Antibodies to selected viral and bacterial pathogens in European wild boars from southcentral Spain

Serum samples from 78 European wild boars (Sus scrofa) harvested during the 1999-2000 hunting season were tested for antibodies to Brucella spp., classical swine fever virus, Erysipelothrix rhusiopathiae, Haemophilus parasuis, Leptospira interrogans serovar pomona, Mycoplasma hyopneumoniae, pseudorabies virus (PRV), porcine parvovirus (PPV), porcine reproductive and respiratory syndrome virus, Salmonella serogroups B, C, and D, Streptococcus suis, and swine influenza virus (SIV) serotypes H1N1 and H3N2. Samples were collected from Sierra Morena and Montes de Toledo in southcentral Spain. Antibodies were detected to PRV (36%), L. interrogans serovar pomona (12%), PPV (10%), E. rhusiopathiae (5%), SIV serotype H1N1 (4%), Salmonella serogroup B (4%), and Salmonella serogroup C (3%). Our results suggest that more research is needed to describe the epidemiology of infectious diseases of Spanish wild boars.     

A serologic survey of pronghorns in Alberta and Saskatchewan, 1970-1972.

To determine the exposure of free-ranging pronghorns (Antilocapra americana Ord) to selected pathogens, serum samples were obtained from 33 live-trapped animals from southwestern Saskatchewan in 1970, and from 26 and 51 animals from southeastern Alberta, in 1971 and 1972, respectively. Antibodies were found to the agents of parainfluenza 3, bovine virus diarrhea, eastern and western encephalomyelitis, infectious bovine rhinotracheitis and the chlamydial group. No serologic reactors were found to the agents of bluetongue, epizootic hemorrhagic disease, brucellosis, or leptospirosis (4 serotypes).     

Endogenous MMTV proviruses induce susceptibility to both viral and bacterial pathogens

Most inbred mice carry germline proviruses of the retrovirus, mouse mammary tumor virus (MMTV) (called Mtvs), which have multiple replication defects. A BALB/c congenic mouse strain lacking all endogenous Mtvs (Mtv-null) was resistant to MMTV oral and intraperitoneal infection and tumorigenesis compared to wild-type BALB/c mice. Infection of Mtv-null mice with an MMTV-related retrovirus, type B leukemogenic virus, also resulted in severely reduced viral loads and failure to induce T-cell lymphomas, indicating that resistance is not dependent on expression of a superantigen (Sag) encoded by exogenous MMTV. Resistance to MMTV in Mtv-null animals was not due to neutralizing antibodies. Further, Mtv-null mice were resistant to rapid mortality induced by intragastric inoculation of the Gram-negative bacterium, Vibrio cholerae, but susceptibility to Salmonella typhimurium was not significantly different from BALB/c mice. Susceptibility to both MMTV and V. cholerae was reconstituted by the presence of any one of three endogenous Mtvs located on different chromosomes and was associated with increased pathogen load. One of these endogenous proviruses is known to encode only Sag. Therefore, Mtv-encoded Sag appears to provide a unique genetic susceptibility to specific viruses and bacteria. Since human endogenous retroviruses also encode Sags, these studies have broad implications for pathogen-induced responses in mice and humans.     

Serosurvey for selected pathogens in hunter-killed pronghorns in western Nebraska

Exposure of pronghorns (Antilocapra americana) in western Nebraska in 1983 to selected livestock pathogens was examined by serology and attempted virus isolation. Antibodies were present to the agents of bluetongue, epizootic hemorrhagic disease, and bovine respiratory syncytial virus. There were no serologic reactors to Brucella, and attempts to isolate the viruses of bluetongue and epizootic hemorrhagic disease were negative.     

