Detection of bacterial endotoxin in human tissues

Detection of bacterial lipopolysaccharide (LPS) in the absence of overt infection is a challenging problem in tissue homogenates and other complex samples. We found that conventional Limulus amebocyte lysate (LAL) assays are not suitable for this purpose due to interference from beta-glucan-like molecules. In contrast, a modified LAL assay that is unaffected by beta-glucan-like molecules was able to detect LPS in infected tissue and in a subset of clinically aseptic tissues. A two-step LAL assay was used to exclude the possibility of false positives due to nonspecific amidases. False positives due to sample color were also excluded, as were false negatives due to assay inhibition. This is the first report to successfully detect LPS in tissue in the absence of overt infection. This approach may be extremely useful in assessing recent hypotheses that subclinical levels of bacteria contribute to a wide range of chronic diseases.     

Interference with simian virus 40 DNA replication by adenovirus type 2 during mixed infection of monkey cells.

Infection of monkey cells with human adenovirus (Ad) is abortive, but the infection can be enhanced by coinfecting with simian virus 40 (SV40). However, in the coinfected monkey cells, Ad interferes strongly with SV40 DNA biosynthesis. This interference was found to be a reproducible, delicately controlled phenomenon that was proportional to the multiplicity of infection of Ad and dependent on the active expression of the Ad genome. Newly synthesized SV40 DNA was not broken down in cells after delayed superinfection with Ad, and several early events of SV40 infection such as adsorption, penetration, uncoating, induction of cellular DNA synthesis, and enhancement of Ad infection were not markedly influenced by Ad-mediated interference. It is unlikely that interference is simply due to competition between SV40 and Ad for metabolites, enzymes, or replication sites. The interference effect could be partially neutralized by an increase in the multiplicity of coinfecting SV40 or by an increase in the time interval between SV40 infection and Ad coinfection. Interference was shown to be due to the activity of an Ad early gene product. However, the detailed mechanism of this Ad interference is still unclear.     

A model for the evolution of pathogen-induced leaf shedding

A size-structured plant population model is developed to study the evolution of pathogen-induced leaf shedding under various environmental conditions. The evolutionary stable strategy (ESS) of the leaf shedding rate is determined for two scenarios: i) a constant leaf shedding strategy and ii) an infection load driven leaf shedding strategy.
The model predicts that ESS leaf shedding rates increase with nutrient availability. No effect of plant density on the ESS leaf shedding rate is found even though disease severity increases with plant density.
When auto-infection, that is increased infection due to spores produced on the plant itself, plays a key role in further disease increase on the plant, shedding leaves removes disease that would otherwise contribute to disease increase on the plant itself. Consequently leaf shedding responses to infections may evolve. When external infection, that is infection due to immigrant spores, is the key determinant, shedding a leaf does not reduce the force of infection on the leaf shedding plant. In this case leaf shedding will not evolve.
Under a low external disease pressure adopting an infection driven leaf shedding strategy is more efficient than adopting a constant leaf shedding strategy, since a plant adopting an infection driven leaf shedding strategy does not shed any leaves in the absence of infection, even when leaf shedding rates are high. A plant adopting a constant leaf shedding rate sheds the same amount of leaves regardless of the presence of infection.
Based on the results we develop two hypotheses that can be tested if the appropriate plant material is available.     

Natural antibodies in Pseudomonas aeruginosa infections

Studying 347 sera of 49 patients suffering from Pseudomonas aeruginosa infection the mean titre value (MTV) calculated from the exponent of the binary logarithm of natural antibody (NA) titres, was found suitable to characterize the humoral immune status. As long as the organism is in equilibrium with the infection, the NA level rises. In septic shock, before death or at the development of a massive infection, the NA titre decreases rapidly. The decrease may be due partly to the permeability increasing effect of endotoxin and antigen-antibody reactions exerted on the capillaries. Consequently, in the most severe phase of sepsis, when bacteria enter the circulation less NA is available to fight against them. This might be a cause of the still very high lethality of septic shock due to Gram-negative bacteria. Finally, when applying the MTV one always has to consider that despite its advantages it gives less information than the Backhausz immunogram.     

