Current status and application of lactic acid bacteria in animal production systems with a focus on bacteria from honey bee colonies.

Lactic acid bacteria (LAB) are widely distributed in nature and, due to their beneficial effects on the host, are used as probiotics. This review describes the applications of LAB in animal production systems such as beekeeping, poultry, swine and bovine production, particularly as probiotics used to improve health, enhance growth and reproductive performance. Given the importance of honeybees in nature and the beekeeping industry as a producer of healthy food worldwide, the focus of this review is on the coexistence of LAB with honeybees, their food and environment. The main LAB species isolated from the beehive and their potential technological use are described. Evidence is provided that 43 LAB bacteria species have been isolated from beehives, of which 20 showed inhibition against 28 species of human and animal pathogens, some of which are resistant to antibiotics. Additionally, the presence of LAB in the beehive and their relationship with antibacterial properties of honey and pollen is discussed. Finally, we describe the use of lactic bacteria from bee colonies and their antimicrobial effect against foodborne pathogens and human health. This review broadens knowledge by highlighting the importance of honeybee colonies as suppliers of LAB and functional food.

Lost forever? Ecosystem functional changes occurring after agricultural abandonment and forest recovery in the semiarid Chaco forests.

Semiarid forests are worldwide threatened by land use changes, particularly agriculture. However, in some cases, due to particular economic or social processes, agriculture ends and forests may or may not recover to their original state. Using different databases and satellite images integrated into a geographical information system, we located in the central region of the semiarid Chaco forests of Argentina adjacent land use patches of secondary forest (SF), remnant forest (RF) and crops (CP). Using a chronosequence approach, we evaluated changes in the fraction of the photosynthetic active radiation absorbed by the vegetation (FAPAR) between SF and RF and CP, using the enhanced vegetation index (EVI). We evaluated both intra and inter-annual changes in EVI mean (EVImean), EVI maximum (EVImax), EVI minimum (EVImin), and EVI relative range (EVIrr) as descriptors of FAPAR dynamics and analyzed their changes through time (2000 to 2010) and their relation to rainfall. Secondary forests showed higher seasonality and higher EVImean values than RF, but differences disappeared as time since agricultural abandonment increased, suggesting that SF recover their functioning (when compared to RF) after 10 to 15 years. Our results suggest that Chaco's SF have intermediate seasonal patterns in-between RF and CP, as expected by successional theory, and that FAPAR interception by RF appears to be dependent on previous year's precipitation. We found that, although all land uses showed similar precipitation use efficiency (PUE), SF and cropland's productivity were less stable across the years and showed faster increases or decreases compared to RF, depending on precipitation (higher precipitation marginal response- PMR). Our results suggest that at least some aspects of ecosystem functioning can be restored after agricultural abandonment. Future research that combines floristic and structural changes is necessary to fully understand secondary forests regrowth process after agricultural abandonment in the Chaco region.

Perspectivas, conceptualizaciones y sentidos en tramas de formación inicial del profesorado: la construcción de la profesión del profesor de psicología / Perspectives, conceptualizations and senses into the wefts of early teaching education: the construction of psychology teacher profession

El trabajo analiza perspectivas y conceptualizaciones de Formadores de Profesores de Psicología en Universidad de Buenos Aires. Objetivo: describir la elaboración reflexiva de quienes acompañan, ayudan y co-construyen problemas y estrategias en la Praxis Formativa del Profesorado. Estudio descriptivo y exploratorio con análisis cualitativos. Categorías del enfoque socio-cultural y modelos contextualistas del cambio cognitivo son entramados con criterios, límites y modalidades formativas. Se administró el Cuestionario de Conceptualizaciones y Creencias del Formador de Profesores de Psicología a 18 Tutores y 21 Co-tutores de "Didáctica Especial y Prácticas de Enseñanza en Psicología". Se construyen figuras de enunciación discursiva de Tutores y Co-Tutores, con lo que piensan que enseñan y sus alumnos aprenden, y lo que favorece o dificulta la construcción del rol del profesor de Psicología. Resulta relevante su valoración de la comunidad de práctica y su percepción de tensiones entre la profesión de psicólogo/a y la de profesor/a de psicología.

The work analyses perspectives and conceptualizations from Teachers of Psychology at Buenos Aires University. Aim: to describe the relective elaboration developed by those who accompany, help and jointly build problems and strategies in Educational Modeling Praxis. Descriptive and exploratory study with qualitative analysis. Socio-cultural approach categories and contextualist models of cognitive change are entwined with criterion, limits and types of educational processes. A Questionnaire for the Teacher of Psychology Teacher´s Conceptualizations and Beliefs was administered to 18 Tutors and 21 Co-Tutors, of "Special Didactic and Practices of Psychology Teaching". Figures of discoursive enunciation of Tutors and Co-tutors are built, with their thinking of what is taught and what is learnt and their analysis of what enables and what dificults the construction of Psychology Teacher´s role. Relevant outcomes about the worth of community of practice and their acknowledge of the tensions between Psychologist Profession and Psychology Teacher Profession.

