Lack of Correlation between Seminal and Plasma HIV-1 Viral Loads is Associated with CD4T Cell Depletion in Therapy-naïve HIV-1+ Patients

The present study was conducted to investigate a possible correlation between plasma (PVL) and seminal viral load (SVL) on treatment-naïve HIV-1-infected patients in Vitória, ES, Brazil. We also evaluated whether the progressive immunosuppression associated with HIV disease (as evidenced by declining CD4 T cell counts) has any impact on the correlation between PVL and SVL HIV-1. Viral load on paired blood and semen samples from 56 consecutive treatment-naïve patients were evaluated and compared to CD4 cell counts. Viral load and T cell counts (cells/µl) were determined by NASBA and by flow cytometry, respectively. Overall, a strong positive correlation between PVL and SVL (rho = 0.438, p = 0.001) was observed. However, when patients were grouped according to their CD4 counts, this correlation was only significant among patients with CD4 counts > 200 cells/µl. Results presented here demonstrate the existence of a strong correlation between PVL and SVL on patients with CD4 cell counts > 200 cells/µl, suggesting that this association may correlate with disease progression.

The opossum Didelphis virginiana as a synanthropic reservoir of Trypanosoma cruzi in Dzidzilché, Yucatán, México

In México, the role of mammals in the transmission cycle of Trypanosoma cruzi is poorly known. In the State of Yucatán, an endemic area of Chagas disease, both Didelphis virginiana and D. marsupialis occur sympatrically. However, until now, only the former species had been found infected with T. cruzi. To evaluate the role of D. virginiana in a peridomestic transmission, nine periods of capture-recapture were performed around the village of Dzidzilché, Yucatán. The sex, age, reproductive status, location, and presence of infection with T. cruzi were recorded for each opossum. The chromosome morphology was used to identify the opossum species. T. cruzi was identified by the presence of pseudocysts of amastigotes in cardiac muscle fibers of Balb/c mice inoculated with strains isolated from opossums. However, xenodiagnosis was the best diagnostic method. Triatoma dimidiata, the vector, were collected in and around the opossums' nests, and human dwellings; and were checked for T. cruzi. From 102 blood samples of D. virginiana examined 55 (53.9%) were positive to T. cruzi, the only two D. marsupialis captured were negative. Significant differences were found between infection, and both sex and reproductive condition. Eight out of 14 triatomines collected in peridomestic nests (57.1%), and 32 of 197 captured inside houses (16.3%) were found infected, suggesting a peridomestic transmission. The statistically high abundance of infected opossums and triatomines during the dry season (March to May) suggested the existence of a seasonality in the peridomestic transmission of T. cruzi in Dzidzilché.

Community ecology of the metazoan parasites of pink cusk-eel, Genypterus brasiliensis (Osteichthyes: Ophidiidae), from the coastal zone of the State of Rio de Janeiro, Brazil

Fifty-five specimens of pink cusk-eel, Genypterus brasiliensis Regan, 1903 (Osteichthyes: Ophidiidae) collected from the coastal zone of the State of Rio de Janeiro, Brazil (approx. 21-23°S, 41-45°W), from September 2000 to January 2001, were necropsied to study their parasites. All fish were parasitized by one or more metazoan. Fourteen species of parasites were collected. G. brasiliensis is a new host record for nine parasite species. The larval stages of cestodes and the nematodes were the majority of the parasite specimens collected, with 38.4% and 36.5%, respectively. Cucullanus genypteri was the dominant species with highest prevalence and/or abundance. The parasites of G. brasiliensis showed the typical overdispersed pattern of distribution. Six parasite species showed correlation between the host's total body length and prevalence and abundance. Host sex did not influence prevalence and parasite abundance of any parasite species. The mean diversity in the infracommunities of G. brasiliensis was H= 0.364 ± 0.103, with correlation with the host's total length and without differences in relation to sex of the host. One pair of adult endoparasites (C. genypteri and A. brasiliensis) showed positive covariations between their abundances. Negative association or covariation was not found. Differences between the qualitative and quantitative aspects of the parasite community of G. brasiliensis from Rio de Janeiro and Argentina suggest the existence of two population stocks of pink cusk-eel in the South America Atlantic Ocean.