The role of viral and bacterial pathogens in gastrointestinal cancer

The association of Helicobacter pylori (H. pylori) with gastric cancer is thus far the best understood model to comprehend the causal relationship between a microbial pathogen and cancer in the human gastrointestinal tract. Besides H. pylori, a variety of other pathogens are now being recognized as potential carcinogens in different settings of human cancer. In this context, viral causes of human cancers are central to the issue since these account for 10-20% of cancers worldwide. In the case of H. pylori and gastric cancer, as well as the human papillomavirus and anal cancer, the causal relationship between the infectious agent and the related cancer in the gastrointestinal tract has been clearly confirmed by epidemiological and experimental studies. Similarly, Epstein-Barr virus and the oncogenic JC virus are being suggested as possible causative agents for cancers in the upper and lower gastrointestinal tract. This review discusses various viral and microbial pathogens and their oncogenic properties in the evolution of gastrointestinal carcinogenesis and summarizes the available experimental data make a convincing agreement favoring the associations between infectious agents and specific human cancers.     

Modulation of inflammasome pathways by bacterial and viral pathogens

Inflammasomes are emerging as key regulators of the host response against microbial pathogens. These cytosolic multiprotein complexes recruit and activate the cysteine protease caspase-1 when microbes invade sterile tissues or elicit cellular damage. Inflammasome-activated caspase-1 induces inflammation by cleaving the proinflammatory cytokines IL-1β and IL-18 into their biologically active forms and by releasing the alarmin HMGB1 into the extracellular milieu. Additionally, inflammasomes counter bacterial replication and clear infected immune cells through an inflammatory cell death program termed pyroptosis. As a countermeasure, bacterial and viral pathogens evolved virulence factors to antagonize inflammasome pathways. In this review, we discuss recent progress on how inflammasomes contribute to host defense against bacterial and viral pathogens, and we review how viruses and bacteria modulate inflammasome function to their benefit.     

Large scale comparison of innate responses to viral and bacterial pathogens in mouse and macaque

Viral and bacterial infections of the lower respiratory tract are major causes of morbidity and mortality worldwide. Alveolar macrophages line the alveolar spaces and are the first cells of the immune system to respond to invading pathogens. To determine the similarities and differences between the responses of mice and macaques to invading pathogens we profiled alveolar macrophages from these species following infection with two viral (PR8 and Fuj/02 influenza A) and two bacterial (Mycobacterium tuberculosis and Francisella tularensis Schu S4) pathogens. Cells were collected at 6 time points following each infection and expression profiles were compared across and between species. Our analyses identified a core set of genes, activated in both species and across all pathogens that were predominantly part of the interferon response pathway. In addition, we identified similarities across species in the way innate immune cells respond to lethal versus non-lethal pathogens. On the other hand we also found several species and pathogen specific response patterns. These results provide new insights into mechanisms by which the innate immune system responds to, and interacts with, invading pathogens.     

The phylogenetic range of bacterial and viral pathogens of vertebrates

Many major human pathogens are multihost pathogens, able to infect other vertebrate species. Describing the general patterns of host–pathogen associations across pathogen taxa is therefore important to understand risk factors for human disease emergence. However, there is a lack of comprehensive curated databases for this purpose, with most previous efforts focusing on viruses. Here, we report the largest manually compiled host–pathogen association database, covering 2,595 bacteria and viruses infecting 2,656 vertebrate hosts. We also build a tree for host species using nine mitochondrial genes, giving a quantitative measure of the phylogenetic similarity of hosts. We find that the majority of bacteria and viruses are specialists infecting only a single host species, with bacteria having a significantly higher proportion of specialists compared to viruses. Conversely, multihost viruses have a more restricted host range than multihost bacteria. We perform multiple analyses of factors associated with pathogen richness per host species and the pathogen traits associated with greater host range and zoonotic potential. We show that factors previously identified as important for zoonotic potential in viruses—such as phylogenetic range, research effort, and being vector‐borne—are also predictive in bacteria. We find that the fraction of pathogens shared between two hosts decreases with the phylogenetic distance between them. Our results suggest that host phylogenetic similarity is the primary factor for host‐switching in pathogens.     

