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41.
Trypanosoma evansi (Trypanosomatidae, Kinetoplastida) is a salivarian trypanosomatid that infects eight mammal orders spread over America, Europe and Asia. In Brazil, T. evansi is the etiological agent of Mal de Cadeiras, a horse disease very often described in the region known as Pantanal do Mato Grosso. Few data concerning the genetic diversity and biology of subpopulations of T. evansi that circulate in Brazil are available. The factors that modulate the interaction of this parasite with its hosts also remain to be elucidated. Here we evaluated the course of experimental infection of six T. evansi isolates derived from domestic and wild animals in Swiss-Webster mice and three Mus musculus lineages. The follow-up included biological, immunological as well as biochemical and hematological parameters. The same isolates as well as three others were characterized by pulsed-field electrophoresis. Our results showed that T. evansi isolates displayed significant differences regarding behavior and morbidity patterns in the distinct mouse lineages. Nevertheless, these differences could not be correlated with pulsed-field electrophoresis profiles. Indeed, concerning this molecular marker, only microheterogeneity was observed. Moreover, we observed that the outcome of the infection is defined by both host genetic background and peculiarities (virulence factors) of the distinct T. evansi isolates. Anemia and hypoglycemia were the only features that could be observed in all mouse lineages, independently of the inoculated T. evansi subpopulation. In addition, our data also show that Mus musculus is a suitable model host for the study of the different pathogenetic features of T. evansi infection. 相似文献
42.
Mello MA Mascarenhas RE Ferraro GA Harn D Galvão-Castro M Bou-Habib DC 《Medical microbiology and immunology》2005,194(1-2):61-65
Patients infected with HIV-1 develop a potent humoral immune response against the virus, but HIV-1 primary isolates are remarkably resistant to neutralizing antibodies. Considering that the envelope glycoprotein of HIV-1 (gp120/41) is heavily glycosylated, we investigated whether anti-carbohydrate antibodies could inhibit HIV-1 infection in vitro. We studied the neutralizing activity of three monoclonal antibodies (mAbs) raised to carbohydrates of Schistosoma mansoni, against seven primary isolates of HIV-1. Assays were performed infecting peripheral blood mononuclear cells from normal donors with viral isolates previously treated with mAbs. Viral strains used were tropic for the coreceptors CCR5, CXCR4, and dual-tropic ones. We found that the anti-glycan mAbs vigorously inhibited HIV-1 infection, regardless of the preferential coreceptor usage of the isolate, in a dose-response manner. Importantly, five isolates were resistant to neutralization by two HIV-1 antibody-positive human sera endowed with potent anti-HIV-1 inhibitory activity. Our findings suggest that carbohydrates of the HIV-1 viral envelope may be a target of an effective humoral immune response elicited by vaccination.The first two authors contributed equally to this work 相似文献
43.
Seroprevalence of Kaposi's sarcoma-associated herpesvirus/human herpesvirus 8 in several regions of Italy 总被引:2,自引:0,他引:2
Calabrò ML Sheldon J Favero A Simpson GR Fiore JR Gomes E Angarano G Chieco-Bianchi L Schulz TF 《Journal of human virology》1998,1(3):207-213
OBJECTIVE: To study the seroprevalence of Kaposi's sarcoma-associated herpesvirus/human herpesvirus type 8 (KSHV/HHV-8) in 779 Italian blood donors. STUDY DESIGN/METHODS: Sera were tested for antibodies to a latency-associated nuclear antigen (LANA) and a capsid related protein encoded by ORF65. RESULTS: Among all Italian donors, 17.7% and 18.7% had antibodies to LANA and ORF65 protein, respectively, and 24.1% had antibodies to at least one antigen. KSHV/HHV-8 seroprevalence was higher in the Po valley and in Sardinia than close to the sub-Alpine Veneto region, Tuscany, or Apulia. KSHV/HHV-8 seroprevalence was almost equally distributed between men and women but increased in the older age groups. CONCLUSIONS: The regional differences and age distribution in seroprevalence agree partially with the incidence of classic KS in Italy. The rarity of classic KS in KSHV/HHV-8-infected subjects and the equal gender distribution of seroprevalence suggest that other cofactors may contribute to KS development in human immunodeficiency virus type 1 (HIV-1)-uninfected individuals. 相似文献
44.