Options for the treatment of serious infections with interleukin-1

In this paper, the effects of recombinant human interleukin-1 (IL-1) on non-specific resistance to infection are reviewed. In experiments in neutropenic mice, a single injection of a low dose of IL-1 (8-800 ng) appears to protect against death from lethalPseudomonas aeruginosa andCandida albicans infections. In non-neutropenic mice protection can also be obtained with such dosages of IL-1 in infection caused byKlebsiella pneumoniae orListeria monocytogenes. Low dosages of IL-1 are also able to prevent lethal cerebral malaria in mice. No effect has been found in murine cytomegalovirus infection.With the exception ofC. albicans infection and malaria, protection is only obtained if IL-1 is given before the infection.The mechanism of protection has not been elucidated; in the Pseudomonas and Klebsiella infection, it could be demonstrated that survival was not due to a direct antibacterial effect of IL-1, not due to the action of granulocytes or increased hematopoietic recovery and not due to activation of macrophages and increased bactericidal mechanisms. In the experimental Listeria infection however, animals treated with IL-1 had lower bacterial counts in their organs.Since the cytokines interleukin-6 (IL-6) and tumor necrosis factor (TNF) are much less potent than IL-1 in these protection experiments, it is very unlikely that they are endogenous mediators of the protection induced by IL-1.The effect is not mediated via the cyclooxygenase pathway, since premedication with ibuprofen does not influence the protective effect of IL-l. Taking these data together, it is felt that IL-1 holds promise as a therapeutic agent in humans.     

Spreading disease with transport-related infection

Transportation among regions is found as one of the main factors which affect the outbreak of diseases. It will change the disease dynamics and break infection out even if infectious diseases will go to extinction in each city without transport-related infection. In this paper, a mathematical model is proposed to demonstrate the dynamics of such disease propagation between two regions (or cities) due to the population dispersal and infection on transports. Further, our analysis shows that transport-related infection intensifies the disease spread if infectious diseases break out to cause an endemic situation in each region, in the sense that both the absolute and relative size of patients increase. This suggests that it is very essential to strengthen restrictions of passengers once we know infectious diseases appeared.     

Murine cytomegalovirus infection inhibits tumor necrosis factor alpha responses in primary macrophages

Despite robust host immune responses the betaherpesvirus murine cytomegalovirus (MCMV) is able to establish lifelong infection. This capacity is due at least in part to the virus utilizing multiple immune evasion mechanisms to blunt host responses. Macrophages are an important cell for MCMV infection, dissemination, and latency despite expression in the host of multiple cytokines, including tumor necrosis factor alpha (TNF-alpha), that can induce an antiviral state in macrophages or other cells. In this study, we found that MCMV infection of bone marrow-derived macrophages inhibited TNF-alpha-induced ICAM-1 surface expression and mRNA expression in infected cells via expression of immediate early and/or early viral genes. MCMV infection blocked TNF-alpha-induced nuclear translocation of NF-kappaB. This inhibition of TNF-alpha signaling was explained by a decrease in TNF receptor 1 (TNFR1) and TNFR2 that was due to decreased mRNA for the latter. These findings provide a mechanism by which MCMV can evade the effects of an important host cytokine in macrophages.     

Demographic processes affect HIV-1 evolution in primary infection before the onset of selective processes

