Computational Reverse-Engineering of a Spider-Venom Derived Peptide Active Against Plasmodium falciparum SUB1

merozoites and invasion into erythrocytes. As PfSUB1 has emerged as an interesting drug target, we explored the hypothesis that PcFK1 targeted PfSUB1 enzymatic activity. culture in a range compatible with our bioinformatics analysis. Using contact analysis and free energy decomposition we propose that residues A14 and Q15 are important in the interaction with PfSUB1.Our computational reverse engineering supported the hypothesis that PcFK1 targeted PfSUB1, and this was confirmed by experimental evidence showing that PcFK1 inhibits PfSUB1 enzymatic activity. This outlines the usefulness of advanced bioinformatics tools to predict the function of a protein structure. The structural features of PcFK1 represent an interesting protein scaffold for future protein engineering

L'infection genitale par les herpes simplex virus parmi des hommes consultant pour un depistage des papillomavirus genitaux

OBJECTIVE. Our aim was to assess the frequency of herpetic genital infection (HSV) among men attending a human papillomavirus (HPV) screening centre. Clinical screening of a herpetic lesion was completed with biological detection of HSV by cell culture and by polymerase chain reaction (PCR). We also evaluated the role of the male viral factor on the female partners. METHOD. We performed a genital examination by colposcopy of 135 men whose female partners presented an HPV genital infection. The HPV lesions detected underwent biopsy by Southern blot viral analysis. The lesions which clinically appeared to be caused by HSV were removed for HSV detection and typing by cell culture and by PCR. Sperm was collected for viral detection by cell culture and PCR was collected for viral detection by cell culture and PCR from patients presenting a herpetic type urethral symptomatology. RESULTS. Peniscopy detected HPV lesions in 46 p. 100 of the men, in 88 p. 100 of cases in the balano-preputial zone and in 82 p. 100 of cases their morphology was exophytic. The other areas were in 14.5 p. 100 of cases urethral and 9 p. 100 anal. We detected a dysplasic lesion in 6 p. 100 of cases. In 74 p. 100 of cases molecular hybridization by Southern detected 6/11/42 type HPV and in 6.4 p. 100 of cases HPV 16. Clinical examination revealed the presence of genital herpetic infection in 15.5 p. 100 of cases, of these 76 p. 100 were preputial and 24 p. 100 meato-urethral. PCR detected HSV-2 in 88 p. 100 of the preputial lesions and in 86 p. 100 of the spermatic ejaculates from the meato-urethral lesions. The chi 2 test showed that no link exists between a herpetic genital infection and the presence of an HPV lesion, but that the risk is greater (OR = 2.15; IC 95 p. 100 = 0.84-5.49). We also observed that 50 p. 100 of the female partners of men with both HPV+HSV infections had high grade cervical lesions. CONCLUSION. This study shows that clinical examination in an HPV screening centre enabled detection of clinical HSV in 15.5 p. 100 of cases as opposed to 17 p. 100 biologically. Thus the good clinical-virological correlation shows that clinical criteria remain the principal elements for detecting viral genital infections, it therefore appears advantageous to only use the new HSV identification techniques for targeted detection. Also, herpetic genital infection is independent of human papillomavirus infection. When screening for HPV, herpetic genital infection should be taken into account as we have observed that the female partners of men with both HPV + HSV are at greater risk of presenting high grade cervical lesions

Susceptibility to Experimental Cerebral Malaria Induced by Plasmodium berghei ANKA in Inbred Mouse Strains Recently Derived from Wild Stock

The neurological syndrome caused by Plasmodium berghei ANKA in rodents partially mimics the human disease. Several rodent models of cerebral malaria (CM) exist for the study of the mechanisms that cause the disease. However, since common laboratory mouse strains have limited gene pools, the role of their phenotypic variations causing CM is restricted. This constitutes an obstacle for efficient genetic analysis relating to the pathogenesis of malaria. Most common laboratory mouse strains are susceptible to CM, and the same major histocompatibility complex (MHC) haplotype may exhibit different levels of susceptibility. We analyzed the influence of the MHC haplotype on overcoming CM by using MHC congenic mice with C57BL/10 and C3H backgrounds. No correlation was found between MHC molecules and the development of CM. New wild-derived mouse strains with wide genetic polymorphisms were then used to find new models of resistance to CM. Six of the twelve strains tested were resistant to CM. For two of them, F(1) progeny and backcrosses performed with the reference strain C57BL/6 showed a high level of heterogeneity in the number and characteristics of the genetic factors associated with resistance to CM

Tetanus Toxin Synthesis is Under the Control of A Complex Network of Regulatory Genes in Clostridium tetani

International audienceClostridium tetani produces a potent neurotoxin, the tetanus toxin (TeNT), which is responsible for an often-fatal neurological disease (tetanus) characterized by spastic paralysis. Prevention is efficiently acquired by vaccination with the TeNT toxoid, which is obtained by C. tetani fermentation and subsequent purification and chemical inactivation. C. tetani synthesizes TeNT in a regulated manner. Indeed, the TeNT gene (tent) is mainly expressed in the late exponential and early stationary growth phases. The gene tetR (tetanus regulatory gene), located immediately upstream of tent, encodes an alternative sigma factor which was previously identified as a positive regulator of tent. In addition, the genome of C. tetani encodes more than 127 putative regulators, including 30 two-component systems (TCSs). Here, we investigated the impact of 12 regulators on TeNT synthesis which were selected based on their homology with related regulatory elements involved in toxin production in other clostridial species. Among nine TCSs tested, three of them impact TeNT production, including two positive regulators that indirectly stimulate tent and tetR transcription. One negative regulator was identified that interacts with both tent and tetR promoters. Two other TCSs showed a moderate effect: one binds to the tent promoter and weakly increases the extracellular TeNT level, and another one has a weak inverse effect. In addition, CodY (control of dciA (decoyinine induced operon) Y) but not Spo0A (sporulation stage 0) or the DNA repair protein Mfd (mutation frequency decline) positively controls TeNT synthesis by interacting with the tent promoter. Moreover, we found that inorganic phosphate and carbonate are among the environmental factors that control TeNT production. Our data show that TeNT synthesis is under the control of a complex network of regulators that are largely distinct from those involved in the control of toxin production in Clostridium botulinum or Clostridium difficile

Reduced artemisinin susceptibility of Plasmodium falciparum ring stages in western Cambodia.

The declining efficacy of artemisinin derivatives against Plasmodium falciparum in western Cambodia is a major concern. The knowledge gap in the understanding of the mechanisms involved hampers designing monitoring tools. Here, we culture-adapted 20 isolates from Pailin and Ratanakiri (areas of artemisinin resistance and susceptibility in western and eastern Cambodia, respectively) and studied their in vitro response to dihydroartemisinin. No significant difference between the two sets of isolates was observed in the classical isotopic test. However, a 6-h pulse exposure to 700 nM dihydroartemisinin (ring-stage survival assay -RSA]) revealed a clear-cut geographic dichotomy. The survival rate of exposed ring-stage parasites (ring stages) was 17-fold higher in isolates from Pailin (median, 13.5%) than in those from Ratanakiri (median, 0.8%), while exposed mature stages were equally and highly susceptible (0.6% and 0.7%, respectively). Ring stages survived drug exposure by cell cycle arrest and resumed growth upon drug withdrawal. The reduced susceptibility to artemisinin in Pailin appears to be associated with an altered in vitro phenotype of ring stages from Pailin in the RSA