Host resistance and parasite virulence are influenced by multiple interacting factors in complex natural communities. Yet, these interactive effects are seldom studied concurrently, resulting in poor understanding of host-pathogen-environment dynamics. Here, we investigated how the level of opportunist pathogen virulence, strength of host immunity and the host condition manipulated via diet aff...

Many enteric pathogens are thought to enter a viable but nonculturable state when deprived of nutrients. Virulent strains of the enteric pathogen Vibrio parahaemolyticus are rarely isolated from their low-nutrient aquatic environments, possibly due to their nonculturability. Host factors such as bile may trigger release from dormancy and increase virulence in these strains. In this study, the a...

Several tissue culture lines of 6C3HED, a murine lymphoma, were more susceptible to immunologic destruction in vivo than the highly virulent 6C3HED line maintained by serial intramuscular transplantation. The attenuated tissue culture cells were rejected by normal syngeneic recipients, but thymectomized mice were unable to reject attenuated cells. In such mice, the growth rate of attenuated cel...

the virulence of pasteurella multocida (p. multocida) serotype a1 for chickens and mice was determined. groups of chicken and mice were exposed intramuscularly and intraperitoneally to various concentration of p. multocida broth culture, respectively. this strain was highly virulent for chickens so that those exposed to only 7 c.f.u. of the organism died in less than 24 hours. groups of mice ex...

Dendritic cells (DCs) constitute the link between innate and adaptive immunity by directly recognizing pathogen-associated molecular patterns (PAMPs) in bacteria and by presenting bacterial antigens to T cells. Recognition of PAMPs renders DCs as professional antigen-presenting cells able to prime naïve T cells and initiate adaptive immunity against bacteria. Therefore, interfering with DC func...

BACKGROUND: Colibacillosis is one of the most prevalentdiseases in the world that causes multimillion-dollar annuallosses. OBJECTIVES: In order to evaluate molecular epidemiologyof some virulence associated factors in Escherichia coli,isolated from poultry, the presence of iut A, iss, hly F, omp T, iroN, afa, sfa (S)and pap G (II) were investigated by multiplex PCRassay. METHODS: Two hundred th...

Streptococcus suis serotype 2 is an important porcine bacterial pathogen and emerging zoonotic agent mainly responsible for sudden death, septic shock, and meningitis, with exacerbated inflammation being a hallmark of the infection. However, serotype 2 strains are genotypically and phenotypically heterogeneous, being composed of a multitude of sequence types (STs) whose virulence greatly varies...

Xanthomonas arboricola is a plant-associated bacterial species that causes diseases on several plant hosts. One of the most virulent pathovars within this species is X. arboricola pv. pruni (Xap), the causal agent of bacterial spot disease of stone fruit trees and almond. Recently, a non-virulent Xap-look-a-like strain isolated from Prunus was characterized and its genome compared to pathogenic...

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 wer...