HIV-1 transmission and viral evolution in the first year of infection were studied in 11 individuals representing four transmitter-recipient pairs and three independent seroconverters. Nine of these individuals were enrolled during acute infection; all were men who have sex with men (MSM) infected with HIV-1 subtype B. A total of 475 nearly full-length HIV-1 genome sequences were generated, representing on average 10 genomes per specimen at 2 to 12 visits over the first year of infection. Single founding variants with nearly homogeneous viral populations were detected in eight of the nine individuals who were enrolled during acute HIV-1 infection. Restriction to a single founder variant was not due to a lack of diversity in the transmitter as homogeneous populations were found in recipients from transmitters with chronic infection. Mutational patterns indicative of rapid viral population growth dominated during the first 5 weeks of infection and included a slight contraction of viral genetic diversity over the first 20 to 40 days. Subsequently, selection dominated, most markedly in env and nef. Mutants were detected in the first week and became consensus as early as day 21 after the onset of symptoms of primary HIV infection. We found multiple indications of cytotoxic T lymphocyte (CTL) escape mutations while reversions appeared limited. Putative escape mutations were often rapidly replaced with mutually exclusive mutations nearby, indicating the existence of a maturational escape process, possibly in adaptation to viral fitness constraints or to immune responses against new variants. We showed that establishment of HIV-1 infection is likely due to a biological mechanism that restricts transmission rather than to early adaptive evolution during acute infection. Furthermore, the diversity of HIV strains coupled with complex and individual-specific patterns of CTL escape did not reveal shared sequence characteristics of acute infection that could be harnessed for vaccine design.     

Seroprevalence of Severe Fever with Thrombocytopenia Syndrome Phlebovirus in Domesticated Deer in South Korea

Severe fever with thrombocytopenia syndrome phlebovirus(SFTSV) has a wide host range. Not only has it been found in humans, but also in many wild and domesticated animals. The infection of breeding deer on farms is a particularly worrisome public health concern due to the large amount of human contact and the diverse use of deer products, including raw blood. To investigate the prevalence of breeding domesticated deer, we examined the SFTSV infection rate on deer farms in South Korea from 2015 to 2017. Of the 215 collected blood samples, 0.9%(2/215) were found to be positive for viral RNA by PCR, and sequence analysis showed the highest homology with the KADGH human isolate. Both SFTSVspecific recombinant N and Gn protein-based ELISAs revealed that 14.0%(30/215) and 7.9%(17/215) of collected blood specimens were positive for SFTSV antibody. These results demonstrate that the breeding farm deer are exposed to SFTSV and could be a potential infection source for humans through direct contact or consumption of byproducts.     

GBV-B as a pleiotropic virus: distribution of GBV-B in extrahepatic tissues in vivo

GB virus B (GBV-B) infection of New World monkeys is considered to be a useful surrogate model for hepatitis C virus (HCV) infection. GBV-B replicates in the liver and induces acute resolving hepatitis but little is known whether the other organs could be permissive for the virus. We investigated the viral tropism of GBV-B in tamarins in the acute stage of viral infection and found that the viral genomic RNA could be detected in a variety of tissues. Notably, a GBV-B-infected tamarin with marked acute viremia scarcely showed a sign of hepatitis, due to preferential infection in lymphoid tissues such as lymph nodes and spleen. These results indicate that GBV-B as well as HCV is a pleiotropic virus in vivo.     

Innate immune activation during Salmonella infection initiates extramedullary erythropoiesis and splenomegaly

Systemic Salmonella infection commonly induces prolonged splenomegaly in murine or human hosts. Although this increase in splenic cellularity is often assumed to be due to the recruitment and expansion of leukocytes, the actual cause of splenomegaly remains unclear. We monitored spleen cell populations during Salmonella infection and found that the most prominent increase is found in the erythroid compartment. At the peak of infection, the majority of spleen cells are immature CD71(-)Ter119(+) reticulocytes, indicating that massive erythropoiesis occurs in response to Salmonella infection. Indeed, this increase in RBC precursors corresponded with marked elevation of serum erythropoietin (EPO). Furthermore, the increase in RBC precursors and EPO production required innate immune signaling mediated by Myd88/TRIF. Neutralization of EPO substantially reduced the immature RBC population in the spleen and allowed a modest increase in host control of infection. These data indicate that early innate immunity to Salmonella initiates marked splenic erythropoiesis and may hinder bacterial clearance.     

Study of brain and vascular plexus gangliosides in meningoencephalitis of various etiology.

