[Ecology of Glossina palpalis VANDERPLANK, 1949 (Diptera: Glossinidae) in mangrove area of Guinea: influence of tides on tsetse densities]

The mangrove area on the Guinea littoral constitutes a favourable habitat for transmission of Trypanosoma brucei gambiens, the parasite causing sleeping sickness also called Human African Trypanosmosis (HAT), due the simultaneous presence of the vector (tsetse flies) and the human hosts. In order to assess the influence of the sea tides on the densities of Glossina palpalis gambiensis (Gpg), major vector of HAT in the mangrove, entomological surveys were performed using two transects, according to tides coefficient (great and small) and tide daily fluctuations (high and low). On each transect, 12 biconical traps were deployed through the mangrove to the continent. In total, up to 612 Gpg were caught, giving a density of 2.13 flies/trap/day (f/t/d). Highest captures were recorded during small tides and more tsetse were caught during the dry season than in the wet season. There were significant differences between captures when considering the different biotopes, and highest tsetse densities were recorded at the junction of the river and the channel of the mangrove (6.17±5.24); and in the channels of mangrove (3.50±3.76), during high tides of small coefficients. The results of this study may be used to improve vector control methods.

Influence of host origin on host choice of the parasitoid Dinarmus basalis: does upbringing influence choices later in life?

The aim of this study was to investigate the influence of volatile compounds from four secondary host plants on the ability of Dinarmus basalis Rond. (Hymenoptera: Pteromalidae) to locate, recognize, and parasitize its host, 4(th)instar larvae or pupae of Callosobruchus maculatus F. (Coleoptera: Chrysomelidae). To examine this, strains of D. basalis were transferred from cow-pea seeds (Vigna unguiculata (L.) Walp. (Fabales: Fabaceae)) to pigeon pea (Cajanus cajan (L.) Millsp.) and two varieties of Bambara groundnut (Vigna subterranea (L.) Verdc.) seeds. The ability of D. basalis females to recognize the volatile compounds emanating from their complex host plant was tested by using a Y-tube olfactometer and a three-dimensional device. The results suggest that when females have a choice between pure air and the air emanating from their complex host of origin, they are attracted to the air tainted by the volatile compounds they have become accustomed to. They spent significantly more time (p < 0.0001) in the branch of the tube leading to the odorous air than in the tube leading to the pure air. When females from pigeon pea seed hosts were offered a choice between cowpea and pigeon pea seeds, all containing 4(th)instar larvae, the familiar odor of pigeon pea seeds were most attractive. When females from Bambara groundnut (white and striped) seed hosts were offered a choice between cowpea and pigeon pea seeds, all containing 4(th)instar larvae, they were significantly attracted to the odour of cowpea seeds. In the three-dimensional system, the females from the four strains did not appear to have any preference for a given type of seed containing 4(th)instar larvae or pupae. The parasitism rate remained high on all four types of seeds used. These results show that the use of D. basalis as a biological control agent is possible in host changing situations where C. maculatus starts to attack other legumes. The results of this study also provide information supporting the behavioral plasticity of D. basalis. Understanding the mechanisms involved in the adaptive phenomena of biological control agents is discussed in the context of the development of adequate methods of pest control.

[Behavioral interactions and rhythms of activity of Glossina palpalis gambiensis and G. tachinoides (Diptera: Glossinidae) in a forest gallery in Burkina Faso]

Glossina palpalis gambiensis et G. tachinoides sont des vecteurs majeurs des trypanosomoses humaines et animales en Afrique de l’Ouest. Sur une partie de leur aire de répartition, elles sont présentes en sympatrie, mais très peu d’informations sont disponibles sur leurs interactions. Nous avons capturé ces deux espèces en utilisant un système attractif composé d’écrans de tissu noir/bleu/ noir muni de film adhésif, afin de retenir toutes les glossines posées et de pouvoir mesurer la hauteur à laquelle elles se sont posées, ainsi que leur rythme d’activité en fonction de l’heure de la journée. L’étude a eu lieu dans deux zones du sud du Burkina Faso : Kartasso en amont du fleuve Mouhoun, où seule G. p. gambiensis est présente, et Folonzo sur le fleuve Comoé, où les deux espèces cohabitent. Les résultats, sur 3 800 glossines capturées, montrent une forte prédominance des captures de G. tachinoides par rapport à G. p. gambiensis à Folonzo (84 % contre 16 % des captures respectivement). À Kartasso, où elle est seule, G. p. gambiensis est capturée en moyenne à 46 cm du sol. À Folonzo, G. p. gambiensis est en moyenne attrapée à une hauteur de 65 cm, et G. tachinoides à 55 cm, ces différences de hauteurs étant significatives. Les femelles sont capturées en général plus haut que les mâles. Les deux espèces montrent un rythme d’activité similaire en fonction de l’heure de capture, mais seule G. p. gambiensis réduit sa hauteur de vol aux heures les plus chaudes. Plusieurs hypothèses, non exclusives, sont évoquées pour expliquer ces hauteurs de capture différentes : la nature de la galerie forestière, un comportement d’approche qui différerait entre espèces, mais aussi la possibilité de phénomènes de compétition interspécifique en relation avec l’utilisation de ressources énergétiques limitées (métabolisme lié à la proline). Sont également discutées les conséquences possibles de ces différences de comportement sur les méthodes de lutte, par exemple lors de l’utilisation d’attractifs olfactifs qui pourraient avoir des efficacités distinctes en fonction de la hauteur de vol.