Melo Cavalcante AA Rubensam G Picada JN Gomes da Silva E Fonseca Moreira JC Henriques JA 《Environmental and molecular mutagenesis》2003,41(5):360-369
Fresh and processed cashew (Anacardium occidentale) apple juice (CAJ) are among the most popular drinks in Brazil. Besides their nutritional benefits, these juices have antibacterial and antitumor potential. The chemical constituents of both the fresh juice and the processed juice (cajuina) were analyzed and characterized as complex mixtures containing high concentrations of vitamin C, various carotenoids, phenolic compounds, and metals. In the present study, these beverages exhibited direct and rat liver S9-mediated mutagenicity in the Salmonella/microsome assay with strains TA97a, TA98, and TA100, which detect frameshifts and base pair substitution. No mutagenicity was observed with strain TA102, which detects oxidative and alkylating mutagens and active forms of oxygen. Both CAJ and cajuina showed antioxidant activity as determined by a total radical-trapping potential assay. To test whether this antioxidant potential might result in antimutagenesis, we used a variation of the Salmonella/microsome assay that included pre-, co-, and posttreatment of hydrogen peroxide-exposed Salmonella typhimurium strain TA102 with the juices. CAJ and cajuina protected strain TA102 against mutation by oxidative damage in co- and posttreatments. The antimutagenic effects during cotreatment with hydrogen peroxide may be due to scavenging free radicals and complexing extracellular mutagenic compounds. The protective effects in posttreatment may be due to stimulation of repair and/or reversion of DNA damage. The results indicate that CAJ and cajuina have mutagenic, radical-trapping, antimutagenic, and comutagenic activity and that these properties can be related to the chemical constituents of the juices. 相似文献
45.
Gomes AR Sanches IS Aires de Sousa M Castañeda E de Lencastre H 《Microbial drug resistance (Larchmont, N.Y.)》2001,7(1):23-32
The first study on the molecular characterization of methicillin-resistant Staphylococcus aureus (MRSA) isolates from Colombia was performed as part of a global surveillance established by the CEM/NET Initiative, under Project RESIST. Seventy-six MRSA isolates recovered from five hospitals during 1996-1998 were analyzed by the hybridization of ClaI restriction digests with mecA- and Tn554-specific probes, and by pulsed-field gel electrophoresis (PFGE) of chromosomal SmaI digests. All MRSA isolates, with one exception, belonged to a single clonal type II::NH::D. This clone, which was previously described among MRSA isolates recovered in the early 1990s in European and New York and South American hospitals, showed resistance to beta-lactam antibiotics only and appeared to be associated almost exclusively with pediatric infections ("Pediatric clone" of MRSA). While sharing identical molecular typing properties with the Pediatric clone, the Colombian isolates differed by extensive multidrug resistance and were recovered from patients of all ages. It is also noteworthy that the Brazilian clone of MRSA (XI::B::B), another multidrug-resistant international clone currently widely spread in Brazil, Argentina, Uruguay, Chile, and also in several European countries, was completely absent from this set of isolates from Colombia. 相似文献
46.
Evidence for a link between iron metabolism and Nramp1 gene function in innate resistance against Mycobacterium avium. 总被引:1,自引:0,他引:1 下载免费PDF全文
In the mouse, the progression of the Mycobacterium avium infection is highly dependent on the Nramp1 gene. Strains of mice that express the Nramp1D169 allele are highly susceptible to M. avium infections, while Nramp1G169 strains of mice can control them. Recently, the Nramp1 gene has been cloned and characterized as coding a transmembrane protein, probably involved in divalent cation transport. One possible function of this protein could be the transport of iron out of the parasite-harbouring phagosome. Previous work in our lab has shown both in vitro (in macrophage cultures) and in vivo, that the growth rate of M. avium is highly dependent on the amount of iron available in the system. To try to correlate this with the Nramp1 gene function, BALB/c (susceptible) and C.D2 (resistant) congenic mice were treated for 20 days with different doses of iron-dextran, so as to induce different degrees of iron overload, and infected with M. avium 2447. Iron administration increased M. avium growth in infected organs in a dose-dependent manner at the same time as it decreased the difference in mycobacterial growth between the two mouse strains. These results indicate that an excess of iron hampers Nramp1-encoded function, strongly suggesting a direct involvement of the Nramp1-encoded protein in the transport of this cation. 相似文献
47.
