Avian pathogenic Escherichia coli (APEC) is an economically important respiratory pathogen of chickens worldwide. Factors previously associated with the virulence of APEC include adhesins, iron-scavenging mechanisms, the production of colicin V (ColV), serum resistance, and temperature-sensitive hemagglutination, but virulence has generally been assessed by parenteral inoculation, which does no...

in this study, twenty-five strains of mycobacterium tuberculosis resistant to isoniazid (inh) were isolated from patients with tuberculosis (tb). nine strains (36%) were found to be virulent in guinea-pigs [root index virulence (riv» 1 ]. the remaining sixteen strains (64%) were non-virulent (riv <1). of the nine strains resistant to inh as well as virulent to guinea-pigs, eight of them were fo...

the dry bubble disease, caused by lecanicillium fungicola, is an important fungal disease of white button mushroom in iranian mushroom production farms. twenty-three isolates of the pathogen collected in iran and identified as l. fungicola var. fungicola, were compared for genetic polymorphism, diversity in growth rate and virulence. ten universal rice primers (urp) were used to evaluate the ge...

The vast majority of infections involving female pelvic structures arise from organisms that are members of the normal flora. In addition, exogenous organisms that invade through the lower genital tract must interact with organisms that are part of the host's flora. In contrast to the concept that the normal flora is entirely innocuous, recent research has begun to identify what appear to be vi...

Most models of virulence evolution assume that transmission and virulence are constant during an infection. In many viral (HIV and influenza), bacterial (TB) and prion (BSE and CWD) systems, disease-induced mortality occurs long after the host becomes infectious. Therefore, we constructed a model with two infected classes that differ in transmission rate and virulence in order to understand how...

Evolutionary models predict that parasite virulence (parasite-induced host mortality) can evolve as a consequence of natural selection operating on between-host parasite transmission. Two major assumptions are that virulence and transmission are genetically related and that the relative virulence and transmission of parasite genotypes remain similar across host genotypes. We conducted a cross-i...

Avian pathogenic Escherichia coli (APEC) is an important respiratory pathogen of poultry. Various virulence factors are responsible for determining the pathogenicity of these strains, and it is commonly believed they are encoded on large plasmids the strains carry. This study examined a series of strains, the pathogenicity of which had previously been determined by aerosol exposure, for possess...

Herpes simplex virus type 1 latency-associated transcript (LAT)-null mutants have decreased reactivation but normal virulence in rabbits and mice. We report here on dLAT1.5, a mutant with LAT nucleotides 76 to 1667 deleted. Following ocular infection of rabbits, dLAT1.5 reactivated at a lower rate than its wild-type parent McKrae (6.1 versus 11.8%; P = 0.0025 [chi-square test]). Reactivation wa...

conclusions our results show the presence of clonal groups of enterotoxin-producing mrsa strains in this hospital in tehran. the presence of bacteriophage encoded virulence factors and resistance to oxacillin enable bacteria to produce a broad spectrum range of diseases. results out of the 279 s. aureus isolates, 91 (32.6%) strains were confirmed as mrsa. totally, 6 enterotoxin and 2 virulence ...

A study was conducted to determine the pathogens causing root rot, wilt and dieback disease of Cinnamomum cassia (Chinese cinnamon or cassia) in Vietnam, nurseries plantations Yen Bai, Quang Ninh, Thanh Hoa Nam provinces, streams Bai province. Pathogens were identified using morphology internal transcribed spacer (ITS) sequence analysis. The 204 isolates obtained included 125 Phytophthora 79 fr...