Triatoma rubrovaria (Blanchard, 1843) (Hemiptera: Reduviidae) I: isoenzymatic and chromatic patterns of five populations from the State of Rio Grande do Sul, Brazil

Triatoma rubrovaria has become the most frequently captured triatomine species since the control of T. infestans in the State of Rio Grande do Sul (RS), Brazil. In order to evaluate the genetic variability of this species, field collections were performed in four municipalities where it has been reported and distant from 75 to 322 km. Specimens were analyzed by color pattern and isoenzymes. Nine enzymatic loci were interpreted from nine enzymatic systems. The Santiago population was isolated from the others with chromatic monomorphism and diagnostic alleles at Idh and Pgm loci. The study shows the existence of, at least, two distinct populations of T. rubrovaria in RS with different phenotypic and genetic pattern.

First characterization of Candida albicans by random amplified polymorphic DNA method in Nicaragua and comparison of the diagnosis methods for vaginal candidiasis in Nicaraguan women

A total of 106 women with vaginitis in Nicaragua were studied. The positive rate for the identification of Candida species was 41% (44 positive cultures out of 106 women with vaginitis). The sensitivity of microscopic examination of wet mount with the potassium hydroxide (KOH) was 61% and 70% with Gram's stain when using the culture of vaginal fluid as gold standard for diagnosis of candidiasis. Among the 44 positives cultures, isolated species of yeast from vaginal swabs were C. albicans (59%), C. tropicalis (23%), C. glabrata (14%) and C. krusei (4%). This study reports the first characterization of 26 C. albicans stocks from Nicaragua by the random amplified polymorphic DNA method. The genetic analysis in this small C. albicans population showed the existence of linkage disequilibrium, which is consistent with the hypothesis that C. albicans undergoes a clonal propagation.

Triatoma rubrovaria (Blanchard, 1843) (Hemiptera, Reduviidae, Triatominae) II: trophic resources and ecological observations of five populations collected in the State of Rio Grande do Sul, Brazil

Triatoma rubrovaria has become the most frequently captured triatomine species after the control of T. infestans in the State of Rio Grande do Sul (RS), Brazil. Isoenzymatic and chromatic studies indicate the existence of, at least, two distinct phenotypic patterns of T. rubrovaria in RS. The geographic variation noted through molecular tools may also result in distinct profiles of vectorial potentiality. In order to enhance our understanding of the bionomic knowledge of T. rubrovaria separate batches of the species were collected from different municipalities of RS distant from 72 to 332 km: Santana do Livramento (natural ecotope), Santana do Livramento (artificial ecotope), Santiago (natural ecotope), Canguçu (peridomicile) and Encruzilhada do Sul (natural ecotope). A total of 285 specimens were collected, 85 specimens kept sufficient fecal material in their guts for the precipitin analysis. The results indicated the food eclecticism for this species and the anti-rodent serum showed the highest positivity in most localities. From the total of analyzed samples, only 1.3% of unique positivity for human blood was registered, all of them for Santiago population. This reactivity to human blood may be associated to pastures activities in the field.

Experimental evidence and ecological perspectives for the adaptation of Schistosoma mansoni Sambon, 1907 (Digenea: Schistosomatidae) to a wild host, the water-rat, Nectomys squamipes Brants, 1827 (Rodentia: Sigmodontinae)

Due to the semi aquatic habits and the overlap of the geographical distribution of the water-rat, Nectomys spp., with schistosomiasis endemic areas, these wild rodents are very likely to acquire Schistosoma mansoni infection in their daily activities. The role of the water-rat in the S. mansoni cycle would be substantiated if one could prove that these rodents acquire the parasite during their own activity time, a completely independent time schedule of human activities. To pursue this goal, we performed two field experiments in the municipality of Sumidouro, State of Rio de Janeiro, Brazil, a schistosomiasis endemic area where N. squamipes is found naturally infected. One experiment was devised as a series of observations of activity time of the water-rat. The other experiment was a test of the occurrence of late transmission of S. mansoni to the water-rat. The daily activity pattern showed that the water-rat is active chiefly just after sunset. At both diurnal and late exposition essays the water-rat sentinels got infected by S. mansoni. These findings clarify ecological and behavioral components necessary to the adaptation of S. mansoni to the water-rat as a non human definitive host and the existence of a transmission cycle involving this animals as a reservoir.

