Wk Postinfection Research Articles

NK Cell and Monocyte Dysfunction in Multisystem Inflammatory Syndrome in Children.

Multisystem inflammatory syndrome in children (MIS-C) is a severe complication of SARS-CoV-2 infection characterized by multiorgan involvement and inflammation. Testing of cellular function ex vivo to understand the aberrant immune response in MIS-C is limited. Despite strong Ab production in MIS-C, SARS-CoV-2 nucleic acid testing can remain positive for 4-6 wk postinfection. Therefore, we hypothesized that dysfunctional cell-mediated Ab responses downstream of Ab production may be responsible for delayed clearance of viral products in MIS-C. In MIS-C, monocytes were hyperfunctional for phagocytosis and cytokine production, whereas NK cells were hypofunctional for both killing and cytokine production. The decreased NK cell cytotoxicity correlated with an NK exhaustion marker signature and systemic IL-6 levels. Potentially providing a therapeutic option, cellular engagers of CD16 and SARS-CoV-2 proteins were found to rescue NK cell function invitro. Taken together, our results reveal dysregulation in Ab-mediated cellular responses of myeloid and NK cells that likely contribute to the immune pathology of this disease.

Infection with Ascaridia galli Does Not Significantly Alter Intestinal Microbiota and Is Cleared After Changes in the Expression of Cytokines.

Because of the trend of cage-free egg production, infections with the nematode Ascaridia galli are receiving increased attention. The aim of this study was to establish a timeline for the influence of A. galli on the expression of key cytokines related to a parasitic immune response, and on the composition of the jejunal microbiota. Twenty-eight male layer-type birds were challenged at 24, 25, and 26 days of age. An additional 28 birds were kept as uninfected controls. Starting on Day 31, three birds of each group were euthanized every week until 8 wk postinfection (PI). The number of larvae isolated from the intestinal wall decreased over time, until no larvae were seen at 7 and 8 wk PI. At 5 wk PI, there was a numerical upregulation of all cytokines (TGF-β, IFN-γ, IL-4, IL-8, IL-10, IL-13) in the infected group, but this change was only statistically significant for IL-13. At this time point, larvae were expected to have developed into adults that would have shed eggs in the feces. However, no adult worms were seen and there was no egg shedding. For the microbiota analysis, there were significant differences in the alpha diversity (Faith's phylogenetic diversity) between challenge and control groups, and the beta diversity analysis showed slight differences between samples, suggesting that the age of the birds was the main reason for the separation of groups. These findings suggest that the upregulation of all cytokines evaluated in Week 5 might be the reason for resolution of the infection. Possible explanations are that a high infection dose and the fact that birds were fed with a more nutritionally dense feed might have contributed to the birds' immune system clearing the infection before the worms were able to reach maturity.

TSLP-Driven Chromatin Remodeling and Trained Systemic Immunity after Neonatal Respiratory Viral Infection.

Our studies have previously shown a role for persistent TSLP production in the lungs of mice after early-life respiratory syncytial virus (RSV) infection that leads to an altered immune phenotype, including accumulation of "inflammatory" dendritic cells (DC). This study investigates the role of TSLP driving systemic trained immunity in DC in early-life RSV-infected mice. Bone marrow-derived DCs (BMDC) from early-life RSV-infected mice at 4 wk postinfection showed enhanced expression of costimulatory molecules and cytokines, including Tslp, that regulate immune cell function. The adoptive transfer of BMDC grown from early-life RSV-infected mice was sufficient to exacerbate allergic disease development. The addition of recombinant TSLP during differentiation of BMDC from naive mice induced a similar altered phenotype as BMDC grown from early-life RSV-infected mice, suggesting a role for TSLP in the phenotypic changes. To assess the role of TSLP in these changes, global transcriptomic characterization of TSLPR-/- BMDC infected with RSV was performed and showed a higher upregulation of type 1 IFN genes and concomitant downregulation of inflammatory genes. Assay for transposase-accessible chromatin using sequencing analysis demonstrated that TSLPR-/- BMDC had a parallel gain in physical chromatin accessibility near type 1 genes and loss in accessibility near genes related to RSV pathology, with IFN regulatory factor 4 (IRF4) and STAT3 predicted as top transcription factors binding within differentially accessible regions in wild-type. Importantly, these studies show that in the absence of TSLP signaling, BMDC are able to mount an appropriate type 1 IFN-associated antiviral response to RSV. In summary, RSV-induced TSLP alters chromatin structure in DC to drive trained innate immunity and activates pathogenic gene programs in mice.