Insecticidal activity of three plants extracts on the cowpea pod sucking bug, Clavigralla tomentosicollis, STAL (Hemiptera: Coreidae)

In Burkina Faso, farmers commonly use insecticidal plants for crop protection. To understand how insecticidal plant works (their mode of action), we carried out a bioassay on Clavigralla tomentosicollis, the cowpea pod sucking bugs with three insecticidal plants, Cassia nigricans V., Cymbopogon schoenanthus S. and Cleome viscosa L. Three modes of exposures (1) direct contact application, (2) stomach poisoning activity (3) and inhalation toxicity activity, were tested. The results showed a potent contact and stomach toxicity on 1st instars larvae regardless of the three crude extracts. But the plant extracts was less effective with older stages of the insects. A highest effectiveness was recorded with inhalation of vapours of crude extracts regardless of insect stages and type of plants. Implications of these findings are discussed regarding the use of plant extract for controlling pod sucking bugs in cowpea fields.

Roles of clinical and subclinical reactivated herpes simplex virus type 2 infection and human immunodeficiency virus type 1 (HIV-1)-induced immunosuppression on genital and plasma HIV-1 levels

BACKGROUND

Few longitudinal studies have described the interactions between reactivation of herpes simplex virus type 2 (HSV-2) infection (hereafter, "HSV-2 reactivation") and genital and systemic replication of human immunodeficiency virus type 1 (HIV-1).

METHODS

Women in Burkina Faso who were seropositive for both HIV-1 and HSV-2 were enrolled in a randomized placebo-controlled trial of therapy to suppress reactivation of HSV-2 infection (hereafter, "HSV suppressive therapy"). During the baseline phase, 6 enriched cervicovaginal lavage specimens were obtained over 12 weeks to detect and quantify the HIV-1 RNA and HSV-2 DNA loads.

RESULTS

Women with genital ulcer disease (GUD) detected at least once were more likely than women in whom GUD was not detected (risk ratio [RR], 1.23; 95% confidence interval [CI], 1.09-1.37) to have genital HIV-1 RNA detected during >or=1 visit. Similarly, women with genital HSV-2 DNA detected during >or=1 clinic visit were more likely than women in whom genital HSV-2 DNA was not detected (RR, 1.17; 95% CI, 1.01-1.34) to have genital HIV-1 RNA detected at least once. In addition, the mean genital HIV-1 RNA loads for women with GUD detected during >or=1 visit and women with HSV-2 genital shedding detected during >or=1 visit were greater than that for women in whom genital HSV-2 DNA or GUD was never detected. The plasma HIV-1 RNA load was increased among women for whom >or=1 visit revealed GUD (+0.25 log(10) copies/mL; 95% CI, -0.05-0.55) or genital HSV-2 DNA (+0.40 log(10) copies/mL; 95% CI, 0.15-0.66), compared with women who did not experience GUD or HSV-2 genital shedding, respectively. The association of HSV-2 reactivations on HIV-1 replication tended to be stronger in patients with a higher CD4(+) cell count (i.e., >500 cells/microL). The contribution of HSV-2 to HIV-1 replication among women with CD4(+) cell count of <or=500 cells/microL was reduced because almost all experienced HIV-1 genital shedding.

CONCLUSIONS

Both clinical and subclinical HSV-2 reactivations play a role in increasing the rate of HIV-1 replication. HSV suppressive therapy is a promising tool for HIV control. Initiation of such therapy when the CD4(+) cell count is >500 cells/microL deserves further investigation.