Cytosolic lipid inclusions formed during infection by viral and bacterial pathogens

Lipid inclusions play an important role in several pathological processes. Intracellular bacterial pathogens, such as members of the Mycobacterium and Chlamydia species are able to trigger the formation of lipid-laden foamy macrophages. Lipid droplet accumulation in the host constitutes a reservoir used by the bacilli for long-term persistence. Viruses need lipid droplets as assembly platform. We present the current knowledge about structural, functional and regulatory aspects of lipid inclusions.     

Chalcogenoxanthylium photosensitizers for the photodynamic purging of blood-borne viral and bacterial pathogens

Thio- and selenoxanthylium dyes were prepared by the addition of 2-lithiothiophene, 4-N,N-dimethylaminophenylmagnesium bromide, and 1-naphthylmagnesium bromide to the appropriate 2,7-bis-N,N-dimethylaminochalcogenoxanthen-9-one, followed by dehydration and ion exchange to the chloride salts. The corresponding chalcogenoxanthylium dyes were evaluated as photosensitizers for the inactivation of intracellular and extracellular virus in red blood cell suspensions and for the inactivation of selected strains of gram (+) and gram (-) bacteria in red blood cell suspensions. Selected combinations of photosensitizer and light gave >6 log10 inactivation of intracellular and extracellular virus, and >4 log10 inactivation of extracellular bacteria with varying levels of hemolyis, following a 42-day storage of red blood cell suspensions. Photocleavage experiments with plasmid DNA and the chalcogenoxanthylium dyes suggested the genomic material contained in the virus and in the bacteria as one possible target for the photodynamic action of some of these dyes.     

Expression of the bacterial gene CspD in tobacco plants increases their resistance to fungal and viral pathogens

Low molecular (7.2 kD) cold shock protein D (CspD) from Bacillus thuringiensis was isolated in our laboratory in the late 1990s It was shown that CspD induced nonspecific resistance in plants to viral and fungal phytopathogens. It was suggested to explore the opportunity to express the gene of this elicitor in tobacco plant and evaluate the resistance ofthe transgenic plants to various pathogens. Several transgenic tobacco lines were obtained. Enhanced resistance of the transgenic plants was confirmed both to tobacco mosaic virus and to fungus Alternaria longipes.     

Anti-immunology: evasion of the host immune system by bacterial and viral pathogens

Multicellular organisms possess very sophisticated defense mechanisms that are designed to effectively counter the continual microbial insult of the environment within the vertebrate host. However, successful microbial pathogens have in turn evolved complex and efficient methods to overcome innate and adaptive immune mechanisms, which can result in disease or chronic infections. Although the various virulence strategies used by viral and bacterial pathogens are numerous, there are several general mechanisms that are used to subvert and exploit immune systems that are shared between these diverse microbial pathogens. The success of each pathogen is directly dependant on its ability to mount an effective anti-immune response within the infected host, which can ultimately result in acute disease, chronic infection, or pathogen clearance. In this review, we highlight and compare some of the many molecular mechanisms that bacterial and viral pathogens use to evade host immune defenses.     

Co-occurrence of viral and bacterial pathogens in disease outbreaks affecting newly cultured sparid fish.

Several microbial disease outbreaks in farm stocks of newly cultured sparid fish species, such as common seabream, redbanded seabream, and white seabream, were recorded from 2004 to 2006. This study describes the isolation and characterization of the potential causative agents, either bacteria or viruses, of these outbreaks. The isolated bacterial strains were characterized according to traditional taxonomical analyses and sequencing of a 16S rDNA fragment. Most bacteria were identified as Vibrio spp. and Photobacterium damselae subsp. damselae. The development of cytopathic effects (CPE) on different fish cell lines, the application of specific nested-PCR tests for infectious pancreatic necrosis virus (IPNV), viral nervous necrosis virus (VNNV) and viral hemorrhagic septicemia virus (VHSV), and subsequent sequence analyses were used for virus detection and identification. VNNV, related to the striped jack neural necrosis virus (SJNNV) genotype, and VHSV, related to the genotype Ia, were the only viruses detected. VNNV was isolated from the three fish species under study in five different outbreaks, whereas VHSV was isolated from common seabream and white seabream during two of these outbreaks. IPNV was not detected in any case.     