Quantification of Brucella abortus population structure in a natural host

Cattle are natural hosts of the intracellular pathogen Brucella abortus, which inflicts a significant burden on the health and reproduction of these important livestock. The primary routes of infection in field settings have been described, but it is not known how the bovine host shapes the structure of B. abortus populations during infection. We utilized a library of uniquely barcoded B. abortus strains to temporally and spatially quantify population structure during colonization of cattle through a natural route of infection. Introducing 108 bacteria from this barcoded library to the conjunctival mucosa resulted in expected levels of local lymph node colonization at a 1-wk time point. We leveraged variance in strain abundance in the library to demonstrate that only 1 in 10,000 brucellae introduced at the site of infection reached a parotid lymph node. Thus, cattle restrict the overwhelming majority of B. abortus introduced via the ocular conjunctiva at this dose. Individual strains were spatially restricted within the host tissue, and the total B. abortus census was dominated by a small number of distinct strains in each lymph node. These results define a bottleneck that B. abortus must traverse to colonize local lymph nodes from the conjunctival mucosa. The data further support a model in which a small number of spatially isolated granulomas founded by unique strains are present at 1 wk postinfection. These experiments demonstrate the power of barcoded transposon tools to quantify infection bottlenecks and to define pathogen population structure in host tissues.

HIGH PREVALENCE OF CIRCULATING ANTIBODIES TO RENIBACTERIUM SALMONINARUM IN SPAWNING ONCORHYNCHUS SPP. FROM LAKE MICHIGAN, USA.

Bacterial kidney disease, caused by Renibacterium salmoninarum, threatens salmonids worldwide. Following devastating mortality episodes in Oncorhynchus spp. in Lake Michigan, US, in the 1980s and infection rates >90%, pathogen prevalence has steadily declined to <5% over three decades in the three state-managed stocks. In this study, we sought to determine if the declining infection rates were associated with heightened circulating antibodies in state-managed Oncorhynchus spp. residing in the Lake Michigan watershed. A single-dilution, indirect enzyme-linked immunosorbent assay (ELISA) was modified to detect circulating antibodies against R. salmoninarum. Baseline values were delineated from naive chinook salmon (Oncorhynchus tshawytscha) and rainbow trout (Oncorhynchus mykiss). The assay was first used to assess primary antibody production over a 4-wk period in chinook salmon experimentally infected with R. salmoninarum. Mean antibody response was detected as early as 2 wk postinfection and continued to increase to the end of the observation period. The modified ELISA was then used to detect antibodies in serum samples collected from feral adult chinook salmon, coho salmon (Oncorhynchus kisutch), and steelhead trout (O. mykiss) returning to spawn at Lake Michigan weirs in 2009 and 2013. Results demonstrated that about 80% of feral Oncorhynchus spp. had measurable titers of circulating antibodies to R. salmoninarum. The relative ease and reasonable costs of this modified ELISA makes it a valuable serosurveillance tool for assessing the humoral immune status of feral salmonid populations.

Canine olfactory detection of a vectored phytobacterial pathogen, Liberibacter asiaticus, and integration with disease control

