Wide Variety Of Potential Pathogens Research Articles

European Starlings (Sturnus vulgaris) as Vectors and Reservoirs of Pathogens Affecting Humans and Domestic Livestock

Simple SummaryEuropean starlings are an abundant, widespread avian species frequently found in close association with human development and agriculture. Do starlings play a role in transmitting disease to humans or domestic livestock? To investigate the importance of European starlings as disease vectors, I reviewed and assessed the available literature, comprising several hundred published papers. Although a wide variety of potential pathogens have been reported in starlings, the strongest evidence suggests that they may be responsible for harboring and dispersing some species of enteric bacteria, with Escherichia coli and Campylobacter jejuni of perhaps greatest interest, and primarily in the context of dairies, concentrated animal feeding operations, and other intensive livestock agriculture. Although they can carry other pathogens like Salmonella and influenza viruses, evidence suggests they are not as important in the ecology of these diseases.European starlings are an abundant, widespread avian species frequently found in close association with human development and agriculture. The ability of starlings to carry and disperse pathogens of humans and domesticated livestock has received considerable attention, including studies of enteric bacteria, viruses, and some fungi. To investigate the importance of European starlings as disease vectors, I reviewed and assessed the available literature, comprising several hundred published papers. Although a wide variety of potential pathogens have been reported in starlings, the strongest evidence suggests that they may be responsible for harboring and dispersing some species of enteric bacteria, with Escherichia coli and Campylobacter jejuni of perhaps greatest interest, and primarily in the context of dairies, concentrated animal feeding operations, and other intensive livestock agriculture.

RELAPSING POLYCHONDRITIS IN RHEUMATOLOGY PRACTICE

The paper provides a clinical description of relapsing polychondritis, a rare systemic immunoinflammatory disease that was characterized by fever episodes, cartilage damage, and reactive arthritis. Diagnostic searching could rule out an infectious disease (by determining a wide variety of potential pathogens), as well as a septic condition due to a pronounced leukemoid reaction of the myeloid type, and the presence of toxigenic neutrophil granulation in peripheral blood and bone marrow. All available clinical, functional, and radiological studies were used to make a differential diagnosis with paraneoplastic syndrome due to blood disease, primarily with myeloma. The data obtained could interpret the changes only as reactive. No increased autoantibody titers were identified. Clinical symptoms and the good effect of prednisolone therapy allowed a diagnosis of relapsing polychondritis, a rare disease that belongs to the group of immunoinflammatory diseases according to the current ideas. It is suggested that autoinflammation plays a role in its pathogenesis.

Early immune events in the induction of allergic contact dermatitis

The skin is a barrier site that is exposed to a wide variety of potential pathogens. As in other organs, pathogens that invade the skin are recognized by pattern-recognition receptors (PRRs). Recently, it has been recognized that PRRs are also engaged by chemical contact allergens and, in susceptible individuals, this elicits an inappropriate immune response that results in allergic contact dermatitis. In this Review, we focus on how contact allergens promote inflammation by activating the innate immune system. We also examine how innate immune cells in the skin, including mast cells and dendritic cells, cooperate with each other and with T cells and keratinocytes to initiate and drive early responses to contact allergens.

Native Properdin Binds toChlamydia pneumoniaeand Promotes Complement Activation

Activation of complement represents one means of natural resistance to infection from a wide variety of potential pathogens. Recently, properdin, a positive regulator of the alternative pathway of complement, has been shown to bind to surfaces and promote complement activation. Here we studied whether properdin-mediated complement activation occurs on the surface of Chlamydia pneumoniae, an obligate intracellular Gram-negative bacterium that causes 10 to 20% of community-acquired pneumonia. We have determined for the first time that the physiological P₂, P₃, and P₄ forms of human properdin bind to the surface of Chlamydia pneumoniae directly. The binding of these physiological forms accelerates complement activation on the Chlamydia pneumoniae surface, as measured by C3b and C9 deposition. Finally, properdin-depleted serum could not control Chlamydia pneumoniae infection of HEp-2 cells compared with normal human serum. However, after addition of native properdin, the properdin-depleted serum recovered the ability to control the infection. Altogether, our data suggest that properdin is a pattern recognition molecule that plays a role in resistance to Chlamydia infection.

Complement activation on Chlamydia pneumoniae is accelerated by direct binding of native properdin to its surface (37.10)

Abstract Activation of complement represents one means of natural resistance to infection from a wide variety of potential pathogens. Recently properdin, a positive regulator of the alternative pathway of complement, has been shown to bind to surfaces and activate complement de novo. Here we studied the molecular mechanisms of properdin-mediated complement activation on Chlamydia pneumoniae, an obligate intracellular gram-negative bacterium that causes upper respiratory tract infections. We analyzed the ability of properdin to initiate complement activation by binding to C. pneumoniae directly, providing a platform for de novo convertase assembly. We determined for the first time that the physiological P2-P4 forms of human properdin bind to the surface of C. pneumoniae. The binding of these physiological forms initiates and accelerates complement activation on the C. pneumoniae surface, as measured by C3b and C9 deposition. Finally, properdin-depleted serum could not control C. pneumoniae infection of HEp-2 cells when compared with normal human serum. However, addition of native properdin to properdin depleted serum recovered the ability of serum to control the infection. Altogether, our data suggest that properdin is a pattern recognition molecule that plays a role in resistance to Chlamydia infection.

