Nucleotide sequences were determined for two hop stunt viroid-related Group II citrus viroids characterized as either a cachexia disease non-pathogenic variant (CVd-IIa) or a pathogenic variant (CVd-IIb). Sequence identity between the two variants of 95.6% indicated a conserved genome with the principal region of nucleotide difference clustered in the variable (V) domain. Full-length viroid RT-...

conclusions expression levels of 1,426 genes were significantly up-regulated in the mutant compared to wt. furthermore, 301 genes were down-regulated with false discovery rates (fdr) of < 0.001 and absolute value of log2 ratio of ≥ 1. results a total of 4,182,944 and 4,182,021 clean tags were obtained from the wt and a nonpathogenic mutant stain (bct89), respectively, and 10,410 differentially ...

newcastle disease virus (ndv) was isolated and identified for the first time from a flock of japanese quail suspected to nd in iran. birds of the flock aged variously, and some of them died from the disease. loss of appetite, weakness and decrease in egg production, diarrhea and nervous symptoms were the main clinical signs in the birds. hemorrhagic lesions of the intestinal tracts and proventr...

the pathogenicity of a recent isolate of infectious bursal disease virus (ibdv), ir499, isolated from a nonvaccinated flock with 17.5 % mortality rate in susceptible spf chickens, chickens embryos and broilers was discussed. the molecular characterization of the virus based on the restriction fragment length polymorphism (rflp) pattern was also investigated. the mortality rates were 85% and 22%...

Under the gene-for-gene model of host-pathogen coevolution, recognition of pathogen avirulence factors by host resistance factors triggers host defenses and limits infection. Theory predicts that the evolution of higher levels of pathogenicity will be associated with fitness penalties and that the cost of higher pathogenicity must be much smaller than that of not infecting the host. The analysi...

H5N1 highly pathogenic avian influenza virus (HPAIV) of clade 2.3.2 has been circulating in waterfowl in Southern China since 2003. Our previous studies showed that certain H5N1 HPAIV isolates within clade 2.3.2 from Southern China had high pathogenicity in different birds. Guinea pigs have been successfully used as models to evaluate the transmissibility of AIVs and other species of influenza ...

Background: Diarrheagenic Escherichia coli (DEC) strains are a major cause of diarrhea in children under 5 years of age worldwide. DEC pathogenicity relies on the interaction of bacteria with environmental factors, including the host's resident gut microbiota. Previous reports have shown changes in the gut microbiota's composition during episodes of diarrhea, which may increase the pathogenicit...

We compared a previously characterized herpes simplex type 1 alpha 0 deletion mutant, dlx3.1, which produced no functional ICP0, with its wild-type parental strain, KOS, during acute ocular infection of different host animals. Acute pathogenicity of the viral strains in NZ rabbits, Balb/c and A/J mice was evaluated by keratitis scores, ocular and trigeminal ganglionic viral titers, and host sur...

The adaptability of pathogenic bacteria to hosts is influenced by the genomic plasticity of the bacteria, which can be increased by such mechanisms as horizontal gene transfer. Pathogenicity islands play a major role in this type of gene transfer because they are large, horizontally acquired regions that harbor clusters of virulence genes that mediate the adhesion, colonization, invasion, immun...

Virulence factors of pathogenic bacteria (adhesins, toxins, invasins, protein secretion systems, iron uptake systems, and others) may be encoded by particular regions of the prokaryotic genome termed pathogenicity islands. Pathogenicity islands were first described in human pathogens of the species Escherichia coli, but have recently been found in the genomes of various pathogens of humans, ani...