Early detection and rapid response are crucial to avoid severe epidemics of exotic pathogens. However, most detection methods (molecular, serological, chemical) are logistically limited for large-scale survey of outbreaks due to intrinsic sampling issues and laboratory throughput. Evaluation of 10 canines trained for detection of a severe exotic phytobacterial arboreal pathogen, Candidatus Liberibacter asiaticus (CLas), demonstrated 0.9905 accuracy, 0.8579 sensitivity, and 0.9961 specificity. In a longitudinal study, cryptic CLas infections that remained subclinical visually were detected within 2 wk postinfection compared with 1 to 32 mo for qPCR. When allowed to interrogate a diverse range of in vivo pathogens infecting an international citrus pathogen collection, canines only reacted to Liberibacter pathogens of citrus and not to other bacterial, viral, or spiroplasma pathogens. Canines trained to detect CLas-infected citrus also alerted on CLas-infected tobacco and periwinkle, CLas-bearing psyllid insect vectors, and CLas cocultured with other bacteria but at CLas titers below the level of molecular detection. All of these observations suggest that canines can detect CLas directly rather than only host volatiles produced by the infection. Detection in orchards and residential properties was real time, ∼2 s per tree. Spatiotemporal epidemic simulations demonstrated that control of pathogen prevalence was possible and economically sustainable when canine detection was followed by intervention (i.e., culling infected individuals), whereas current methods of molecular (qPCR) and visual detection failed to contribute to the suppression of an exponential trajectory of infection.

IL-10 Impairs Local Immune Response in Lung Granulomas and Lymph Nodes during Early Mycobacterium tuberculosis Infection.

Tuberculosis (TB), caused by Mycobacterium tuberculosis, continues to be a major global health problem. Lung granulomas are organized structures of host immune cells that function to contain the bacteria. Cytokine expression is a critical component of the protective immune response, but inappropriate cytokine expression can exacerbate TB. Although the importance of proinflammatory cytokines in controlling M. tuberculosis infection has been established, the effects of anti-inflammatory cytokines, such as IL-10, in TB are less well understood. To investigate the role of IL-10, we used an Ab to neutralize IL-10 in cynomolgus macaques during M. tuberculosis infection. Anti-IL-10-treated nonhuman primates had similar overall disease outcomes compared with untreated control nonhuman primates, but there were immunological changes in granulomas and lymph nodes from anti-IL-10-treated animals. There was less thoracic inflammation and increased cytokine production in lung granulomas and lymph nodes from IL-10-neutralized animals at 3-4 wk postinfection compared with control animals. At 8 wk postinfection, lung granulomas from IL-10-neutralized animals had reduced cytokine production but increased fibrosis relative to control animals. Although these immunological changes did not affect the overall disease burden during the first 8 wk of infection, we paired computational modeling to explore late infection dynamics. Our findings support that early changes occurring in the absence of IL-10 may lead to better bacterial control later during infection. These unique datasets provide insight into the contribution of IL-10 to the immunological balance necessary for granulomas to control bacterial burden and disease pathology in M. tuberculosis infection.

Abortive herpes simplex virus infection of nonneuronal cells results in quiescent viral genomes that can reactivate

Abortive viral infections are usually studied in populations of susceptible but nonpermissive cells. Single-cell studies of viral infections have demonstrated that even in susceptible and permissive cell populations, abortive infections can be detected in subpopulations of the infected cells. We have previously identified abortive infections in HeLa cells infected with herpes simplex virus 1 (HSV-1) at high multiplicity of infection (MOI). Here, we tested 4 additional human-derived nonneuronal cell lines (cancerous or immortalized) and found significant subpopulations that remain abortive. To characterize these abortive cells, we recovered cell populations that survived infection with HSV-1 at high MOI. The surviving cells retained proliferative potential and the ability to be reinfected. These recovered cell populations maintained the viral genomes in a quiescent state for at least 5 wk postinfection. Our results indicate that these viral genomes are maintained inside the nucleus, bound to cellular histones and occasionally reactivated to produce new progeny viruses. We conclude that abortive HSV-1 infection is a common feature during infection of nonneuronal cells and results in a latency-like state in the infected cells. Our findings question the longstanding paradigm that alphaherpesviruses can establish spontaneous latency only in neuronal cells and emphasize the stochastic nature of lytic versus latency decision of HSV-1 in nonneuronal cells.

A Subset of Mycobacteria-Specific CD4+ IFN-γ+ T Cell Expressing Naive Phenotype Confers Protection against Tuberculosis Infection in the Lung.

