Sir Peter Lachmann-Outstanding and Inspirational Immunologist.

Sir Peter Lachmann was an exceptional and gifted scientist whose intellectual contributions to biomedical science have been immense.[...].

Uganda's "EID Systems Strengthening" model produces significant gains in testing, linkage, and retention of HIV-exposed and infected infants: An impact evaluation.

INTRODUCTION: A review of Uganda's HIV Early Infant Diagnosis (EID) program in 2010 revealed poor retention outcomes for HIV-exposed infants (HEI) after testing. The review informed development of the 'EID Systems Strengthening' model: a set of integrated initiatives at health facilities to improve testing, retention, and clinical care of HIV-exposed and infected infants. The program model was piloted at several facilities and later scaled countrywide. This mixed-methods study evaluates the program's impact and assesses its implementation. METHODS: We conducted a retrospective cohort study at 12 health facilities in Uganda, comprising all HEI tested by DNA PCR from June 2011 to May 2014 (n = 707). Cohort data were collected manually at the health facilities and analyzed. To assess impact, retention outcomes were statistically compared to the baseline study's cohort outcomes. We conducted a cross-sectional qualitative assessment of program implementation through 1) structured clinic observation and 2) key informant interviews with health workers, district officials, NGO technical managers, and EID trainers (n = 51). RESULTS: The evaluation cohort comprised 707 HEI (67 HIV+). The baseline study cohort contained 1268 HEI (244 HIV+). Among infants testing HIV+, retention in care at an ART clinic increased from 23% (57/244) to 66% (44/67) (p < .0001). Initiation of HIV+ infants on ART increased from 36% (27/75) to 92% (46/50) (p < .0001). HEI receiving 1st PCR results increased from 57% (718/1268) to 73% (518/707) (p < .0001). Among breastfeeding HEI with negative 1st PCR, 55% (192/352) received a confirmatory PCR test, a substantial increase from baseline period. Testing coverage improved significantly: HIV+ pregnant women who brought their infants for testing after birth increased from 18% (67/367) to 52% (175/334) (p < .0001). HEI were tested younger: mean age at DBS test decreased from 6.96 to 4.21 months (p < .0001). Clinical care for HEI was provided more consistently. Implementation fidelity was strong for most program components. The strongest contributory interventions were establishment of 'EID Care Points', integration of clinical care, longitudinal patient tracking, and regular health worker mentorship. Gaps included limited follow up of lost infants, inconsistent buy-in/ownership of health facility management, and challenges sustaining health worker motivation. DISCUSSION: Uganda's 'EID Systems Strengthening' model has produced significant gains in testing and retention of HEI and HIV+ infants, yet the country still faces major challenges. The 3 core concepts of Uganda's model are applicable to any country: establish a central service point for HEI, equip it to provide high-quality care and tracking, and develop systems to link HEI to the service point. Uganda's experience has shown the importance of intensively targeting systemic bottlenecks to HEI retention at facility level, a necessary complement to deploying rapidly scalable technologies and other higher-level initiatives.

Native Joint Septic Arthritis: Comparison of Outcomes with Medical and Surgical Management.

OBJECTIVE: To determine whether there are differences in the outcomes of native joint septic arthritis (SA) in adults, based on medical versus surgical management. METHODS: A 10-year retrospective single-center study was conducted of patients admitted to a tertiary care hospital between January 1, 2006 and December 31, 2015 with a diagnosis of SA to compare outcomes based on the management approach taken: medical (bedside closed-needle joint aspiration) versus surgical (arthrotomy/arthroscopy). Evaluated outcomes included joint recovery, time to recovery, length of stay, disposition to home versus rehabilitation unit, recurrence of SA in the same joint, and mortality. RESULTS: Of 118 confirmed cases of SA, 48 were in prosthetic joints and 70 were in native joints, and 61 met our inclusion criteria. Forty-one (67%) patients received surgery, and 20 (33%) received closed-needle aspiration. There was no statistically significant difference in long-term outcomes between the two groups at 12 months. Patients managed medically were more likely to experience full recovery at 3 months and were less likely to need short-term rehabilitation. CONCLUSIONS: Medical management with closed-needle aspiration may be an adequate approach to the treatment of native joint infections.