Intracellular innate resistance to bacterial pathogens

Mammalian innate immunity stimulates antigen-specific immune responses and acts to control infection prior to the onset of adaptive immunity. Some bacterial pathogens replicate within the host cell and are therefore sheltered from some protective aspects of innate immunity such as complement. Here we focus on mechanisms of innate intracellular resistance encountered by bacterial pathogens and how some bacteria can evade destruction by the innate immune system. Major strategies of intracellular antibacterial defence include pathogen compartmentalization and iron limitation. Compartmentalization of pathogens within the host endocytic pathway is critical for generating high local concentrations of antimicrobial molecules, such as reactive oxygen species, and regulating concentrations of divalent cations that are essential for microbial growth. Cytosolic sensing, autophagy, sequestration of essential nutrients and membrane attack by antimicrobial peptides are also discussed.     

Respiratory viruses augment the adhesion of bacterial pathogens to respiratory epithelium in a viral species- and cell type-dependent manner

Secondary bacterial infections often complicate respiratory viral infections, but the mechanisms whereby viruses predispose to bacterial disease are not completely understood. We determined the effects of infection with respiratory syncytial virus (RSV), human parainfluenza virus 3 (HPIV-3), and influenza virus on the abilities of nontypeable Haemophilus influenzae and Streptococcus pneumoniae to adhere to respiratory epithelial cells and how these viruses alter the expression of known receptors for these bacteria. All viruses enhanced bacterial adhesion to primary and immortalized cell lines. RSV and HPIV-3 infection increased the expression of several known receptors for pathogenic bacteria by primary bronchial epithelial cells and A549 cells but not by primary small airway epithelial cells. Influenza virus infection did not alter receptor expression. Paramyxoviruses augmented bacterial adherence to primary bronchial epithelial cells and immortalized cell lines by up-regulating eukaryotic cell receptors for these pathogens, whereas this mechanism was less significant in primary small airway epithelial cells and in influenza virus infections. Respiratory viruses promote bacterial adhesion to respiratory epithelial cells, a process that may increase bacterial colonization and contribute to disease. These studies highlight the distinct responses of different cell types to viral infection and the need to consider this variation when interpreting studies of the interactions between respiratory cells and viral pathogens.     

Pinellia ternata agglutinin expression in chloroplasts confers broad spectrum resistance against aphid, whitefly, Lepidopteran insects, bacterial and viral pathogens

Broad spectrum protection against different insects and pathogens requires multigene engineering. However, such broad spectrum protection against biotic stress is provided by a single protein in some medicinal plants. Therefore, tobacco chloroplasts were transformed with the agglutinin gene from Pinellia ternata (pta), a widely cultivated Chinese medicinal herb. Pinellia ternata agglutinin (PTA) was expressed up to 9.2% of total soluble protein in mature leaves. Purified PTA showed similar hemagglutination activity as snowdrop lectin. Artificial diet with purified PTA from transplastomic plants showed marked and broad insecticidal activity. In planta bioassays conducted with T0 or T1 generation PTA lines showed that the growth of aphid Myzus persicae (Sulzer) was reduced by 89%-92% when compared with untransformed (UT) plants. Similarly, the larval survival and total population of whitefly (Bemisia tabaci) on transplastomic lines were reduced by 91%-93% when compared with UT plants. This is indeed the first report of lectin controlling whitefly infestation. When transplastomic PTA leaves were fed to corn earworm (Helicoverpa zea), tobacco budworm (Heliothis virescens) or the beet armyworm (spodoptera exigua), 100% mortality was observed against all these three insects. In planta bioassays revealed Erwinia population to be 10,000-fold higher in control than in PTA lines. Similar results were observed with tobacco mosaic virus (TMV) challenge. Therefore, broad spectrum resistance to homopteran (sap-sucking), Lepidopteran insects as well as anti-bacterial or anti-viral activity observed in PTA lines provides a new option to engineer protection against biotic stress by hyper-expression of an unique protein that is naturally present in a medicinal plant.