Aromatic compound-dependent (aro) derivatives of three mouse-virulent strains of Salmonella choleraesuis (Salmonella cholerae-suis) were constructed and shown to be nonvirulent for mice (intraperitoneal [i.p.] 50% lethal dose [LD50], greater than 5 X 10(6) CFU). A pur derivative, and a thy derivative, each of a different virulent parent, remained moderately virulent (i.p. LD50S for BALB/c mice,...

Brubaker, Robert R. (Fort Detrick, Frederick, Md.) and Michael J. Surgalla. Genotypic alterations associated with avirulence in streptomycin-resistant Pasteurella pestis. J. Bacteriol. 84:615-624. 1962.-Avirulence in Pasteurella pestis, as indicated by the existence of a new genotype, was associated with the genetic loss of Ca(++) dependence rather than with the usual concomitant loss of abilit...

Abstract: This study was conducted to characterize infectious bursal disease virus (IBDV) isolates collected from different parts of Iran during 2005-2006. Pooled bursal samples from 49 broiler and layer pullet flocks suspected to IBD infection were collected and processed. A reverse transcriptase-polymerase chain reaction (RT PCR) procedure was used to amplify a VP2 gene fragment (743 bp) from...

We use spatial and non spatial models to argue that competition alone may explain why two influenza strains do not usually coexist during a given flu season. The more virulent strain is likely to crowd out the less virulent one. This can be seen as a consequence of the Exclusion Principle of Ecology. We exhibit, however, a spatial model for which coexistence is possible.

The dynamics of in-host infections are central to predicting the progression of natural infections and the effectiveness of drugs or vaccines, however, they are not well understood. Here, we apply food web theory to in-host disease networks of the human body that are structured similarly to food web models that treat both predation and competition simultaneously. We show that in-host trade-offs...

The surface proteins of several Bordetella strains and their modulated derivatives were examined by surface radioiodination, cell fractionation, and Western blotting. A surface protein with a high Mr, missing in a mutant lacking the filamentous hemagglutinin, was identified in virulent Bordetella pertussis and Bordetella parapertussis cells and was absent in avirulent B. pertussis strains. The ...

Infectious bursal disease (IBD) is a highly contagious disease of chickens caused by the infectious bursal disease virus (IBDV). This study was conducted to characterize three IBDV strains from Iran. A reverse transcriptase-polymerase chain reaction (RT-PCR) procedure was used to amplify a 715-bp fragment of the VP1 gene from IBDV strains. Amplified VP1 fragments of the three Iranian IBDV strai...

Introduction Cutaneous anthrax is endemic in Georgia1. The EIDSS program captures notifications from 72 municipal public health centers. It links urgent notification, case investigation data, and laboratory data on an online basis. Eleven virulent and 4 non-virulent strains of B. anthracis have been isolated. Genotype GK 35 and GK 44 are strains found in the Turkish-Southern Caucasian region. I...

Transmission and scanning electron microscopy were used to study the phagocytosis of virulent and avirulent strains of Legionella pneumophila. The interaction between L. pneumophila and peritoneal macrophages from normal guinea pigs or from animals that had survived infection was studied. The virulent strains survived and proliferated within the phagocyte after ingestion by either type of macro...

We use spatial and non spatial models to argue that competition alone may explain why two influenza strains do not usually coexist. The more virulent strain is likely to crowd out the less virulent one. This can be seen as a consequence of the Exclusion Principle of Ecology. We exhibit, however, a spatial model for which coexistence is possible.