Retention outcomes and drivers of loss among HIV-exposed and infected infants in Uganda: a retrospective cohort study.

BACKGROUND: Uganda's HIV Early Infant Diagnosis (EID) program rapidly scaled up testing of HIV-exposed infants (HEI) in its early years. However, little was known about retention outcomes of HEI after testing. Provision of transport refunds to HEI caregivers was piloted at 3 hospitals to improve retention. This study was conducted to quantify retention outcomes of tested HEI, identify factors driving loss-to-follow-up, and assess the effect of transport refunds on HEI retention. METHODS: This mixed-methods study included 7 health facilities- retrospective cohort review at 3 hospitals and qualitative assessment at all facilities. The cohort comprised all HEI tested from September-2007 to February-2009. Retention data was collected manually at each hospital. Qualitative methods included health worker interviews and structured clinic observation. Qualitative data was synthesized, analyzed and triangulated to identify factors driving HEI loss-to-follow-up. RESULTS: The cohort included 1268 HEI, with 244 testing HIV-positive. Only 57% (718/1268) of tested HEI received results. The transport refund pilot increased the percent of HEI caregivers receiving test results from 54% (n = 763) to 58% (n = 505) (p = .08). HEI were tested at late ages (Mean = 7.0 months, n = 1268). Many HEI weren't tested at all: at 1 hospital, only 18% (67/367) of HIV+ pregnant women brought their HEI for testing after birth. Among HIV+ infants, only 40% (98/244) received results and enrolled at an ART Clinic. Of enrolled HIV+ infants, only 43% (57/98) were still active in chronic care. 36% (27/75) of eligible HIV+ infants started ART. Our analysis identified 6 categories of factors driving HEI loss-to-follow-up: fragmentation of EID services across several clinics, with most poorly equipped for HEI care/follow-up; poor referral mechanisms and data management systems; inconsistent clinical care; substandard counseling; poor health worker knowledge of EID; long sample-result turnaround times. DISCUSSION: The poor outcomes for HEI and HIV+ infants have highlighted an urgent need to improve retention and linkage to care. To address the identified gaps, Uganda's Ministry of Health and the Clinton Health Access Initiative developed a new implementation model, shifting EID from a lab-based diagnostic service to an integrated clinic-based chronic care model. This model was piloted at 21 facilities. An evaluation is needed.

Extracellular Tau Oligomers Induce Invasion of Endogenous Tau into the Somatodendritic Compartment and Axonal Transport Dysfunction.

Aggregates composed of the microtubule associated protein, tau, are a hallmark of Alzheimer's disease and non-Alzheimer's tauopathies. Extracellular tau can induce the accumulation and aggregation of intracellular tau, and tau pathology can be transmitted along neural networks over time. There are six splice variants of central nervous system tau, and various oligomeric and fibrillar forms are associated with neurodegeneration in vivo. The particular extracellular forms of tau capable of transferring tau pathology from neuron to neuron remain ill defined, however, as do the consequences of intracellular tau aggregation on neuronal physiology. The present study was undertaken to compare the effects of extracellular tau monomers, oligomers, and filaments comprising various tau isoforms on the behavior of cultured neurons. We found that 2N4R or 2N3R tau oligomers provoked aggregation of endogenous intracellular tau much more effectively than monomers or fibrils, or of oligomers made from other tau isoforms, and that a mixture of all six isoforms most potently provoked intracellular tau accumulation. These effects were associated with invasion of tau into the somatodendritic compartment. Finally, we observed that 2N4R oligomers perturbed fast axonal transport of membranous organelles along microtubules. Intracellular tau accumulation was often accompanied by increases in the run length, run time and instantaneous velocity of membranous cargo. This work indicates that extracellular tau oligomers can disrupt normal neuronal homeostasis by triggering axonal tau accumulation and loss of the polarized distribution of tau, and by impairing fast axonal transport.