The content of brain and vascular plexus gangliosides and their composition have been studied in 15 cases of meningoencephalitis of various etiology and degree of disease. The most pronounced decrease of ganglioside concentration was found in brain of children, who died from herpes virus infection. Decrease of ganglioside content was revealed in brain grey matter of patients with influenza virus or meningococcus infection, but not in cases of mycoplasma infection. These data provide evidence of nerve cell destruction due to meningoencephalitis of various etiology. The biochemical data obtained are in good agreement with the results of the brain of children infection by herpes virus (increase of GD1b content in grey matter). Ganglioside content in vascular plexes of patients with meningoencephalitis was found to be, on the contrary, much higher (ca 4 times) than in the controls. The higher the lesion of choroid plexes in meningoencephalitis is, the higher the ganglioside content in them is.     

Age-Related Relationships between Innate Immunity and Plasma Carotenoids in an Obligate Avian Scavenger

Variation in immunity is influenced by allocation trade-offs that are expected to change between age-classes as a result of the different environmental and physiological conditions that individuals encounter over their lifetime. One such trade-off occurs with carotenoids, which must be acquired with food and are involved in a variety of physiological functions. Nonetheless, relationships between immunity and carotenoids in species where these micronutrients are scarce due to diet are poorly studied. Among birds, vultures show the lowest concentrations of plasma carotenoids due to a diet based on carrion. Here, we investigated variations in the relationships between innate immunity (hemagglutination by natural antibodies and hemolysis by complement proteins), pathogen infection and plasma carotenoids in nestling and adult griffon vultures (Gyps fulvus) in the wild. Nestlings showed lower hemolysis, higher total carotenoid concentration and higher pathogen infection than adults. Hemolysis was negatively related to carotenoid concentration only in nestlings. A differential carotenoid allocation to immunity due to the incomplete development of the immune system of nestlings compared with adults is suggested linked to, or regardless of, potential differences in parasite infection, which requires experimental testing. We also found that individuals with more severe pathogen infections showed lower hemagglutination than those with a lower intensity infection irrespective of their age and carotenoid level. These results are consistent with the idea that intraspecific relationships between innate immunity and carotenoids may change across ontogeny, even in species lacking carotenoid-based coloration. Thus, even low concentrations of plasma carotenoids due to a scavenger diet can be essential to the development and activation of the immune system in growing birds.     

Inhibition of Phage Growth by an Antibiotic Rugulosin Isolated from Myrothecium verucaria

It was found that (?)rugulosin, an antibiotic isolated from Myrothecium verucaria, had a potent anti-phage effect on RNA phages (MS2, GA and Qβ) and DNA phages (δA and T4). The effect was almost independent of the host bacterial strains used. By a detailed investigation using MS2, it was revealed that the antibiotic did not affect the free phage or host bacterium alone but inhibited phage multiplication, and the degree of the inhibition depended on the multiplicity of infection. The inhibition was not mainly due to a drop in the burst size but rather was due to a decrease of the phage-producing cells during the early stages of phage infection and replication.     

Activation of superoxide dismutase in selenium-deficient mice infected with influenza virus.

Selenium (Se) deficiency is associated with decreased activities of Se-dependent antioxidant enzymes, glutathione peroxidase (GPx) and thioredoxin reductase (TR), and with changes in the cellular redox status. We have previously shown that host Se deficiency is responsible for increased virulence of influenza virus in mice due to changes in the viral genome. The present study examines the antioxidant defense systems in the lung and liver of Se-deficient and Se-adequate mice infected with influenza A/Bangkok/1/79. Results show that neither Se status nor infection changed glutathione (GSH) concentration in the lung. Hepatic GSH concentration was lower in Se-deficient mice, but increased significantly day 5 post infection. No significant differences due to Se status or influenza infection were found in catalase activities. As expected, Se deficiency was associated with significant decreases in GPx and TR activities in both lung and liver. GPx activity increased in the lungs and decreased in the liver of Se-adequate mice in response to infection. Both Se deficiency and influenza infection had profound effects on the activity of superoxide dismutase (SOD). The hepatic SOD activity was higher in Se-deficient than Se-adequate mice before infection. However, following influenza infection, hepatic SOD activity in Se-adequate mice gradually increased. Influenza infection was associated with a significant increase of SOD activity in the lungs of Se-deficient, but not Se-adequate mice. The maximum of SOD activity coincided with the peak of pathogenesis in infected lungs. These data suggest that SOD activation in the lung and liver may be a part of a compensatory response to Se deficiency and/or influenza infection. However, SOD activation that leads to increased production of H(2)O(2) may also contribute to pathogenesis and to influenza virus mutation in lungs of Se-deficient mice.     