Failure of the most recent tuberculosis (TB) vaccine trial to boost bacillus Calmette-Guérin-mediated anti-TB immunity despite the induction of Th1-specific central memory cell and effector memory cell responses highlights the importance of identifying optimal T cell targets for protective vaccines. In this study, we describe a novel, Mycobacterium tuberculosis-specific IFN-γ+CD4+ T cell population expressing surface markers characteristic of naive-like memory T cells (TNLM), which were induced in both human (CD45RA+CCR7+CD27+CD95-) and murine (CD62L+CD44-Sca-1+CD122-) systems in response to mycobacteria. In bacillus Calmette-Guérin-vaccinated subjects and those with latent TB infection, TNLM were marked by the production of IFN-γ but not TNF-α and identified by the absence of CD95 expression and increased surface expression CCR7, CD27, the activation markers T-bet, CD69, and the survival marker CD74. Increased tetramer-positive TNLM frequencies were noted in the lung and spleen of ESAT-61-20-specific TCR transgenic mice at 2 wk postinfection with M. tuberculosis and progressively decreased at later time points, a pattern not seen with TNF-α+CD4+ T cells expressing naive cell surface markers. Importantly, adoptive transfer of highly purified TNLM alone, from vaccinated ESAT-61-20-specific TCR transgenic mice, conferred equivalent protection against M. tuberculosis infection in the lungs of Rag-/- mice when compared with total memory populations (central and effector memory cells). Thus, TNLM may represent a memory T cell population that, if optimally targeted, may significantly improve future TB vaccine responses.

Respiratory Enterovirus (like Parainfluenza Virus) Can Cause Chronic Lung Disease if Protection by Airway Epithelial STAT1 Is Lost

Epithelial barrier cells are proposed to be critical for host defense, and airway epithelial cell capacity for IFN signal transduction is presumed to protect against respiratory viral infection. However, it has been difficult to fully test these concepts given the absence of tools to analyze IFN signaling specific to airway epithelial cells in vivo. To address these issues, we generated a new line of transgenic mice with Cre-driver genes (Foxj1 and Scgb1a1) for a floxed-Stat1 allele (designated Foxj1-Scgb1a1-Cre-Stat1f/f mice) to target the master IFN signal regulator STAT1 in airway epithelial cells and tested these mice for control of infection because of mouse parainfluenza (Sendai) virus and human enterovirus D68 (EV-D68). Indeed, both types of infections showed increases in viral titers and severity of acute illness in Foxj1-Scgb1a1-Cre-Stat1f/f mice and conventional Stat1-/- mice compared with wild-type mice. In concert, the chronic lung disease that develops after Sendai virus infection was also increased in Foxj1-Scgb1a1-Cre-Stat1f/f and Stat1-/ - mice, marked by airway and adjacent parenchymal immune cell infiltration and mucus production for at least 7 wk postinfection. Unexpectedly, relatively mild EV-D68 infection also progressed to chronic lung disease in Foxj1-Scgb1a1-Cre-Stat1f/f and Stat1 -/- mice but was limited (like viral replication) to airways. The results thereby provide proof-of-concept for a critical role of barrier epithelial cells in protection from acute illness and chronic disease after viral infection and suggest a specific role for airway epithelial cells given the limitation of EV-D68 replication and acute and chronic manifestations of disease primarily to airway tissue.

Treatment of Borrelia burgdorferi-Infected Mice with Apoptotic Cells Attenuates Lyme Arthritis via PPAR-γ.

Infection of mice with Borrelia burgdorferi causes an inflammatory arthritis that peaks 3-4 wk postinfection and then spontaneously resolves. Although the recruitment of neutrophils is known to drive the development of arthritis, mechanisms of disease resolution remain unclear. Efficient clearance of apoptotic cells (AC) is likely an important component of arthritis resolution. In this article, we show the number of AC increases in the joints of B. burgdorferi-infected mice around day 21 postinfection and peaks around day 28. Injection of AC directly into the ankles of B. burgdorferi-infected mice limited ankle swelling but had no effect on spirochete clearance or arthritis severity scores. In vitro, addition of AC to bone marrow macrophage cultures decreased B. burgdorferi-induced TNF-α and KC and increased IL-10. In addition, phagocytosis of B. burgdorferi and neutrophil migration to LTB4 were inhibited by AC. Exogenous AC caused an increase in peroxisome proliferator-activated receptor-γ (PPAR-γ) expression both in vitro and in vivo during B. burgdorferi infection. The PPAR-γ agonist rosiglitazone elicited similar changes in macrophage cytokine production and neutrophil migration as exogenous AC. Addition of the PPAR-γ antagonist GW 9662 abrogated the effects of AC in vitro. Injection of rosiglitazone directly into the tibiotarsal joints of B. burgdorferi-infected mice decreased ankle swelling and immune cell recruitment, similar to the injection of AC. These results suggest that clearance of AC plays a role in the resolution of inflammation during experimental Lyme arthritis through the activation of PPAR-γ. PPAR-γ agonists, such as rosiglitazone, may therefore be effective treatments for inducing arthritis resolution.