Consolidating HIV testing in a public health laboratory for efficient and sustainable early infant diagnosis (EID) in Uganda.

Uganda introduced an HIV Early Infant Diagnosis (EID) program in 2006, and then worked to improve the laboratory, transportation, and clinical elements. Reported here are the activities involved in setting up a prospective analysis in which the Ministry of Health, with its NGO partners, determined it would be more effective and efficient to consolidate the initial eight-laboratory system for EID testing of HIV dried blood samples offered by two nongovernmental partners operating research facilities into a single well-equipped and staffed laboratory within the Ministry. A retrospective analysis confirmed that redesign reduced overhead cost per PCR test of HIV dried blood samples from US$22.20 to an average of $5. Along with the revamped system of sample collection, transportation, and result communication, Uganda has been able to vastly increase the HIV diagnosis of babies and engagement of them and their mothers in clinical care, including antiretroviral therapy. Uganda reduced turnaround times for results reporting to clinicians from more than a month in 2006 to just 2 weeks by 2014, even as samples tested increased dramatically. The next challenge is overcoming loss of babies and mothers to follow up.

Uganda's new national laboratory sample transport system: a successful model for improving access to diagnostic services for Early Infant HIV Diagnosis and other programs.

INTRODUCTION: Uganda scaled-up Early HIV Infant Diagnosis (EID) when simplified methods for testing of infants using dried blood spots (DBS) were adopted in 2006 and sample transport and management was therefore made feasible in rural settings. Before this time only 35% of the facilities that were providing EID services were reached through the national postal courier system, Posta Uganda. The transportation of samples during this scale-up, therefore, quickly became a challenge and varied from facility to facility as different methods were used to transport the samples. This study evaluates a novel specimen transport network system for EID testing. METHODS: A retrospective study was done in mid-2012 on 19 pilot hubs serving 616 health facilities in Uganda. The effect on sample-result turnaround time (TAT) and the cost of DBS sample transport on 876 sample-results was analyzed. RESULTS: The HUB network system provided increased access to EID services ranging from 36% to 51%, drastically reduced transportation costs by 62%, reduced turn-around times by 46.9% and by a further 46.2% through introduction of SMS printers. CONCLUSIONS: The HUB model provides a functional, reliable and efficient national referral network against which other health system strengthening initiatives can be built to increase access to critical diagnostic and treatment monitoring services, improve the quality of laboratory and diagnostic services, with reduced turn-around times and improved quality of prevention and treatment programs thereby reducing long-term costs.

Mapping and characterization of visna/maedi virus cytotoxic T-lymphocyte epitopes.

CD8(+) cytotoxic T-lymphocyte (CTL) responses have been shown to be important in the control of human and simian immunodeficiency virus infections. Infection of sheep with visna/maedi virus (VISNA), a related lentivirus, induces specific CD8(+) CTL in vivo, but the specific viral proteins recognized are not known. To determine which VISNA antigens were recognized by sheep CTL, we used recombinant vaccinia viruses expressing the different genes of VISNA: in six sheep (Finnish LandracexDorset crosses, Friesland and Lleyn breeds) all VISNA proteins were recognized except TAT. Two sheep, shown to share major histocompatibility complex (MHC) class I alleles, recognized POL and were used to map the epitope. The pol gene is 3267 bp long encoding 1088 aa. By using recombinant vaccinia viruses a central portion (nt 1609-2176, aa 537-725) was found to contain the CTL epitope and this was mapped with synthetic peptides to a 25 aa region (aa 612-636). When smaller peptides were used, a cluster of epitopes was detected: at least three epitopes were present, at positions 612-623: DSRYAFEFMIRN; 620-631: MIRNWDEEVIKN; and 625-635: EEVIKNPIQAR. A DNA-prime-modified vaccinia virus Ankara (MVA)-boost strategy was employed to immunize four sheep shown to share MHC class I allele(s) with the sheep above. Specific CTL activity developed in all the immunized sheep within 3 weeks of the final MVA boost although half the sheep showed evidence of specific reactivity after the DNA-prime immunizations. This is the first report, to our knowledge, of induction of CTL by a DNA-prime-boost method in VISNA infection.