CLINICAL TRIALS REGISTRATION

The ANRS 1285 Study is registered with the National Institutes of Health (registration number NCT00158509).

Longitudinal effect following initiation of highly active antiretroviral therapy on plasma and cervico-vaginal HIV-1 RNA among women in Burkina Faso

BACKGROUND

Highly active antiretroviral therapy (HAART) could decrease HIV-1 transmissibility by reducing genital and plasma HIV-1 RNA.

METHODS

We evaluated the effect of HAART on genital and plasma HIV-1 RNA in a cohort of 39 antiretroviral-naïve women in Burkina Faso. Cervico-vaginal lavages were collected before HAART initiation and at six visits over 28 weeks while on HAART. Blood samples were collected at baseline and at three and four visits for CD4 and plasma HIV-1 RNA measurements, respectively.

RESULTS

Before HAART, 72% of women had detectable genital HIV-1 RNA. After 18 weeks on HAART, only one woman (2.5%) had detectable plasma HIV-1 RNA and two women (5.1%) had detectable genital HIV-1 RNA. Similar results were observed at each follow-up visit. However, 16/34 (47%) women with consistently undetectable plasma HIV-1 RNA shed HIV-1 at least once between weeks 18 and 28. In samples with detectable genital HIV-1, the mean quantity of HIV-1 RNA decreased from 3.87 prior to HAART to 3.04 log(10) copies/mL at last visit (median 29 weeks; a 6.8-fold decrease in absolute number of copies/mL) (p = 0.04). A significant median CD4 lymphocyte cell gain of 121 cells/muL (interquartile range 59 to 204) was measured between pre-HAART and last visit.

CONCLUSION

These findings suggest that HAART could play a role in reducing HIV transmission in Africa; however, they underscore the need to emphasise safe sex practices with patients taking HAART.

N-acetyl-β-d-hexosaminidase from Trichomonas vaginalis: substrate specificity and activity of inhibitors

Among chitinolytic activities previously described in Trichomonas vaginalis, N-acetyl-beta-D-hexosaminidase (NAHase) was the enzyme system expressing the highest level of specific activity. We report here some biochemical characteristics of NAHase purified from T. vaginalis. We found at first that the use of 4-methylumbellifferyl-substrate was responsible for a substrate affinity for the enzyme, about 1000-fold higher than those when using p-nitrophenyl-substrates (PNP). Whereas the optimum pH was 7.0 using PNP-substrate, it was at 4.5 using 4-methylumbelliferyl-substrate. Four different substrates were compared for their action on T. vaginalis NAHase and we have found that N-acetyl-beta-D-glucosaminide substrate was the most specific. DTT had no effect on enzyme activity suggesting that thiol group are not involved at the catalytic site. The use of previously described inhibitors showed a positive correlation between trichomonacidal activity and NAHase inhibition.

The chitinase system from Trichomonas vaginalis as a potential target for antimicrobial therapy of urogenital trichomoniasis

Chitinolytic activities in Trichomonas vaginalis membrane extracts were assessed by assays of three enzyme systems: N-acetyl-beta-D-hexosaminidase (NAHase), chitobiosidase and chitotriosidase. N-acetyl-beta-D-hexosaminidase was the enzyme that showed the highest specific activity. After successive subcutaneous inoculations into mice and parasite recovery in culture, the enzyme activities increased significantly with the number of inoculations for up to eight passages. In addition, enzyme activities were maximum at the logarithmic phase of growth. Glycol chitin, a chitinase substrate, enhanced all chitinolytic activities by about 30% and a clear-cut correlation is shown between the capacity for erythrocyte lysis by parasites and NAHase expression. Chitobiosidase and chitotriosidase activities were both inhibited at 58% and 100%, respectively, by allosamidine, a chitinase inhibitor used at 3 microM, whereas NAHase activity was not affected. Seven putative NAHase inhibitors (compounds n, 1-7), ureido and thioureido derivatives of 2-amino-2-deoxy-D-glucose were evaluated and five of them had K(i) values in the range 30-70 microM. The most active compound (compound 6) was functionally competitive with respect to the substrate with a K(i) value of 30 microM. The IC(50) values of the most active compounds on T. vaginalis were in the range 62-85 microM. These results indicate that chitinases of T. vaginalis are involved in pathogenicity and they could be an interesting target for drugs since chitinase inhibitors also inhibit parasite growth.

Marked elevation of serum N-acetyl-beta-D-hexosaminidase activity in rheumatoid rheumatoid arthritis

OBJECTIVE

To study N-acetyl-beta-D-hexosaminidase (NAHase) activity in the sera of rheumatoid arthritis (RA) patients and to determine its source.

