Transmission of mycoviruses that attenuate virulence (hypovirulence) of pathogenic fungi is restricted by allorecognition systems operating in their fungal hosts. We report the use of systematic molecular gene disruption and classical genetics for engineering fungal hosts with superior virus transmission capabilities. Four of five diallelic virus-restricting allorecognition [vegetative incompat...

Plants and animals possess innate immune systems to prevent infections and are effectively "nonhosts" for most potential pathogens. The molecular mechanisms underlying nonhost immunity in plants remain obscure. In Arabidopsis, nonhost/nonpathogenic Pseudomonas syringae sustains but pathogenic P. syringae suppresses early MAMP (microbe-associated molecular pattern) marker-gene activation. We per...

Virulence factor genes encoding the thermostable direct hemolysin (tdh) and the thermostable direct hemolysin-related hemolysin (trh) are strongly correlated with virulence of the emergent human pathogen Vibrio parahaemolyticus. The gene encoding the thermolabile hemolysin (tlh) is also considered a signature molecular marker for the species. These genes are typically reported in very low perce...

Among 75 urosepsis isolates of Escherichia coli, 29 virulence factor (VF) genes were detected by use of a novel polymerase chain reaction (PCR) assay. Compared with probe hybridization, the PCR assay's specificity was 100% and sensitivity 97.1%. fyuA (yersiniabactin: overall prevalence, 93%), traT (serum resistance, 68%), and a pathogenicity-associated island marker (71%) occurred in most strai...

Immune sera were produced in rabbits with living cells of an enteroinvasive O143 strain of Escherichia coli. To remove O and K antibodies, sera were absorbed with an avirulent derivative of the same strain. In the enzyme-linked immunosorbent assay, absorbed sera reacted specifically with only virulent Shigella strains and enteroinvasive E. coli strains of different geographical origin, regardle...

We have mutagenized and mapped the gene encoding the large subunit of ribonucleotide reductase (RR1) in pseudorabies virus (PRV; synonyms Aujeszky's disease virus, suid herpesvirus type 1). PRV strains carrying an oligonucleotide that leads to termination of translation of the RR1 gene are avirulent for mice. We subsequently constructed a PRV strain carrying a deletion in the RR1 gene and also ...

Over the past two decades, an epidemiologic emergence of methicillin-resistant Staphylococcus aureus (MRSA) infections has occurred from that of primarily hospital-associated to community-associated. This emergence change has involved MRSA of different pulsed-field types (PFT), with different virulence genes and antimicrobial resistance patterns. In this study we, evaluate the changes in PFT an...

Serum resistance is an important virulence marker in uropathogenic E. coli (UPEC) but its pattern with respect to commensal gastrointestinal strains is less studied. We compared the serum resistance pattern of UPEC with commensal strains in stool samples from healthy individuals. A total of 40 isolates of UPEC (test) and intestinal E. coli (control) each was obtained from patients of all age gr...

Agrobacterium tumefaciens can cause crown gall tumors on a wide range of host plants. As a natural genetic engineer, the bacterium can transfer both single-stranded DNA (ssDNA) [transferred DNA (T-DNA)] molecules and bacterial virulence proteins into various recipient cells. Among Agrobacterium-delivered proteins, VirE2 is an ssDNA binding protein that is involved in various steps of the transf...

Background: The virulence of a pathogenic Vibrio cholerae is dependent on a discrete set of genetic determinants. In this study, we determined the distribution of virulence determinants among the clinical and environmental isolates of V. cholerae. Methods: The antibiotic resistance profiles of the isolates were determined using standard disk diffusion assay. PCR assay was performed to analyze t...