The association of genetic markers and malaria infection in the Brazilian Western Amazonian region

Almost all individuals (182) belonging to an Amazonian riverine population (Portuchuelo, RO, Brazil) were investigated for ascertaining data on epidemiological aspects of malaria. Thirteen genetic blood polymorphisms were investigated (ABO, MNSs, Rh, Kell, and Duffy systems, haptoglobins, hemoglobins, and the enzymes glucose-6-phosphate dehydrogenase, glyoxalase, phosphoglucomutase, carbonic anhydrase, red cell acid phosphatase, and esterase D). The results indicated that the Duffy system is associated with susceptibility to malaria, as observed in other endemic areas. Moreover, suggestions also arose indicating that the EsD and Rh loci may be significantly associated with resistance to malaria. If statistical type II errors and sample stratification could be ruled out, hypotheses on the existence of a causal mechanism or an unknown closely linked locus involved in susceptibility to malaria infection may explain the present findings.

Larval biometry of Simulium rubrithorax (Diptera: Simuliidae) and size comparison between populations in the states of Minas Gerais and Roraima, Brazil

The number of larval instars of Simulium (Hemicnetha) rubrithorax Lutz (Diptera: Nematocera) was determined using the lateral length of the head capsule. In this study 1,035 larvae, of different sizes, were measured (639 from the state of Roraima and 396 from the state of Minas Gerais). A frequency distribution analysis was carried out on the measurements of the lateral length of the head capsule to determine the number of larval instars. The limits of each instar were defined by the lower frequency of the measurements falling in a range of values, by the presence of the "egg burster" that characterizes the first larval instar, and by the developmental stage of the gill histoblast. The determination of the instar number was tested using a Student's t-test (p < 0.05), the Dyar rule and the Crosby growth rule. The results indicate the existence of 7 larval instars for this species, although this result was not in accordance to the Crosby rule. Last-instar larvae from two widely separated geographical populations (Roraima and Minas Gerais), collected in habitats with different water temperature were compared and no differences (p > 0.05) were observed between them.

Isoenzymatic analysis of four Anopheles (Kerteszia) bellator Dyar & Knab (Diptera: Culicidae) populations

Anopheles bellator is a small silvatic bromelia-breeding mosquito and is a primary human malaria vector species in Southern Brazil. The bromelia-breeding habitat of the species should accompany the Atlantic forest coastal distribution, where bromeliads are abundant. Nonetheless, records on An. bellator collections show a gap in the species geographical distribution. An. bellator has been recorded in Southern Brazil and in the Brazilian states of Bahia and Paraíba. It appers again in the island of Trinidad, in Trinidad and Tobago. The aim of this work was to measure gene flow between different populations of An. bellator collected in the northern and southern extremes of the geographic distribution of this species. Mosquitoes were captured in forest borders in Santa Catarina, São Paulo, and Bahia states in Brazil and in the island of Trinidad in Republic of Trinidad and Tobago. Genetic distances varied between 0.076 and 0.680, based on enzymatic profiles from 11 distinct isoenzymes. Results indicate the existence of low-level gene flow between Brazilian populations of An. bellator, and a gene flow was even lower between the Brazilian and the Trinidad populations. This finding lead us to hypothesize that An. bellator did not spread along the coast, but reached northeastern areas through inland routes.

Effect of angiotensin II and losartan on the phagocytic activity of peritoneal macrophages from Balb/C mice

Angiotensin II (AII), a product of rennin-angiotensin system, exerts an important role on the function of immune system cells. In this study, the effect of AII on the phagocytic activity of mouse peritoneal macrophages was assessed. Mice peritoneal macrophages were cultured for 48 h and the influence of different concentrations of AII (10-14 to 10-7 M) and/or losartan, 10-16 to 10-6 M), an AT1 angiotensin receptor antagonist, on phagocytic activity and superoxide anion production was determined. Dimethylthiazoldiphenyltetrazolium bromide reduction and the nucleic acid content were used to assess the cytotoxicity of losartan. A stimulatory effect on phagocytic activity (P < 0.05) was observed with 10-13 M and 10-12 M AII concentrations. The addition of losartan (up to10-14 M) to the cell cultures blocked (P < 0.001) the phagocytosis indicating the involvement of AT1 receptors. In contrast, superoxide anion production was not affected by AII or losartan. The existence of AT1 and AT2 receptors in peritoneal macrophages was demonstrated by immunofluorescence microscopy. These results support the hypothesis that AII receptors can modulate murine macrophage activity and phagocytosis, and suggest that AII may have a therapeutic role as an immunomodulatory agent in modifying the host resistance to infection.