Cloning and characterization of ovine beta2-microglobulin cDNAs.

Beta-2-microglobulin (beta(2)m) is the light chain of the major histocompatibility complex (MHC) class I cell surface heterodimer. beta(2)m is well conserved across most species with few polymorphisms seen within species. The aims of this study were to clone and express ovine beta(2)m and investigate if allelic variation of ovine beta(2)m exists. Ovine beta(2)m clones were isolated from five sheep of three breeds by reverse-transcription polymerase chain reaction (RT-PCR). Sequence analysis showed that four ovine beta(2)m sequences were obtained. Within breeds and individual animals there was evidence of allelic variation of ovine beta(2)m. An expression system was established to express one of the alleles with an ovine MHC class I cDNA clone in human embryo kidney cells (HEK293) and quail cells (QT35). Transfection experiments showed that ovine beta(2)m was expressed and directed the expression of ovine MHC class I heavy chain to the cell surface of the transfected cells. Both bovine and human beta(2)m supported ovine MHC class I heavy chain cell surface expression.

Salmonella infection of afferent lymph dendritic cells.

The interactions of Salmonella enterica subspecies I serotype Abortusovis (S. Abortusovis) with ovine afferent lymph dendritic cells (ALDCs) were investigated for their ability to deliver Maedi visna virus (MVV) GAG p25 antigens to ALDCs purified from afferent lymph. Salmonellae were found to enter ALDC populations by a process of cell invasion, as confirmed by electron and confocal microscopy. This led to phenotypical changes in ALDC populations, as defined by CD1b and CD14 expression. No differences in the clearance kinetics of intracellular aroA-negative Salmonella from CD1b+ CD14lo and CD1b+ CD14(-) ALDC populations were noted over 72 h. ALDCs were also shown to present MVV GAG p25 expressed by aroA-negative S. Abortusovis to CD4+ T lymphocytes. Thus, the poor immune responses that Salmonella vaccines elicited in large animal models compared with mice are neither a result of an inability of Salmonella to infect large animal DCs nor an inability of these DCs to present delivered antigens. However, the low efficiency of infection of ALDC compared with macrophages or monocyte-derived DCs may account for the poor immune responses induced in large animal models.

Unique features and distribution of the chicken CD83+ cell.

The central importance of dendritic cells (DC) in both innate and acquired immunity is well recognized in the mammalian immune system. By contrast DC have yet to be characterized in avian species despite the fact that avian species such as the chicken have a well-developed immune system. CD83 has proven to be an excellent marker for DC in human and murine immune systems. In this study we identify chicken CD83 (chCD83) as the avian equivalent of the human and murine DC marker CD83. We demonstrate for the first time that unlike human and murine CD83, chCD83 is uniquely expressed in the B cell areas of secondary lymphoid organs and in organs with no human or murine equivalent such as the bursa and Harderian gland. Furthermore through multicolor immunofluorescence, we identify chCD83(+) populations that have unique attributes akin to both DC and follicular DC. These attributes include colocalization with B cell microenvironments, MHC class II expression, dendritic morphology, and distribution throughout peripheral and lymphoid tissues.

Direct detection of disease associated prions in brain and lymphoid tissue using antibodies recognizing the extreme N terminus of PrPC.

