsuitable for testing immune-based therapies. Herein, we describe what we believe to be a new model for CHIKV infection in adult, immunocompetent cynomolgus macaques. CHIKV infection in these animals recapitulated the viral, clinical, and pathological features observed in human disease. In the macaques, long-term CHIKV infection was observed in joints, muscles, lymphoid organs, and liver, which could explain the long-lasting CHIKV disease symptoms observed in humans. In addition, the study identified macrophages as the main cellular reservoirs during the late stages of CHIKV infection in vivo. This model of CHIKV physiopathology should allow the development of new therapeutic and/or prophylactic strategies.
Malaria relapses, resulting from the activation of quiescent hepatic hypnozoites of Plasmodium vivax and Plasmodium ovale, hinder global efforts to control and eliminate malaria. As primaquine, the ...only drug capable of eliminating hypnozoites, is unsuitable for mass administration, an alternative drug is needed urgently. Currently, analyses of hypnozoites, including screening of compounds that would eliminate them, can only be made using common macaque models, principally Macaca rhesus and Macaca fascicularis, experimentally infected with the relapsing Plasmodium cynomolgi. Here, we present a protocol for long-term in vitro cultivation of P. cynomolgi-infected M. fascicularis primary hepatocytes during which hypnozoites persist and activate to resume normal development. In a proof-of-concept experiment, we obtained evidence that exposure to an inhibitor of histone modification enzymes implicated in epigenetic control of gene expression induces an accelerated rate of hypnozoite activation. The protocol presented may further enable investigations of hypnozoite biology and the search for compounds that kill hypnozoites or disrupt their quiescence.
In vivo electroporation (EP) is used to enhance the uptake of nucleic acids and its association with DNA vaccination greatly stimulates immune responses to vaccine antigens delivered through the ...skin. However, the effect of EP on cutaneous cell behavior, the dynamics of immune cell recruitment and local inflammatory factors, have not been fully described. Here, we show that intradermal DNA vaccination combined with EP extends antigen expression to the epidermis and the subcutaneous skin muscle in non-human primates. In vivo fibered confocal microscopy and dynamic ex vivo imaging revealed that EP promotes the mobility of Langerhans cells (LC) and their interactions with transfected cells prior to their migration from the epidermis. At the peak of vaccine expression, we detected antigen in damaged keratinocyte areas in the epidermis and we characterized recruited immune cells in the skin, the hypodermis and the subcutaneous muscle. EP alone was sufficient to induce the production of pro-inflammatory cytokines in the skin and significantly increased local concentrations of Transforming Growth Factor (TGF)-alpha and IL-12. Our results show the kinetics of inflammatory processes in response to EP of the skin, and reveal its potential as a vaccine adjuvant.
Neutralizing antibodies directed against adeno-associated virus (AAV) are commonly found in humans. In seropositive subjects, vector administration is not feasible as antibodies neutralize AAV ...vectors even at low titers. Consequently, a relatively large proportion of humans is excluded from enrollment in clinical trials and, similarly, vector redosing is not feasible because of development of high-titer antibodies following AAV vector administration. Plasmapheresis has been proposed as strategy to remove anti-AAV antibodies from the bloodstream. Although safe and relatively effective, the technology has some limitations mainly related to the nonspecific removal of all circulating IgG. Here we developed an AAV-specific plasmapheresis column which was shown to efficiently and selectively deplete anti-AAV antibodies without depleting the total immunoglobulin pool from plasma. We showed the nearly complete removal of anti-AAV antibodies from high titer purified human IgG pools and plasma samples, decreasing titers to levels that allow AAV vector administration in mice. These results provide proof-of-concept of a method for the AAV-specific depletion of neutralizing antibodies in the setting of in vivo gene transfer.
Abstract
Motivation
Flow and mass cytometry are experimental techniques used to measure the level of proteins expressed by cells at the single-cell resolution. Several algorithms were developed in ...flow cytometry to increase the number of simultaneously measurable markers. These approaches aim to combine phenotypic information of different cytometric profiles obtained from different cytometry panels.
Results
We present here a new algorithm, called CytoBackBone, which can merge phenotypic information from different cytometric profiles. This algorithm is based on nearest-neighbor imputation, but introduces the notion of acceptable and non-ambiguous nearest neighbors. We used mass cytometry data to illustrate the merging of cytometric profiles obtained by the CytoBackBone algorithm.
Availability and implementation
CytoBackBone is implemented in R and the source code is available at https://github.com/tchitchek-lab/CytoBackBone.
Supplementary information
Supplementary data are available at Bioinformatics online.
Natural killer (NK) cells play a critical understudied role during HIV infection in tissues. In a natural host of SIV, the African green monkey (AGM), NK cells mediate a strong control of SIVagm ...infection in secondary lymphoid tissues. We demonstrate that SIVagm infection induces the expansion of terminally differentiated NKG2a
NK cells in secondary lymphoid organs displaying an adaptive transcriptional profile and increased MHC-E-restricted cytotoxicity in response to SIV Env peptides while expressing little IFN-γ. Such NK cell differentiation was lacking in SIVmac-infected macaques. Adaptive NK cells displayed no increased NKG2C expression. This study reveals a previously unknown profile of NK cell adaptation to a viral infection, thus accelerating strategies toward NK-cell directed therapies and viral control in tissues.
IFN-I production is a characteristic of HIV/SIV primary infections. However, acute IFN-I plasma concentrations rapidly decline thereafter. Plasmacytoid dendritic cells (pDC) are key players in this ...production but primary infection is associated with decreased responsiveness of pDC to TLR 7 and 9 triggering. IFNα production during primary SIV infection contrasts with increased pDC death, renewal and dysfunction. We investigated the contribution of pDC dynamics to both acute IFNα production and the rapid return of IFNα concentrations to pre-infection levels during acute-to-chronic transition. Nine cynomolgus macaques were infected with SIVmac251 and IFNα-producing cells were quantified and characterized. The plasma IFN-I peak was temporally associated with the presence of IFNα(+) pDC in tissues but IFN-I production was not detectable during the acute-to-chronic transition despite persistent immune activation. No IFNα(+) cells other than pDC were detected by intracellular staining. Blood-pDC and peripheral lymph node-pDC both lost IFNα(-) production ability in parallel. In blood, this phenomenon correlated with an increase in the counts of Ki67(+)-pDC precursors with no IFNα production ability. In tissues, it was associated with increase of both activated pDC and KI67(+)-pDC precursors, none of these being IFNα(+) in vivo. Our findings also indicate that activation/death-driven pDC renewal rapidly blunts acute IFNα production in vivo: pDC sub-populations with no IFNα-production ability rapidly increase and shrinkage of IFNα production thus involves both early pDC exhaustion, and increase of pDC precursors.
PDF
