Faculty Opinions recommendation of A possible cluster of sexually transmitted Entamoeba histolytica: genetic analysis of a highly virulent strain.

ABSTRACTProtective antigen (PA)-based anthrax vaccines acting on toxins are less effective than live attenuated vaccines, suggesting that additional antigens may contribute to protective immunity. Several reports indicate that capsule or spore-associated antigens may enhance the protection afforded by PA. Addition of formaldehyde-inactivated spores (FIS) to PA (PA-FIS) elicits total protection against cutaneous anthrax. Nevertheless, vaccines that are effective against cutaneous anthrax may not be so against inhalational anthrax. The aim of this work was to optimize immunization with PA-FIS and to assess vaccine efficacy against inhalational anthrax. We assessed the immune response to recombinant anthrax PA fromBacillus anthracis(rPA)-FIS administered by various immunization protocols and the protection provided to mice and guinea pigs infected through the respiratory route with spores of a virulent strain ofB. anthracis. Combined subcutaneous plus intranasal immunization of mice yielded a mucosal immunoglobulin G response to rPA that was more than 20 times higher than that in lung mucosal secretions after subcutaneous vaccination. The titers of toxin-neutralizing antibody and antispore antibody were also significantly higher: nine and eight times higher, respectively. The optimized immunization elicited total protection of mice intranasally infected with the virulentB. anthracisstrain 17JB. Guinea pigs were fully protected, both against an intranasal challenge with 100 50% lethal doses (LD50) and against an aerosol with 75 LD50of spores of the highly virulent strain 9602. Conversely, immunization with PA alone did not elicit protection. These results demonstrate that the association of PA and spores is very much more effective than PA alone against experimental inhalational anthrax.

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Cytokine expression in the liver of mice infected with a highly virulent strain ofFrancisella tularensis

FEMS Immunology & Medical Microbiology ◽

10.1111/j.1574-695x.1996.tb00244.x ◽

1996 ◽

Vol 13 (3) ◽

pp. 239-244 ◽

Cited By ~ 25

Author(s):

Igor Golovliov ◽

Kerstin Kuoppa ◽

Anders Sjöstedt ◽

Arne Tärnvik ◽

Gunnar Sandström

Keyword(s):

Virulent Strain ◽

Cytokine Expression ◽

Highly Virulent

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Analysis of Virus Population Profiles within Pigs Infected with Virulent Classical Swine Fever Viruses: Evidence for Bottlenecks in Transmission but Absence of Tissue-Specific Virus Variants

Journal of Virology ◽

10.1128/jvi.01119-20 ◽

2020 ◽

Vol 94 (19) ◽

Author(s):

Camille Melissa Johnston ◽

Ulrik Fahnøe ◽

Louise Lohse ◽

Jens Bukh ◽

Graham J. Belsham ◽

...

Keyword(s):

Classical Swine Fever Virus ◽

Population Change ◽

Virulent Strain ◽

Severe Disease ◽

Clinical Signs ◽

Classical Swine Fever ◽

Fever Virus ◽

Host Cells ◽

Virus Population ◽

Highly Virulent

ABSTRACT Classical swine fever virus (CSFV) contains a specific motif within the E2 glycoprotein that differs between strains of different virulence. In the highly virulent CSFV strain Koslov, this motif comprises residues S763/L764 in the polyprotein. However, L763/P764 represent the predominant alleles in published CSFV genomes. In this study, changes were introduced into the CSFV strain Koslov (here called vKos_SL) to generate modified CSFVs with substitutions at residues 763 and/or 764 (vKos_LL, vKos_SP, and vKos_LP). The properties of these mutant viruses, in comparison to those of vKos_SL, were determined in pigs. Each of the viruses was virulent and induced typical clinical signs of CSF, but the vKos_LP strain produced them significantly earlier. Full-length CSFV cDNA amplicons (12.3 kb) derived from sera of infected pigs were deep sequenced and cloned to reveal the individual haplotypes that contributed to the single-nucleotide polymorphism (SNP) profiles observed in the virus population. The SNP profiles for vKos_SL and vKos_LL displayed low-level heterogeneity across the entire genome, whereas vKos_SP and vKos_LP displayed limited diversity with a few high-frequency SNPs. This indicated that vKos_SL and vKos_LL exhibited a higher level of fitness in the host and more stability at the consensus level, whereas several consensus changes were observed in the vKos_SP and vKos_LP sequences, pointing to adaptation. For each virus, only a subset of the variants present within the virus inoculums were maintained in the infected pigs. No clear tissue-dependent quasispecies differentiation occurred within inoculated pigs; however, clear evidence for transmission bottlenecks to contact animals was observed, with subsequent loss of sequence diversity. IMPORTANCE The surface-exposed E2 protein of classical swine fever virus is required for its interaction with host cells. A short motif within this protein varies between strains of different virulence. The importance of two particular amino acid residues in determining the properties of a highly virulent strain of the virus has been analyzed. Each of the different viruses tested proved highly virulent, but one of them produced earlier, but not more severe, disease. By analyzing the virus genomes present within infected pigs, it was found that the viruses which replicated within inoculated animals were only a subset of those within the virus inoculum. Furthermore, following contact transmission, it was shown that a very restricted set of viruses had transferred between animals. There were no significant differences in the virus populations present in various tissues of the infected animals. These results indicate mechanisms of virus population change during transmission between animals.