A simple diagnostic test is described for the detection of TSE in bovine, ovine and human brain and lymphoid tissue that obviates the use of proteinase K as a discriminating reagent. The immunoassay utilises high affinity anti-peptide antibodies that appear blind to the normal isoform of prion protein (PrP(C)). These reagents have been produced with novel N-terminal chimeric peptides and we hypothesise that the retention and stability of the extreme N-terminus of PrP in the disease-associated aggregate makes it an operationally specific marker for TSE. Accordingly, the assay involves homogenisation of the tissue directly in 8M guanidine hydrochloride, a simple one-step capture of PrP(Sc) followed by detection with a europium-labelled anti-PrP(C) antibody. This rapid assay clearly differentiates between levels of disease-associated PrP extracted from brain and lymphoid tissues taken from confirmed TSE positive and negative cattle and sheep. The assay can also be used to detect PrP(Sc) in cases of vCJD.

Serum containing ovine IgG2 antibody specific for maedi visna virus envelope glycoprotein mediates antibody dependent cellular cytotoxicity.

Antibody-dependent cell-mediated cytotoxicity (ADCC) specific for maedi visna virus (MVV) has never been described. The IgG antibody response to MVV is restricted to an IgG1 response whilst MVV specific IgG2 is never seen in persistently infected sheep. To determine whether the isotypic restriction of the antibody response is responsible for the lack of ADCC, an ADCC assay was developed using polyclonal serum raised to recombinant MVV ENV protein. Sheep immunised with a recombinant GST:SUenv fusion protein in complete Freund's adjuvant produced an antibody response which contained IgG1 and IgG2 antibodies. The activity of this serum in an ADCC assay was compared to serum from persistently infected sheep. Serum from immunised sheep mediated ADCC reactions whilst no activity was ever seen in persistently infected sheep serum. IgG2 may therefore be the possible effector isotype for ADCC reactions against MVV. Failure of the IgG2 dependent ADCC system in vivo may contribute to the persistence of MVV-infected macrophages in vivo.

Quantitation of ovine cytokine mRNA by real-time RT-PCR.

In this study we describe for the first time the dynamics of the expression of the cytokines, IL-1beta, IL-12p40, TNFalpha in ovine dendritic cells and macrophages after LPS stimulation. Real time RT-PCR was used for the quantitation of these cytokines and IL-4 and IFNgamma as well as two potential housekeeping genes (HKG), ATPase and GAPDH, in mRNAs from ovine leucocyte populations. Both dual-labelled probes (TAMRA/FAM) and SYBR Green assays were utilised, using a Corbett Research RotorGene and ABI 7700 machine. In order to quantitate each cytokine in our assays all C(T) values were compared to a standard curve generated using plasmid DNA containing the cytokine of interest. To validate our assays, concanavalin A-stimulated peripheral blood mononuclear cells (PBMCs) and LPS-stimulated monocyte-derived dendritic cells (MoDC) and monocyte-derived macrophages (MDMØ) were examined. We found that peak cytokine mRNA expression was between 3 and 6 h for the cytokines examined except for IL-12p40 where peak cytokine release was around 12 h post-stimulation in MDMØ and PBMCs. However, in MoDCs, peak IL-12p40 mRNA expression was observed within 3-6 h. We have identified a sensitive and reliable method for the identification of ovine cytokine mRNAs.

An immunoassay for the pathological form of the prion protein based on denaturation and time resolved fluorometry.

Concern about the possible secondary spread of variant Creutzfeldt-Jakob disease (vCJD) through blood transfusion and blood products has increased the need for a sensitive and rapid test for the identification of PrP(Sc) in specimens collected non-invasively from living persons. Furthermore, an accurate estimate of the prevalence of pre-clinical vCJD in the British population would be possible if there were such a test that could be applied to specimens available readily (e.g. blood and urine). As a first step towards that goal, we have developed a simple and sensitive test for the detection of PrP(Sc) in peripheral tissues and brain of vCJD patients, based on the differential extraction of PrP(Sc) with guanidine hydrochloride. The prion protein (PrP) isoforms are extracted sequentially from homogenized tissue by applying two different concentrations of this chaotropic agent. Each extraction yields a fraction of the PrP isoforms with different solubilities in guanidine hydrochloride. Quantitation of the two fractions (relatively insoluble or relatively soluble) using time resolved fluorescence (DELFIA) as a reporter system allows differentiation between PrP(Sc) infected and non-infected tissues. The assay has a detection limit of 10 pg PrP, is robust and could be automated.