Wolbachia in a major African crop pest increases susceptibility to viral disease rather than protects

Wolbachia are common vertically transmitted endosymbiotic bacteria found in < 70% of insect species. They have generated considerable recent interest due to the capacity of some strains to protect their insect hosts against viruses and the potential for this to reduce vector competence of a range of human diseases, including dengue. In contrast, here we provide data from field populations of a major crop pest, African armyworm (Spodoptera exempta), which show that the prevalence and intensity of infection with a nucleopolydrovirus (SpexNPV) is positively associated with infection with three strains of Wolbachia. We also use laboratory bioassays to demonstrate that infection with one of these strains, a male-killer, increases host mortality due to SpexNPV by 6-14 times. These findings suggest that rather than protecting their lepidopteran host from viral infection, Wolbachia instead make them more susceptible. This finding potentially has implications for the biological control of other insect crop pests.     

Cytomegalovirus in the mononucleosis syndrome in children

In 7 children aged 18 months to 7 years isolated from a group of 128 children with infectious mononucleosis the cytomegalovirus infection was found. Infection was diagnosed by determination of antibodies against immediate early and late CMV antigen by means of the ELISA test. Besides that, antibodies were determined against the capsid antigen and early antigen of EB virus by the method of indirect immunofluorescence. In four children only cytomegalovirus infection was found and three had a mixed infection with both viruses and the diagnosis in these cases was: infectious mononucleosis (due to EBV) with coexistent or following CMV infection. In the sera of two children with cytomegalovirus mononucleosis changes were observed in the antibodies against EBV which is explained as a result of interactions between CMV and EBV in the organism of the host.     

Nocardia cyriacigeorgica is a significant pathogen responsible for nocardiosis in Japan and Thailand

Nocardia cyriacigeorgica is a recently described species. During routine diagnostic testing of 121 clinical isolates, we found that about one fourth of the strains from Japan (19 isolates) and Thailand (8 isolates), which were identified in our laboratories as N. asteroides, in fact belong to N. cyriacigeorgica. To our knowledge, this is the first report of infection due to N. cyriacigeorgica in Japan and Thailand, and the third report of infection anywhere in the world. Although N. cyriacigeorgica is usually differentiated from other Nocardia species by utilization of glucose and gluconate, we found that it can also be differentiated by a characteristic synergistic effect between imipenem (IPM) and tobramycin (TOB).     

Epstein-Barr virus can establish infection in the absence of a classical memory B-cell population

Epstein-Barr virus (EBV) is a ubiquitous human herpesvirus that persists in the body for life after primary infection. The primary site of EBV persistence is the memory B lymphocyte, but whether the virus initially infects na?ve or memory B cells is still disputed. We have analyzed EBV infection in nine cases of X-linked hyper-immunoglobulin M (hyper-IgM) syndrome who, due to a mutation in CD40 ligand gene, do not have a classical, class-switched memory B-cell population (IgD(-) CD27(+)). We found evidence of EBV infection in 67% of cases, which is similar to the infection rate found in the general United Kingdom population (60 to 70% for the relevant age range). We detected EBV DNA in peripheral blood B cells and showed in one case that the infection was restricted to the small population of nonclassical, germinal center-independent memory B cells (IgD(+) CD27(+)). Detection of EBV small RNAs, latent membrane protein 2, and EBV nuclear antigen 3C expression in peripheral blood suggests full latent viral gene expression in this population. Analysis of EBV DNA in serial samples showed variability over time, suggesting cycles of infection and loss. Our results demonstrate that short-term EBV persistence can occur in the absence of a germinal center reaction and a classical memory B-cell population.