METHODS

NAHase activity in the serum and synovial fluid of RA patients was measured with p-nitrophenyl beta-N-acetylglucosaminide as substrate. The p-nitrophenol released was measured spectrophotometrically in an ELISA reader. Rabbit articular chondrocytes in primary culture were stimulated with interleukin-1 beta (IL-1 beta).

RESULTS

Serum NAHase activity was higher in 35% of the RA patients than in healthy patients. The median activity was about twice that of the serum of healthy volunteers. RA patients with high serum NAHase activity also had more joint destruction (85%) than those with normal NAHase activity (57%, p < 0.05), but their inflammatory status was similar. The source of NAHase in RA was investigated by assaying it in RA synovial fluids (SF) and measuring its release from articular chondrocytes in primary culture. NAHase activity was detected in all 23 RA SF, at a median concentration that was 2 times that of the serum. NAHase activity in the medium of articular chondrocytes was stimulated by IL-1 beta (p < 0.005 compared to unstimulated cells), suggesting that cartilage is a source of serum and SF NAHase activity.

CONCLUSION

The serum concentration of the matrix hydrolase, NAHase, is higher in destructive RA than in inflammatory RA.

A new photometric assay with bromocresol purple for testing in vitro antitrichomonal activity in aerobic environment

A new colorimetric assay relying on the acidic metabolism of Trichomonas vaginalis was developed for in vitro screening of various compounds against axenically grown trichomonads. Parasites from continuous culture were exposed to series of drug dilutions in a microtiter plate. After an incubation period of 48 h at 37 degrees C, the pH indicator of the medium had changed its colour in non-inhibited cultures due to the production of lactate and acetate. Inhibited cultures showed no colour changes. The use of bromocresol purple, a pH indicator, was suitable for several reasons: it is not toxic at the concentration used in the assay; the absorbance of bromocresol purple at 405 nm showed a linear correlation with both the pH of the medium and the viability of the trichomonads observed microscopically; plates could easily be read by eye or using an enzyme-linked immunosorbant assay (ELISA) reader. By comparison of the decreases in absorbance in test cultures with those in control cultures, IC50 values could be determined. Thus, IC50 of metronidazole was calculated at 25.5 +/- 2.3 mumol/l (n = 5) with the bromocresol purple assay and about 25 mumol/l after microscope observation. Minimal lethal concentrations (MLCs) could be read by eye. This test is now routinely used for anti-trichomonas evaluation of various chemical compounds and natural products.

Synthesis and biological evaluation of ureido and thioureido derivatives of 2-amino-2-deoxy-D-glucose and related aminoalcohols as N-acetyl-beta-D-hexosaminidase inhibitors

Ureido and thioureido derivatives of 2-acetamido-2-deoxy-beta-D-glucose, 1-amino-1-deoxy-D-glucitol and 2-(2-aminoethoxy)ethanol were prepared as N-acetyl-beta-D-hexosaminidase (NAHase) inhibitors and were evaluated on Trichomonas vaginalis NAHase. Although none showed complete inhibition of the enzyme at 100 microM, 1-amino-1-deoxy-D-glucitol derivatives acted as competitive inhibitors of the NAHase of T. vaginalis.

Chitinolytic activities in Trichomonas vaginalis

Chitinolytic activities were identified in the Protozoa Trichomonas vaginalis. Overall chitinase activity assessed using chitine-azure as substrate was 10.93 +/- 1.21 nmoles/min/mg prot. End nonreducing chitobiosidase (exochitinase) and chitotriosidase (endochitinase) activities were shown using p-nitrophenyl-substrates and had specific activities of 4.55 +/- 0.53 and 0.47 +/- 0.06 nmol/min/mg prot, Kmapp. = 1.32 mM and 5 microM and pH optimum = 7.0 and 6.1 respectively. beta-N-acetylhexosaminidase (NAHase) activity was also detected with a specific activity of 5.40 +/- 0.65 nmol/min/mg prot., Kmapp = 0.656 mM and pH optimum at 7.0. No release of these enzymes into the culture medium was found. The possible role of chitinases in T. vaginalis remains to be investigated.

Pseudomonas dacryoadenitis secondary to a lacrimal gland ductule stone

Infectious dacryoadenitis is a rare condition. A case of Pseudomonas dacryoadenitis has not been reported previously. We treated a patient with Pseudomonas dacryoadenitis secondary to obstruction from a lacrimal gland ductule stone. Histologically, the calculus contained hairs.