Structural and Functional Aspects of the Collectin SP-A

Surfactant protein A (SP-A), member of the collectin family, is implicated in innate host defense of the lung. SP-A is a "pattern recognition molecule" and interacts with glycoconjugates on the surface of micro-organisms. It protects the lung by interacting with a wide variety of potential pathogens, including viruses, bacteria and fungi. This may result in enhanced killing and clearance by phagocytes. SP-A is a link between the innate and adaptive immune system because it directly affects lymphocyte proliferation and function. Although most extensively studied in the lung, SP-A is found in a number of other sites in the body. The presence of SP-A at these mucosal surfaces, which are in close contact with numerous potentially harmful micro-organisms, supports a more general role for this collectin in mucosal defense.

Localization and Functions of SP-A and SP-D at Mucosal Surfaces

Pulmonary surfactant protein A (SP-A) and D (SP-D), members of the collectin family, are implicated in innate host defense of the lung. Collectins consist of a collagen-like domain and a carbohydrate recognition domain. SP-A and SP-D recognize and interact with glycoconjugates on the surface of microorganisms. They protect the lung by interacting with a wide variety of potential pathogens, including viruses, bacteria, and fungi. This may result in enhanced killing and/or clearance by phagocytes. Although most extensively studied in the lung, both SP-A and SP-D, or proteins closely resembling SP-A and SP-D, are found in a number of other sites in the body and therefore may play a protective role at other sites than the lung. SP-A and SP-D protein and/or mRNA have been detected at various sites of the body: the respiratory tract, the gastrointestinal tract, the middle ear, and in the peritoneal cavity. The presence of SP-A and SP-D at these mucosal surfaces, in close contact with numerous potentially harmful microorganisms, supports a role for these "lung"-collectins in innate mucosal defense. SP-A and SP-D may be important molecules in a threefold innate defense, particularly in the neonatal period between maternally acquired immunity and a fully developed adaptive immune system; the time interval between first exposure to a pathogen and generation of specific antibodies; and states of impaired immune function.

Functional Roles of the Lung Surfactant Proteins SP-A and SP-D in Innate Immunity

The surfactant proteins SP-A and SP-D are known to play important roles in innate immunity in the lungs in the protection against a wide variety of potential pathogens, which include viruses, bacteria and fungi. Recognition of the pathogens is, in most cases, mediated by the Ca +2-dependent binding of the C-type lectin domains of SP-A, or SP-D, to carbohydrate structures on the surface of the microorganisms. This can cause agglutination of the pathogens and also possibly their enhanced killing and clearance by phagocytic cells which carry receptors for SP-A or SP-D. Both SP-A and SP-D are found in a number of other sites in the body, in various secretions, and therefore may play a wider protective role than was initially envisaged.

Discrimination between activators and nonactivators of the alternative pathway of complement: regulation via a sialic acid/polyanion binding site on factor H.

The alternative complement pathway is capable of discriminating human cells and tissues from a wide variety of potential pathogens. It has been recently demonstrated that attachment of complement component C3b to activator-derived molecules (e.g., small polysaccharides) restricts inactivation of C3b by factors H and I in a manner similar to activator surfaces. It is now shown that restriction is reversed by certain soluble polyanions (e.g., sialoglycopeptides, heparin, or dextran sulfate) that mimic the effects of sialic acid and glycosaminoglycans on human cells and tissues. Fluid-phase polyanions enhanced binding of factor H to C3b attached to activating particles, indicating that the effect resulted from increased affinity between C3b and factor H. The enhancement was specific for activator-bound C3b since no enhancement was observed on nonactivating particles. While several polyanions could cause this effect, some polyanions could not, indicating specificity. The active polyanions also inhibited lysis of cells via the alternative pathway. The binding site for sialic acid appears to reside on factor H, since factor H bound to heparin-agarose and to sialic acid-bearing fetuinagarose, whereas C3b bound to neither under the same conditions. These observations suggest that occupation of a specific site on factor H by polyanions induces an increase in the C3b-H affinity, resulting in discrimination of host cells and tissues from alternative pathway-activating foreign cells.

Latest Developments in the Enzyme-Linked Immunosorbent Assay (ELISA)

Enzyme-linked immunosorbent assays (ELISAs) for the serologic detection of both antigen and antibody in monitoring programs of commercial poultry flocks have begun to be recognized as an improvement over more conventional diagnostic procedures. The feasibility of employing double-antibody sandwich assays for the detection of virus without prior isolation of virus has been demonstrated and shows promise as the method of choice for the detection of lymphoid leukosis virus shedding. The versatility of indirect ELISA for the measurement of antibody induced by a wide variety of potential pathogens using a single basic overlapping ELISA system has also been demonstrated. It shows potential as a likely candidate to replace some of the more costly and time-consuming or less sensitive conventional serologic methods that do not overlap. Although some aspects of the two major types of immunoassays currently used in poultry health may need some modifications or improvements before delivery for routine use, it is likely that the use of computer-assisted ELISA will gain increased acceptance and use as the preferred way to efficiently and accurately monitor the health of poultry flocks on a broad scale.