Identification of factors associated with virus level in tonsils of pigs experimentally infected with porcine reproductive and respiratory syndrome virus.

Porcine reproductive and respiratory syndrome (PRRS) is one of the most important global swine diseases from both an economic and animal welfare standpoint. PRRS has plagued the US swine industry for over 25 yr, and containment of PRRS virus (PRRSV) has been unsuccessful to date. The primary phase of PRRS, tracked by serum viremia, typically clears between 21 and 42 d postinfection (dpi) but tonsils are a main site of PRRSV persistence and PRRSV can be detected in tonsils in excess of 150 dpi. Measuring tonsil virus (TV) levels at late stages of infection (6 to 7 wk postinfection) can be used to assess tonsil persistence, as levels of virus in tonsil at this time likely influence how long the virus will remain in the tissue. TV levels were measured on pigs experimentally infected with either the NVSL-97-7895 (NVSL; n = 524) or KS-2006-72109 (KS06; n = 328) PRRSV type 2 isolates across five trials. The objectives of this study were to (i) estimate the heritability of TV levels at 35 or 42 dpi; (ii) identify factors the affect TV level, including serum viremia; (iii) identify genomic regions associated with TV level; and (iv) compare results for the two PRRSV isolates. TV level was lowly heritable for both isolates (NVSL: 0.05 ± 0.06; KS06: 0.11 ± 0.10). Level of TV was phenotypically associated with traits related to viral clearance from serum: pigs with low TV levels had an earlier and faster rate of maximal serum viral clearance, lower total serum viral load, and lower viremia level at 35 or 42 dpi. Although no genomic regions with major effects on TV level were identified, several showed some association (>0.1% of total genetic variance in the NVSL-infected dataset, the KS06-infected dataset, and the combined dataset). These regions contained the genes CCL1, CCL2, CCL8, HS3ST3B1, GALNT10, TCF7, C1QA/B/C, HPSE, G0S2, and CD34, which are involved in viral infiltration or replication, immune cell migration, and viral clearance from tissue. Results were similar between the two PRRSV isolates. In conclusion, selection for viral clearance traits in serum may reduce PRRSV persistence in the tonsil across PRRSV isolates. However, genetic correlations need to be estimated to determine whether this will be successful.

Influenza A Virus Infection Causes Chronic Lung Disease Linked to Sites of Active Viral RNA Remnants.

Clinical and experimental observations suggest that chronic lung disease is linked to respiratory viral infection. However, the long-term aspect of this relationship is not yet defined using a virus that replicates at properly high levels in humans and a corresponding animal model. In this study, we show that influenza A virus infection achieves 1 × 106-fold increases in viral load in the lung and dose-dependent severity of acute illness in mice. Moreover, these events are followed by persistence of negative- and positive-strand viral RNA remnants for 15 wk and chronic lung disease for at least 26 wk postinfection. The disease is manifested by focal areas of bronchiolization and mucus production that contain increased levels of viral RNA remnants along with mucin Muc5ac and Il13 mRNA compared with uninvolved areas of the lung. Excess mucus production and associated airway hyperreactivity (but not fibrosis or emphysema) are partially attenuated with loss of IL-13 production or signaling (using mice with IL-13 or STAT6 deficiency). These deficiencies cause reciprocal increases in l17a mRNA and neutrophils in the lung; however, none of these disease endpoints are changed with IL-13/IL-17a compared with IL-13 deficiency or STAT6/IL-17a compared with STAT6 deficiency. The results establish the capacity of a potent human respiratory virus to produce chronic lung disease focally at sites of active viral RNA remnants, likely reflecting locations of viral replication that reprogram the region. Viral dose dependency of disease also implicates high-level viral replication and severity of acute infection as determinants of chronic lung diseases such as asthma and COPD with IL-13-dependent and IL-13/IL-17-independent mechanisms.