Immune response to individual maedi-visna virus gag antigens.

The lesions caused by maedi-visna virus (MVV) are known to be immune mediated with a presumed contribution by the response to viral antigens. However, very little is known about the T-cell response to individual viral proteins. We have therefore expressed the three individual gag antigens of MVV strain EV1 (p16, p25, and p14) in a bacterial expression system and used the purified recombinant proteins to analyze the antibody and CD4+ T-cell response to MVV. Plasma samples were taken from sheep after 1 year of infection with MVV. The titers for antibodies in these samples were determined by indirect enzyme-linked immunosorbent assays and were as follows: anti-p25 antibody, 1:400 to >1:3,200; anti-p16 antibody, 1:400 to 1:3,200; and anti-p14 antibody, 1:<100 to 1:3,200. When the induction of antibodies was followed over time postinfection (p.i.), samples positive for anti-p25 were seen by day 24 p.i., followed by anti-p16 by day 45 p.i., and lastly anti-p14 by day 100 p.i. T-cell proliferative responses to all three gag antigens were detected in persistently infected sheep peripheral blood lymphocytes. The antigens were therefore used to raise T-cell lines from persistently infected sheep. These T-cell lines were shown to be specific for the recombinant gag antigens and for viral antigen expressed on infected macrophages. The proliferative response was restricted to major histocompatibility complex class II HLA-DR and so was due to CD4+ T lymphocytes. All three gag antigens may therefore play a role in immune-mediated lesion formation in MVV disease by presentation on infected macrophages in lesions.

An aggregation-specific enzyme-linked immunosorbent assay: detection of conformational differences between recombinant PrP protein dimers and PrP(Sc) aggregates.

The conversion of the normal cellular prion protein, PrP(C), into the protease-resistant, scrapie PrP(Sc) aggregate is the cause of prion diseases. We developed a novel enzyme-linked immunosorbent assay (ELISA) that is specific for PrP aggregate by screening 30 anti-PrP monoclonal antibodies (MAbs) for their ability to react with recombinant mouse, ovine, bovine, or human PrP dimers. One MAb that reacts with all four recombinant PrP dimers also reacts with PrP(Sc) aggregates in ME7-, 139A-, or 22L-infected mouse brains. The PrP(Sc) aggregate is proteinase K resistant, has a mass of 2,000 kDa or more, and is present at a time when no protease-resistant PrP is detectable. This simple and sensitive assay provides the basis for the development of a diagnostic test for prion diseases in other species. Finally, the principle of the aggregate-specific ELISA we have developed may be applicable to other diseases caused by abnormal protein aggregation, such as Alzheimer's disease or Parkinson's disease.

Cytokine and chemokine responses associated with clearance of a primary Salmonella enterica serovar Typhimurium infection in the chicken and in protective immunity to rechallenge.