Paulo AC Gomes MC Casinhas AC Horta A Domingos T 《IMA journal of mathematics applied in medicine and biology》2000,17(3):201-212
The high vaccination coverage required to eradicate communicable diseases like measles, mumps and rubella, with a single dose of vaccine, has prompted many countries to introduce a second dose. In this paper we investigate the conditions to eradicate childhood diseases with multiple doses of vaccine by obtaining explicit analytical solutions to the classical compartment model that assumes an age-independent force of infection and conceptualizes the host population as divided into maternally protected (P), susceptibles (S), latents (E), infectious (I), and removed (R). The solutions allow a quantitative discussion of the long-term impact of vaccination schedules with an arbitrary number of doses of vaccine. It becomes possible to determine the effect of the number of doses, ages at vaccination, and coverage rates of vaccines against childhood diseases. In an example with a two-dose vaccination schedule against measles, we show that, in spite of a second dose, a high (> 90%) immunization coverage in the first dose is still crucial to achieve eradication. With a high first-dose coverage, however, eradication is relatively insensitive to the age of the second dose and requires only moderate coverage rates in the latter. 相似文献
48.
The patterns of exochorion ornaments on eggs of seven South American Lutzomyia sand fly species were analyzed by scanning electron microscopy (SEM): Lutzomyia (Lutzomyia) cruzi (Mangabeira 1938), Lutzomyia (Micropygomyia) evandroi (Costa Lima and Antunes 1936), L. (Nyssomyia) intermedia (Lutz and Neiva 1912), L. longipalpis (Lutz and Neiva 1912), L. migonei (Franca 1920), L. (Nyssomyia) neivai (Pinto 1926), and L. renei (Martins, Falcao, and Silva 1957). Different patterns were observed, which showed the distinction between some species. Egg ornaments in L. cruzi and L. longipalpis appear as single, parallel, unconnected ridges, whereas eggs of L. migonei appear as single, parallel, connected ridges. Eggs of L. (Nyssomyia) intermedia and L. (N.) neivai present a new variation of the single, unconnected, parallel ridges pattern: small tubercles are present, distributed between the ridges. Eggs of L. renei present an elliptical pattern, with most structures connected by straight ridges. Eggs of L. (M.) evandroi present a polygonal pattern, with alternate rows of small and large hexagons. Our data emphasize the advantages of the SEM approach in the study of the exochorion patterns of Lutzomyia eggs and in the distinction of the sand fly species. 相似文献
49.