The sexual behaviour of Panstrongylus megistus (Hemiptera: Reduviidae): an experimental study

The factors affecting the sexual behaviour of Panstrongylus megistus were studied under laboratory conditions. A general description of mating behaviour is presented for this species. The effect of the time elapsed after the first imaginal feeding on the mating frequency, the motivation of males to mate and the rejection behaviour by females, were analyzed. We also determined the number of copulas accepted by females of this species. Finally, the possible existence of a sexual chemical signal promoting male aggregation around mating couples was evaluated. Results showed that mating frequency increased with the time elapsed since the first adult meal. Despite the number of male copulatory attempts did not change as a function of time, the rejection behaviour of females became gradually less frequent. Females rejected mating by means of body flattening on the substrate, abdominal movements, evasion or stridulation. After a single copula, females did not usually accept to mate again. Neither male nor female aggregation around mating couples was observed, suggesting the absence of a sexual assembling pheromone in P. megistus.

Identification of casein kinase 1, casein kinase 2, and cAMP-dependent protein kinase-like activities in Trypanosoma evansi

Trypanosoma evansi contains protein kinases capable of phosphorylating endogenous substrates with apparent molecular masses in the range between 20 and 205 kDa. The major phosphopolypeptide band, pp55, was predominantly localized in the particulate fraction. Anti-alpha and anti-beta tubulin monoclonal antibodies recognized pp55 by Western blot analyses, suggesting that this band corresponds to phosphorylated tubulin. Inhibition experiments in the presence of emodin, heparin, and 2,3-bisphosphoglycerate indicated that the parasite tubulin kinase was a casein kinase 2 (CK2)-like activity. GTP, which can be utilized instead of ATP by CK2, stimulated rather than inactivated the phosphorylation of tubulin in the parasite homogenate and particulate fraction. However, GTP inhibited the cytosolic CK2 responsible for phosphorylating soluble tubulin and other soluble substrates. Casein and two selective peptide substrates, P1 (RRKDLHDDEEDEAMSITA) for casein kinase (CK1) and P2 (RRRADDSDDDDD) for CK2, were recognized as substrates in T. evansi. While the enzymes present in the soluble fraction predominantly phosphorylated P1, P2 was preferentially labeled in the particulate fractions. These results demonstrated the existence of CK1-like and CK2-like activities primarily located in the parasite cytosolic and membranous fractions, respectively. Histone II-A and kemptide (LRRASVA) also behaved as suitable substrates, implying the existence of other Ser/Thr kinases in T. evansi. Cyclic AMP only increased the phosphorylation of histone II-A and kemptide in the cytosol, demonstrating the existence of soluble cAMP-dependent protein kinase-like activities in T. evansi. However, no endogenous substrates for this enzyme were identified in this fraction. Further evidences were obtained by using PKI (6-22), a reported inhibitor of the catalytic subunit of mammalian cAMP-dependent protein kinases, which specifically hindered the cAMP-dependent phosphorylation of histone II-A and kemptide in the parasite soluble fraction. Since the sum of the values obtained in the parasite cytosolic and particulate fractions were always higher than the values observed in the total T. evansi lysate, the kinase activities examined here appeared to be inhibited in the original extract.

A mucin like gene different from the previously reported members of the mucin like gene families is transcribed in Trypanosoma cruzi but not in Trypanosoma rangeli

Trypanosoma cruzi expresses mucin like glycoproteins encoded by a complex multigene family. In this work, we report the transcription in T. cruzi but not in T. rangeli of a mucin type gene automatically annotated by the T. cruzi genome project. The gene showed no nucleotide similarities with the previously reported T. cruzi mucin like genes, although the computational analysis of the deduced protein showed that it has the characteristic features of mucins: a signal peptide sequence, O-glycosylation sites, and glycosylphosphatidylinositol (GPI) anchor sequence. The presence in this gene of N- terminal and C- terminal coding sequences common to other annotated mucin like genes suggests the existence of a new mucin like gene family.

Mast cell changes in experimental diabetes: focus on attenuation of allergic events

The prevalence of atopic diseases and diabetes is increasing worldwide though the concurrence of these pathologies in individual patients is found less frequent than it would be predicted. Moreover, co-existence of diabetes and allergy is generally marked by attenuation of their respective symptoms, and effective treatment of one disease exacerbates the other. This review gives an update of the state-of-the-art concerning the intercurrence of allergy and diabetes, particularly focusing on the consequences to the allergen-evoked vascular and cellular changes. It is proposed that the reduction in mast cell numbers and reactivity may be a pivotal mechanism behind the mutual exclusion phenomenon.