Pathogenesis of duck circovirus genotype 1 in experimentally infected Pekin ducks.

Ducks infected with duck circovirus (DuCV) exhibit feathering disorder, growth retardation, and low body weight. The virus can induce immunosuppression and increase rates of infection caused by other pathogens. The purpose of the present study was to investigate the pathogenesis of DuCV in experimentally infected Pekin ducks. At postmortem examination, gross lesions were observed in the immune organs including bursa of Fabricius (BF), thymus, and spleen. Hemorrhage, lymphocytic depletion, necrosis, and degeneration were observed in the bursal tissues by histological examination. The TUNEL assay was performed with bursal tissue. There was a significant difference of the apoptosis rate between the negative and DuCV-infected ducks. The earliest time point for detection of DuCV DNA in sera, cloacal swabs, and organs was 1 wk post-infection (WPI). Viral shedding was persistent and detectable at the end of the experiment (10 WPI). The findings provide evidence that horizontal transmission and persistent infection are the characteristics of DuCV. The organ with the highest mean viral load was the spleen, followed by BF, cecal tonsil, lung, thymus, liver, and kidney. We successfully established an experimental DuCV genotype 1 (DuCV-1) infection in Pekin ducks and demonstrated the pathogenicity and persistence of DuCV-1. In conclusion, DuCV-1 caused extensive damage to the immune organs that may have resulted in immunosuppression. Pathobiological characteristics of DuCV-1 include systemic infection, persistent infection, and horizontal transmission. These features allow DuCV-1 to circulate more easily in farms and increase the susceptibility of ducks to other diseases.

Giardia Infection of the Small Intestine Induces Chronic Colitis in Genetically Susceptible Hosts.

The lumen-dwelling protozoan Giardia is an important parasitic cause of diarrheal disease worldwide. Infection can persist over extended periods with minimal intestinal inflammation, suggesting that Giardia may attenuate host responses to ensure its survival, although clearance eventually occurs in most cases. IL-10 is an anti-inflammatory regulator critical for intestinal homeostasis and controlling host responses to bacterial exposure, yet its potential role in coordinating antiprotozoal host defense in the intestine is not known. In this study, we found that murine infection with the natural enteric pathogen Giardia muris induced a transient IL-10 response after 2-4 wk at the primary site of infection in the upper small intestine, but parasite colonization and eradication were not affected by the absence of the cytokine in gene-targeted mice. However, IL-10 was critical for controlling infection-associated immunological sequelae in the colon because severe and persistent diarrhea and colitis were observed in IL-10-deficient mice within 1-2 wk postinfection but not in uninfected littermate controls. Inflammation was characterized by epithelial hyperplasia, neutrophil and macrophage expansion, and Th1 induction and could be prevented by blockade of IL-12/IL-23 p40 but not depletion of CD11c+ dendritic cells. Furthermore, the intestinal microbiota underwent characteristic shifts in composition and was required for disease because antibiotics and loss of TLR signaling in MyD88-deficient mice protected against colitis. Together, our data suggest that transient infection by a luminal and seemingly noninflammatory pathogen can trigger sustained colitis in genetically susceptible hosts, which has broader implications for understanding postinfectious syndromes and other chronic intestinal inflammatory conditions.