Infection of poultry with Salmonella enterica serovar Typhimurium poses a significant risk to public health through contamination of meat from infected animals. Vaccination has been proposed to control infections in chickens. However, the vaccines are currently largely empirical, and our understanding of the mechanisms that underpin immune clearance and protection in avian salmonellosis is not complete. In this study we describe the cytokine, chemokine, and antibody responses and cellular changes in primary and secondary infections of chickens with Salmonella serovar Typhimurium. Infection of 1-week-old chickens induced early expression of a macrophage inflammatory protein (MIP) family chemokine in the spleen and liver, followed by increased expression of gamma interferon accompanied by increased numbers of both CD4(+) and CD8(+) T cells and the formation of granuloma-like follicular lesions. This response correlated with a Th1-mediated clearance of the systemic infection. Primary infection also induced specific immunoglobulin M (IgM), IgG, and IgA antibody responses. In contrast to previously published studies performed with newly hatched chicks, the expression levels of proinflammatory cytokines in the gastrointestinal tract were not greatly increased following infection. However, significant expression of the anti-inflammatory cytokine transforming growth factor beta4 was detected in the gut early in infection. Following secondary challenge, the birds were fully protected against systemic infection and showed a high level of protection against gastrointestinal colonization. Rapid expression of the MIP family chemokine and interleukin-6 was detected in the guts of these birds and was accompanied by an influx of lymphocytes. Increased levels of serum IgA-specific antibodies were also found following rechallenge. These findings suggest that cellular responses, particularly Th1 responses, play a crucial role in immune clearance in avian salmonellosis and that protection against rechallenge involves the rapid recruitment of cells to the gastrointestinal tract. Additionally, the high levels of inflammatory response found following Salmonella serovar Typhimurium infection of newly hatched chicks were not observed following infection of older birds (1 week old), in which the expression of regulatory cytokines appeared to limit inflammation.

Identification and functional characterization of chicken toll-like receptor 5 reveals a fundamental role in the biology of infection with Salmonella enterica serovar typhimurium.

Toll-like receptors (TLRs) are a major component of the pattern recognition receptor repertoire that detect invading microorganisms and direct the vertebrate immune system to eliminate infection. In chickens, the differential biology of Salmonella serovars (systemic versus gut-restricted localization) correlates with the presence or absence of flagella, a known TLR5 agonist. Chicken TLR5 (chTLR5) exhibits conserved sequence and structural similarity with mammalian TLR5 and is expressed in tissues and cell populations of immunological and stromal origin. Exposure of chTLR5+ cells to flagellin induced elevated levels of chicken interleukin-1beta (chIL-1beta) but little upregulation of chIL-6 mRNA. Consistent with the flagellin-TLR5 hypothesis, an aflagellar Salmonella enterica serovar Typhimurium fliM mutant exhibited an enhanced ability to establish systemic infection. During the early stages of infection, the fliM mutant induced less IL-1beta mRNA and polymorphonuclear cell infiltration of the gut. Collectively, the data represent the identification and functional characterization of a nonmammalian TLR5 and indicate a role in restricting the entry of flagellated Salmonella into systemic sites of the chicken.

Rapid expression of chemokines and proinflammatory cytokines in newly hatched chickens infected with Salmonella enterica serovar typhimurium.

Poultry meat and eggs contaminated with Salmonella enterica serovar Enteritidis or Salmonella enterica serovar Typhimurium are common sources of acute gastroenteritis in humans. However, the exact nature of the immune mechanisms protective against Salmonella infection in chickens has not been characterized at the molecular level. In the present study, bacterial colonization, development of pathological lesions, and proinflammatory cytokine and chemokine gene expression were investigated in the liver, spleen, jejunum, ileum, and cecal tonsils in newly hatched chickens 6, 12, 24, and 48 h after oral infection with Salmonella serovar Typhimurium. Very high bacterial counts were found in the ileum and cecal contents throughout the experiment, whereas Salmonella started to appear in the liver only from 24 h postinfection. Large numbers of heterophils, equivalent to neutrophils in mammals, and inflammatory edema could be seen in the lamina propria of the intestinal villi and in the liver. Interleukin 8 (IL-8), K60 (a CXC chemokine), macrophage inflammatory protein 1 beta, and IL-1 beta levels were significantly upregulated in the intestinal tissues and in the livers of the infected birds. However, the spleens of the infected birds show little or no change in the expression levels of these cytokines and chemokines. Increased expression of the proinflammatory cytokines and chemokines (up to several hundred-fold) correlated with the presence of inflammatory signs in those tissues. This is the first description of in vivo expression of chemokines and proinflammatory cytokines in response to oral infection with Salmonella in newly hatched chickens.