Plague Research Today is a free monthly online journal that collates and summarizes the latest research about Plague, including details on bubonic plague, yersinia pestis, infection, types, treatment.

Flea abundance on black-tailed prairie dogs (Cynomys ludovicianus) increases during plague epizootics.

Tripp DW, Gage KL, Montenieri JA, Antolin MF

Department of Biology and Shortgrass Steppe Long-Term Ecological Project, Colorado State University, Fort Collins, Colorado 80523, USA.

Black-tailed prairie dogs (Cynomys ludovicianus) on the Great Plains of the United States are highly susceptible to plague, caused by the bacterium Yersinia pestis, with mortality on towns during plague epizootics often approaching 100%. The ability of flea-borne transmission to sustain disease spread has been questioned because of inefficiency of flea vectors. However, even with low individual efficiency, overall transmission can be increased if flea abundance (the number of fleas on hosts) increases. Changes in flea abundance on hosts during plague outbreaks were recorded during a large-scale study of plague outbreaks in prairie dogs in north central Colorado during 3 years (2004-2007). Fleas were collected from live-trapped black-tailed prairie dogs before and during plague epizootics and tested by PCR for the presence of Y. pestis. The predominant fleas were two prairie dog specialists (Oropsylla hirsuta and Oropsylla tuberculata cynomuris), and a generalist flea species (Pulex simulans) was also recorded from numerous mammals in the area. The three species differ in seasonal abundance, with greatest abundance in spring (February and March) and fall (September and October). Flea abundance and infestation intensity increased during epizootics and were highest on prairie dogs with Y. pestis-infected fleas. Seasonal occurrence of epizootics among black-tailed prairie dogs was found to coincide with seasonal peaks in flea abundance. Concentration of infected fleas on surviving animals may account for rapid spread of plague during epizootics. In particular, the role of the generalist flea P. simulans was previously underappreciated.

Published 18 June 2009 in Vector Borne Zoonotic Dis, 9(3): 313-21.
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Articles on Plague published 16 June 2009:

Yersinia pestis endowed with increased cytotoxicity is avirulent in a bubonic plague model and induces rapid protection against pneumonic plague.   PLoS One, 4(6): e5938.

An important virulence strategy evolved by bacterial pathogens to overcome host defenses is the modulation of host cell death. Previous observations have indicated that Yersinia pestis, the causative agent of plague disease, exhibits restricted capacity to induce cell death in macrophages due to ineffective translocation of the type III secretion effector YopJ, as opposed to the readily translocated YopP, the YopJ homologue of the enteropathogen Yersinia enterocolitica Oratio8. This led us to ... [Abstract] [Full-text]

Articles on Plague published 15 June 2009:

Differential gene expression in black tiger shrimp, Penaeus monodon, following administration of oxytetracycline and oxolinic acid.   Dev Comp Immunol.

The intensification of shrimp farming systems has led to the spreading of a variety of bacterial and viral diseases that continue to plague the shrimp industry worldwide. Efforts to combat these pathogenic organisms include the use of immunostimulants, probiotics, vaccines and antibiotics. Although a few studies have already reported on the effects of various stimuli on shrimp, the effect of antibiotics, particularly on the changes in the shrimp transcriptomic profile have yet to be reported. ... [Abstract] [Full-text]

Articles on Plague published 12 June 2009:

Bench-to-bedside review: Appropriate antibiotic therapy in severe sepsis and septic shock - does the dose matter?   Crit Care, 13(3): 214.

ABSTRACT: Appropriate antibiotic therapy in patients with severe sepsis and septic shock should mean prompt achievement and maintenance of optimal exposure at the infection site with broad-spectrum antimicrobial agents administered in a timely manner. Once the causative pathogens have been identified and tested for in vitro susceptibility, subsequent de-escalation of antimicrobial therapy should be applied whenever feasible. The goal of appropriate antibiotic therapy must be pursued resolutely ... [Abstract] [Full-text]

Articles on Plague published 8 June 2009:

Development and evaluation of an antigen-capture ELISA for detection of the UL24 antigen of the duck enteritis virus, based on a polyclonal antibody against the UL24 expression protein.   J Virol Methods.

An antigen-capture enzyme-linked immunosorbent assay (AC-ELISA) method was developed for the efficient detection of the UL24 antigen of the duck enteritis virus (DEV) using polyclonal antibodies. Ducks and rabbits were immunized, respectively, with expressed UL24 recombinant protein. The IgG antibodies against UL24 from ducks and rabbits were purified and used as the capture antibodies. The specificity of the optimized AC-ELISA was evaluated by use of DEV, duck hepatitis virus (DHV), duck ... [Abstract] [Full-text]

Articles on Plague published 5 June 2009:

Expedited growth factor-mediated specification of human embryonic stem cells toward the hepatic lineage.   Stem Cell Res.

Human embryonic stem cells (hESCs) have the potential to be a promising source of liver cells, hepatocytes, for regenerative medicine given their unlimited proliferative and pluripotent differentiative capacity. However, the inefficient embryoid body process and limited understanding of molecular signals potentiating cell-specific differentiation plague the use of hESCs as a hepatic source. In this study, we describe an efficient growth factor-based process for directed differentiation of hESCs ... [Abstract] [Full-text]

Articles on Plague published 29 May 2009:

His6-Tagged UL35 Protein of Duck Plague Virus: Expression, Purification, and Production of Polyclonal Antibody.   Intervirology, 52(3): 141-151.

Objective: Duck plague virus (DPV), the causative agent of duck plague (DP), is an alphaherpesvirus that causes an acute, febrile, contagious, and septic disease of waterfowl. UL35 protein (VP26) is a major capsid protein encoded by the UL35 gene, which is located in the unique long (UL) region of the DPV genome. To investigate the specific roles of VP26, the UL35 gene was amplified from the DPV DNA by polymerase chain reaction (PCR) and subcloned into pET-32a(+). Methods: The resultant ... [Abstract] [Full-text]

Articles on Plague published 25 May 2009:

Isolation, Identification, and Characterization of Small Bioactive Peptides From Lactobacillus GG Conditional Media That Exert Both Anti-Gram-negative and Gram-positive Bactericidal Activity.   J Pediatr Gastroenterol Nutr.

OBJECTIVES:: Diarrheal diseases remain a major human plague that still claim millions of lives every year. Probiotics, including Lactobacillus GG (LGG), are known to have a beneficial effect on diarrheal diseases, but their mechanism of action has not yet been completely established. Therefore, the main objective of this work was to identify and characterize moieties elaborated by LGG that exert antibacterial activity. MATERIALS AND METHODS:: Lactobacillus GG conditional media was subjected to ... [Abstract] [Full-text]

The single substitution I259T conserved in the plasminogen activator Pla of pandemic Yersinia pestis branches enhances fibrinolytic activity.   J Bacteriol.

The outer-membrane plasminogen activator Pla of Yersinia pestis is a central virulence factor in plague. The primary structure of the Pla beta-barrel is conserved in Y. pestis biovars Antiqua, Medievalis, and Orientalis associated with pandemics of plague. The Pla molecule of the ancestral Y. pestis lineages Microtus and Angola carries the single amino acid change T259I located in the surface loop 5 of the beta-barrel. Recombinant Y. pestis KIM D34 or Escherichia coli XL1 expressing Pla T259I ... [Abstract] [Full-text]

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