Effect of an artificial Ascaridia galli infection on egg production, immune response, and liver lipid reserve of free-range laying hens

This study was conducted to determine the effect of Ascaridia galli infection on free-range laying hens. Lohmann Brown laying hens (n = 200) at 17 wk of age were allocated to 4 treatment groups (n = 50 per group), each with 5 replicate pens of 10 hens. Hens in 3 treatment groups were orally inoculated with different doses of embryonated A. galli eggs: low (250 eggs), medium (1,000 eggs), and high (2,500 eggs) levels, whereas hens of the control group were not infected. Infection levels were monitored using excreta egg counts and mature A. galli worm counts in the intestine. Anti A. galli antibody titers (IgY) in the serum were measured prior to infection, and at 6, 11, 15, and 20 wk post infection (PI) and in egg yolk at 11 and 20 wk PI. Parameters evaluated included feed intake, egg production, egg weight, egg mass, FCR, liver weight, liver fat, and intra epithelial immune cell infiltration. The results showed no difference in feed intake, body weight, or FCR among any treatment groups (P > 0.05). Egg production was lower in the low infection group compared to other groups at 20 wk of age (P < 0.01). Serum IgY was higher in the infected groups’ hens at 20 wk PI compared to control group hens (P < 0.01). Yolk IgY increased significantly over time and was higher in infected hens compared to hens of the control group at 11 and 20 wk PI (P < 0.001). No differences were observed in liver lipid content or intraepithelial lymphocytes infiltration among treatment groups. Ascaridia galli eggs in the coprodeum content and adult A. galli worm count were higher in infected hens compared to hens of the control group (P < 0.01). In conclusion, the effects of artificial infection with A. galli on the parameters investigated were minor, and egg yolk antibody may be a more reliable indicator of A. galli infection than serum antibody or excreta egg count.

Differential Dynamics of HIV Infection in Humanized MISTRG versus MITRG Mice

Abstract Humanized mice are a powerful tool to study HIV in vivo. The recently generated mouse strains MITRG and MISTRG, which differ in human SIRPα expression, support an improved human myeloid lineage development from human hematopoietic stem and progenitor cells. The rationale of the study was the characterization of the two mouse strains during an HIV infection with CCR5- and CXCR4-tropic viruses. Upon HIV infection, we observed HIV dissemination and sustained viral load over 20 wk in peripheral blood in both reconstituted mouse strains. However, HIV RNA levels were significantly lower in MITRG mice compared with MISTRG mice during the first 8 wk postinfection. HIV-infected MISTRG mice showed lymphocyte activation and changes in lymphocyte subsets in blood and spleen, recapitulating hallmarks of HIV infection in humans. Depletion of murine tissue-resident macrophages in MITRG mice led to significantly elevated viral loads, and lymphocyte levels were similar to those in HIV-infected MISTRG mice. Depletion of CD8+ T cells in MISTRG mice before HIV infection resulted in substantially decreased CD4+ T cell levels, indicating functionality of human CD8+ T cells; depletion of CD4+CD8+ thymocytes may have contributed, in part, to the latter finding. In summary, MITRG and MISTRG mice represent novel HIV mouse models, despite differential HIV dynamics.

Modulation of Roquin Function in Myeloid Cells Reduces Mycobacterium tuberculosis-Induced Inflammation.

Damaging inflammation is a hallmark of Mycobacterium tuberculosis infection, and understanding how this is regulated is important for the development of new therapies to limit excessive inflammation. The E3 ubiquitin ligase, Roquin, is involved in immune regulation; however, its role in immunity to M. tuberculosis is unknown. To address this, we infected mice with a point mutation in Roquin1/Rc3h1 (sanroque). Aerosol-infected sanroque mice showed enhanced control of M. tuberculosis infection associated with delayed bacterial dissemination and upregulated TNF production in the lungs after 2 wk. However, this early control of infection was not maintained, and by 8 wk postinfection sanroque mice demonstrated an increased bacterial burden and dysregulated inflammation in the lungs. As the inflammation in the lungs of the sanroque mice could have been influenced by emerging autoimmune conditions that are characteristic of the mice aging, the function of Roquin was examined in immune cell subsets in the absence of autoimmune complications. M. bovis bacillus Calmette-Guérin-primed sanroque T cells transferred into Rag1-/- mice provided equivalent protection in the spleen and liver. Interestingly, the transfer of mycobacteria-specific (P25 CD4+ TCR transgenic) wild-type spleen cells into sanroqueRag1-/- mice actually led to enhanced protection with reduced bacterial load, decreased chemokine expression, and reduced inflammation in the lungs compared with transfers into Rag1-/- mice expressing intact Roquin. These studies suggest that modulation of Roquin in myeloid cells may reduce both inflammation and bacterial growth during the chronic phase of M. tuberculosis infection.