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STUDIES ON IMMUNITY TO PNEUMOCOCCUS MUCOSUS (TYPE III)

Journal of Experimental Medicine ◽

10.1084/jem.45.6.1093 ◽

1927 ◽

Vol 45 (6) ◽

pp. 1093-1106 ◽

Cited By ~ 2

Author(s):

William S. Tillett

Keyword(s):

Biological Property ◽

Infected Animal ◽

Virulent Strain ◽

The Other ◽

Natural Resistance ◽

Type Iii ◽

Mechanism Of Resistance ◽

Initial Decrease ◽

High Degree ◽

Highly Virulent

The observations recorded in this paper on the infectivity of Type III pneumococci for rabbits may be summarized as follows: 1. Of eleven strains of Type III isolated from human sources, ten were found to possess low virulence for rabbits. This was true despite the fact that all the strains tested possessed large capsules and a high degree of virulence for mice. 2. One strain of Type III pneumococcus was rendered highly virulent for rabbits. Since it possessed no other biological property demonstrably different from the other strains, its virulence must reside in some additional property. 3. An initial decrease in the number of circulating organisms following the injection of virulent bacteria is a well known occurrence, and it was observed in rabbits injected with the rabbit virulent strain of Type III. However, the extent of the reduction was in inverse proportion to the degree of virulence of the strain; a fact which makes mechanical explanations of the phenomenon insufficient. 4. The bacteremia produced in rabbits by Type III pneumococci, avirulent for this species, runs a characteristic course. It differs from that produced by non-encapsulated R forms of pneumococci although in both instances survival of the infected animal ensues. This is evidence that the mechanism of resistance against encapsulated and non-encapsulated pneumococci is not identical. 5. Phagocytosis of Type III pneumococci by circulating rabbit leucocytes was not demonstrable by a vital stain technique, whereas under the same conditions the ingestion of non-encapsulated R forms occurred. This is further evidence that the process whereby non-encapsulated pneumococci are disposed of, is insufficient to explain the natural resistance of rabbits to infection with encapsulated Type III pneumococci.

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Gut–Liver Immune Response and Gut Microbiota Profiling Reveal the Pathogenic Mechanisms of Vibrio harveyi in Pearl Gentian Grouper (Epinephelus lanceolatus♂ × E. fuscoguttatus♀)

Frontiers in Immunology ◽

10.3389/fimmu.2020.607754 ◽

2020 ◽

Vol 11 ◽

Author(s):

Yiqin Deng ◽

Yaqiu Zhang ◽

Haoxiang Chen ◽

Liwen Xu ◽

Qian Wang ◽

...

Keyword(s):

Immune Response ◽

Bacterial Community ◽

Gut Microbiota ◽

Vibrio Harveyi ◽

Virulent Strain ◽

Interspecies Interactions ◽

Genes Encoding ◽

Genetic Information Processing ◽

Cellular Immune ◽

Highly Virulent

Vibrio harveyi causes vibriosis in nearly 70% of grouper (Epinephelus sp.), seriously limiting grouper culture. As well as directly inhibiting pathogens, the gut microbiota plays critical roles in immune homeostasis and provides essential health benefits to its host. However, there is still little information about the variations in the immune response to V. harveyi infection and the gut microbiota of grouper. To understand the virulence mechanism of V. harveyi in the pearl gentian grouper, we investigated the variations in the pathological changes, immune responses, and gut bacterial communities of pearl gentian grouper after exposure to differently virulent V. harveyi strains. Obvious histopathological changes were detected in heart, kidney, and liver. In particular, nodules appeared and huge numbers of V. harveyi cells colonized the liver at 12 h postinfection (hpi) with highly virulent V. harveyi. Although no V. harveyi was detected in the gut, the infection simultaneously induced a gut-liver immune response. In particular, the expression of 8 genes associated with cellular immune processes, including genes encoding inflammatory cytokines and receptors, and pattern recognition proteins, was markedly induced by V. harveyi infection, especially with the highly virulent V. harveyi strain. V. harveyi infection also induced significant changes in gut bacterial community, in which Vibrio and Photobacterium increased but Bradyrhizobium, Lactobacillus, Blautia, and Faecalibaculum decreased in the group infected with the highly virulent strain, with accounting for 82.01% dissimilarity. Correspondingly, four bacterial functions related to bacterial pathogenesis were increased by infection with highly virulent V. harveyi, whereas functions involving metabolism and genetic information processing were reduced. These findings indicate that V. harveyi colonizes the liver and induces a gut-liver immune response that substantially disrupts the composition of and interspecies interactions in the bacterial community in fish gut, thereby altering the gut-microbiota-mediated functions and inducing fish death.