Tania A. T. Gomes M?nica A. M. Vieira Cecilia M. Abe Daleth Rodrigues Patricia M. Griffin S?nia R. T. S. Ramos 《Journal of clinical microbiology》1998,36(12):3609-3613
The correlation between various adherence patterns and adherence-related DNA sequences in Escherichia coli isolates from 1- to 4-year-old children with and without diarrhea in São Paulo, Brazil, was evaluated. A total of 1,801 isolates obtained from 200 patients and 200 age-matched controls were studied. The adherence patterns found were classified as diffuse, aggregative, aggregative in a 6-h assay, aggregative predominantly in coverslips, localized, localized-like, and noncharacteristic. In general, the DNA sequences used as probes showed excellent specificities (>93%), but their sensitivities varied. Thus, the results of bioassays and assays with DNA probes normally used to search for adherent E. coli did not correlate well, and the best method for the identification of these organisms in the clinical research setting remains controversial. Isolates presenting diffuse adherence or hybridizing with the related daaC probe, or both, were by far the most frequent in patients (31.5, 26.0, and 23.0%, respectively), followed by isolates presenting aggregative adherence or hybridizing with the related EAEC probe, or both (21.5, 13.0, and 10.5%, respectively). None of the different combinations of adherence patterns and adherence-related DNA sequences found were associated with acute diarrhea.The first step in the establishment of the diarrheal diseases caused by the various categories of diarrheagenic Escherichia coli is adherence to epithelial cells of the intestinal mucosa. In vitro assays with eukaryotic cell lines (HeLa and HEp-2 cells) have identified three distinct adherence patterns among fecal isolates of E. coli: localized, diffuse, and aggregative (37, 38, 41). Localized adherence (LA) is characterized by formation of bacterial microcolonies on a restricted area(s) of the cell surface, while diffuse adherence (DA) is the scattered attachment of bacteria over the whole surface of the cell (41). The pattern of aggregative adherence (AA) consists of bacterial attachment to the cells and the intervening cell growth surface in a stacked brick-like lattice (37).The LA pattern was first detected in strains classified as enteropathogenic E. coli (EPEC) among serogroups associated with outbreaks of infantile diarrhea (41). Although E. coli strains exhibiting DA (DAEC) have been isolated at similar frequencies from feces of infants and young children with acute diarrhea and nondiarrheic controls in some populations (3, 10, 11, 14, 18), they were significantly associated with diarrhea in other settings (1, 17, 24, 29, 33). E. coli strains showing AA, termed enteroaggregative E. coli (EAEC), have been linked to sporadic persistent diarrhea (3, 4, 7, 10, 13, 26, 27, 44) and to outbreaks of diarrhea in both developing and developed countries (8, 12, 28, 43). However, the role of EAEC in acute diarrhea is still controversial: some studies have shown a correlation (7, 23, 25, 27, 34, 37), but others (1, 3, 6, 10, 11, 13–15, 17, 18, 24, 26, 29, 33, 44) have not.DNA probes derived from adherence-related sequences have been constructed (2, 5, 16, 31, 36) and used in hybridization assays for the detection of the different established and putative categories of diarrheagenic E. coli in many epidemiological studies.We evaluated the relationship between the LA, DA, and AA patterns and hybridization with adherence-related DNA sequences and tested children 1 to 4 years old with and without acute diarrhea for the presence of adherent E. coli strains. 相似文献
50.
Abath FG Xavier EM Allen R Gomes YM Lucena-Silva N Baliza M Simpson AJ 《Parasitology research》2000,86(9):745-752
Sm13, a 13-kDa Schistosoma mansoni tegumental antigen, is one of the principal polypeptides recognized by antibodies from mice protectively vaccinated with
adult-worm tegumental membranes. To obtain the complete gene encoding Sm13 we subcloned and sequenced a cDNA and a fragment
of a genomic clone. The collated sequence contains 1088 nucleotides and represents the full-length open reading frame of the
gene, encoding a protein of 104 amino acids with a calculated molecular mass of 11,923 Da, compatible with the native protein
identified in the tegumental membranes. The sequence derived from genomic DNA contains a 45-nucleotide intron. The analysis
of the predicted protein suggests the presence of both N- and C-terminal hydrophobic membrane-spanning segments, and the coding
region contains no homology in the currently available data bases. Additionally, the coding region is preceded by putative
CCAAT and TATA boxes that may be involved in the control of expression. Western-blot analysis and indirect immunofluorescence
resulted in the identification of a 13-kDa protein (Sm13) in the tegument of adult worms. The present study reveals that Sm13
behaves as an integral membrane protein upon partitioning in Triton X-114 and that it is present in worms of 3 weeks or older
but not in schistosomula or miracidia. Moreover, it is also specifically recognized by sera from some schistosomiasis patients
in enzyme-linked immunosorbent assay and Western-blot analysis, suggesting that it is immunogenic in human schistosomiasis.
Received: 17 February 2000 / Accepted: 22 March 2000 相似文献