Pig model mimicking chronic hepatitis E virus infection in immunocompromised patients to assess immune correlates during chronicity

Chronic hepatitis E virus (HEV) infection is a significant clinical problem in immunocompromised individuals such as organ transplant recipients, although the mechanism remains unknown because of the lack of an animal model. We successfully developed a pig model of chronic HEV infection and examined immune correlates leading to chronicity. The conditions of immunocompromised patients were mimicked by treating pigs with an immunosuppressive regimen including cyclosporine, azathioprine, and prednisolone. Immunocompromised pigs infected with HEV progressed to chronicity, because 8/10 drug-treated HEV-infected pigs continued fecal virus shedding beyond the acute phase of infection, whereas the majority (7/10) of mock-treated HEV-infected pigs cleared fecal viral shedding at 8 wk postinfection. During chronic infection, serum levels of the liver enzyme γ-glutamyl transferase and fecal virus shedding were significantly higher in immunocompromised HEV-infected pigs. To identify potential immune correlates of chronic infection, we determined serum levels of cytokines and cell-mediated immune responses in pigs. Results showed that HEV infection of immunocompromised pigs reduced the serum levels of Th1 cytokines IL-2 and IL-12, and Th2 cytokines IL-4 and IL-10, particularly during the acute phase of infection. Furthermore IFN-γ-specific CD4+ T-cell responses were reduced in immunocompromised pigs during the acute phase of infection, but TNF-α-specific CD8+ T-cell responses increased during the chronic phase of infection. Thus, active suppression of cell-mediated immune responses under immunocompromised conditions may facilitate the establishment of chronic HEV infection. This pig model will aid in delineating the mechanisms of chronic HEV infection and in developing effective therapeutics against chronic hepatitis E.

Schistosoma japonicum attenuates dextran sodium sulfate-induced colitis in mice via reduction of endoplasmic reticulum stress.

AIMTo elucidate the impact of Schistosoma (S.) japonicum infection on inflammatory bowel disease by studying the effects of exposure to S. japonicum cercariae on dextran sodium sulfate (DSS)-induced colitis.METHODSInfection was percutaneously established with 20 ± 2 cercariae of S. japonicum, and colitis was induced by administration of 3% DSS at 4 wk post infection. Weight change, colon length, histological score (HS) and disease activity index (DAI) were evaluated. Inflammatory cytokines, such as IL-2, IL-10 and IFN-γ, were tested by a cytometric bead array and real-time quantitative polymerase chain reaction (RT-PCR). Protein and mRNA levels of IRE1α, IRE1β, GRP78, CHOP, P65, P-P65, P-IκBα and IκBα in colon tissues were examined by Western blot and RT-PCR, respectively. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling positive cells, cleaved-caspase 3 expression and Bcl2/Bax were investigated to assess the apoptosis in colon tissues.RESULTSMice infected with S. japonicum cercariae were less susceptible to DSS. Mice infected with S. japonicum cercariae and treated with DSS showed decreased weight loss, longer colon, and lower HS and DAI compared with mice treated with DSS alone. A substantial decrease in Th1/Th2/Th17 response was observed after infection with S. japonicum. Endoplasmic reticulum (ER) stress and the nuclear factor-kappa B (NF-κB) pathway were reduced in mice infected with S. japonicum cercariae and treated with DSS, along with ameliorated celluar apoptosis, in contrast to mice treated with DSS alone.CONCLUSIONExposure to S. japonicum attenuated inflammatory response in a DSS-induced colitis model. In addition to the Th1/Th2/Th17 pathway and NF-κB pathway, ER stress was shown to be involved in mitigating inflammation and decreasing apoptosis. Thus, ER stress is a new aspect in elucidating the relationship between helminth infection and inflammatory bowel disease (IBD), which may offer new therapeutic methods for IBD.