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Draft Genome Sequence of a Rare Israeli Clinical Isolate of Burkholderia pseudomallei

Microbiology Resource Announcements ◽

10.1128/mra.00281-19 ◽

2019 ◽

Vol 8 (19) ◽

Cited By ~ 1

Author(s):

Ofir Israeli ◽

Inbar Cohen-Gihon ◽

Tal Brosh-Nissimov ◽

Shay Weiss ◽

Anat Zvi ◽

...

Keyword(s):

Clinical Isolate ◽

Genome Sequence ◽

Burkholderia Pseudomallei ◽

Virulent Strain ◽

Draft Genome ◽

Draft Genome Sequence ◽

Content Type ◽

Highly Virulent

We report here the draft genome sequence of Burkholderia pseudomallei MAA2018. This highly virulent strain was isolated in 2018 from the first melioidosis case in Israel associated with recreational travel to Goa, India.

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Clinical Course and Gross Pathological Findings in Wild Boar Infected with a Highly Virulent Strain of African Swine Fever Virus Genotype II

Pathogens ◽

10.3390/pathogens9090688 ◽

2020 ◽

Vol 9 (9) ◽

pp. 688 ◽

Cited By ~ 1

Author(s):

Antonio Rodríguez-Bertos ◽

Estefanía Cadenas-Fernández ◽

Agustín Rebollada-Merino ◽

Néstor Porras-González ◽

Francisco J. Mayoral-Alegre ◽

...

Keyword(s):

Wild Boar ◽

Clinical Course ◽

African Swine Fever Virus ◽

Virulent Strain ◽

African Swine Fever ◽

Pathological Findings ◽

Wild Boars ◽

Gross Pathology ◽

Highly Virulent ◽

Genotype Ii

African swine fever (ASF) is a notifiable disease that in recent years has spread remarkably in Europe and Asia. Eurasian wild boar (Sus scrofa) plays a key role in the maintenance and spread of the pathogen. Here we examined gross pathology of infection in wild boar with a highly virulent, hemadsorbing genotype II ASF virus (ASFV) strain. To this end, six wild boars were intramuscularly inoculated with the 10 HAD50 Arm07 ASFV strain, and 11 wild boars were allowed to come into direct contact with the inoculated animals. No animals survived the infection. Clinical course, gross pathological findings and viral genome quantification by PCR in tissues did not differ between intramuscularly inoculated or contact-infected animals. Postmortem analysis showed enlargement of liver and spleen; serosanguinous effusion in body cavities; and multiple hemorrhages in lungs, endocardium, brain, kidneys, urinary bladder, pancreas, and alimentary system. These results provide detailed insights into the gross pathology of wild boar infected with a highly virulent genotype II ASFV strain. From a didactic point of view, this detailed clinical course and macroscopic description may be essential for early postmortem detection of outbreaks in wild boar in the field and contribute to disease surveillance and prevention efforts.

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Draft Genome Sequence of Streptococcus suis S10, a Virulent Strain Used in Experimental Pig Infections

Microbiology Resource Announcements ◽

10.1128/mra.00227-19 ◽

2019 ◽

Vol 8 (23) ◽

Author(s):

Rogier A. Gaiser ◽

Aldert L. Zomer ◽

Jerry M. Wells ◽

Peter van Baarlen

Keyword(s):

Infectious Diseases ◽

Genome Sequence ◽

Virulent Strain ◽

Draft Genome ◽

Streptococcus Suis ◽

Draft Genome Sequence ◽

Whole Genome Sequence ◽

Whole Genome ◽

Content Type ◽

Highly Virulent

Here, we report the draft whole-genome sequence of Streptococcus suis strain S10, isolated from the tonsils of a healthy pig. S. suis S10 belongs to the highly virulent serotype 2, which includes isolates that cause infectious diseases, including meningitis, in pigs and human.

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