Formadores de profesores de psicología, prácticas de enseñanza y construcción de saberes: cruzando fronteras entre escenarios y perspectivas diferentes / Teachers modelling psychology teachers, apprenticeship and knowledge construction: crossing the boundaries between different settings and perspectives

El trabajo analiza ideas explícitas e implícitas que construyen Formadores/ Tutores de Profesores de Psicología en Formación en Universidad de Buenos Aires. Unidad de Análisis: Modelos Mentales Situacionales de Intervención. Objetivo: identificar fortalezas y nudos críticos en la elaboración reflexiva de la Praxis Formativa del Profesorado en Educación Media y Superior. Estudio descriptivo y exploratorio con análisis cualitativos y cuantitativos. Comunidades de práctica y categorías de análisis del Enfoque Socio-Cultural (Vygotsky) y Teoría de la Actividad (Engestrõm) son re-contextualizadas, entramadas con investigación en Prácticas y Residencias (Terigi, Edelstein). Se administró Cuestionario sobre Situaciones Problema del Formador de Profesores de Psicología a 18 Tutores y 21 Co-tutores de Didáctica Especial y Prácticas de Enseñanza en Psicología y se aplicó Matriz Multidimensional de Análisis. Fortalezas: complejidad, historización, inter-agencialidad, pertinencia/especificidad, dilemas éticos. Nudos críticos: escasa investigación-intervención, destinatario unidireccional y sobre-implicación en Co-tutores. Construcción estratégica de tramas inter-agenciales y entrelazamientos inter-institucionales para aprendizaje expansivo profesional...

The suprachiasmatic nucleus is part of a neural feedback circuit adapting blood pressure response.

The suprachiasmatic nucleus (SCN) is typically considered our autonomous clock synchronizing behavior with physiological parameters such as blood pressure (BP), just transmitting time independent of physiology. Yet several studies show that the SCN is involved in the etiology of hypertension. Here, we demonstrate that the SCN is incorporated in a neuronal feedback circuit arising from the nucleus tractus solitarius (NTS), modulating cardiovascular reactivity. Tracer injections into the SCN of male Wistar rats revealed retrogradely filled neurons in the caudal NTS, where BP information is integrated. These NTS projections to the SCN were shown to be glutamatergic and to terminate in the ventrolateral part of the SCN where light information also enters. BP elevations not only induced increased neuronal activity as measured by c-Fos in the NTS but also in the SCN. Lesioning the caudal NTS prevented this activation. The increase of SCN neuronal activity by hypertensive stimuli suggested involvement of the SCN in counteracting BP elevations. Examining this possibility we observed that elevation of BP, induced by α1-agonist infusion, was more than twice the magnitude in SCN-lesioned animals as compared to in controls, indicating indeed an active involvement of the SCN in short-term BP regulation. We propose that the SCN receives BP information directly from the NTS enabling it to react to hemodynamic perturbations, suggesting the SCN to be part of a homeostatic circuit adapting BP response. We discuss how these findings could explain why lifestyle conditions violating signals of the biological clock may, in the long-term, result in cardiovascular disease.

Re-mediatizar la memoria social para aprender de la experiencia y construir futuro: perspectivas de agentes psicoeducativos sobre violencias en escuelas / Re-mediating the social memory for learning from the experience and building the future: perspectives of psycho-educational agents about violences at school

El trabajo presenta grupos de historización e intervención estratégica, construídos a partir de narrativas de agentes psicoeducativos sobre su práctica profesional con situaciones de violencias en escuelas. El objetivo es identificar estructuras de interacciones entre sujetos, problemas y prácticas en figuras de intervención, y analizar los sistemas representacionales que orientan la reflexión sobre la historia de la actividad, capitalizando experiencias colectivas en intervenciones estratégicas. Categorías de la Teoría de la Actividad fundamentan la conceptualización. Se administró el Cuestionario sobre Situaciones-Problema de Violencia en Escuelas a 130 agentes y se aplicó al análisis de datos la Matriz de Profesionalización Psicoeducativa. El análisis factorial evidencia confiabilidad de instrumentos de recolección de datos e identifica sistemas representacionales de figuras y grupos. Se hallan fracturas de la memoria social y desafíos para la intervención estratégica, con significativas diferencias entre los cuatro grupos construídos. Se abren líneas de indagación sobre “aprendizaje expansivo” en contextos educativos.

Re-mediatizar la memoria social para aprender de la experiencia y construir futuro: perspectivas de agentes psicoeducativos sobre violencias en escuelas / Re-mediating the social memory for learning from the experience and building the future: perspectives of psycho-educational agents about violences at school

El trabajo presenta grupos de historización e intervención estratégica, construídos a partir de narrativas de agentes psicoeducativos sobre su práctica profesional con situaciones de violencias en escuelas. El objetivo es identificar estructuras de interacciones entre sujetos, problemas y prácticas en figuras de intervención, y analizar los sistemas representacionales que orientan la reflexión sobre la historia de la actividad, capitalizando experiencias colectivas en intervenciones estratégicas. Categorías de la Teoría de la Actividad fundamentan la conceptualización. Se administró el Cuestionario sobre Situaciones-Problema de Violencia en Escuelas a 130 agentes y se aplicó al análisis de datos la Matriz de Profesionalización Psicoeducativa. El análisis factorial evidencia confiabilidad de instrumentos de recolección de datos e identifica sistemas representacionales de figuras y grupos. Se hallan fracturas de la memoria social y desafíos para la intervención estratégica, con significativas diferencias entre los cuatro grupos construídos. Se abren líneas de indagación sobre ôaprendizaje expansivoö en contextos educativos.(AU)

Conversion of high and low pollen protein diets into protein in worker honey bees (Hymenoptera: Apidae).

Adequate protein levels are necessary to maintain strong honey bee [Apis mellifera (L.)] colonies. The aim of this study was to quantify how pollens with different crude protein contents influence protein stores within individual honey bees. Caged bees were fed one of three diets, consisting of high-protein-content pollen, low-protein-content pollen, or protein-free diet as control; measurements were made based on protein content in hemolymph and fat body, fat body weight, and body weight. Vitellogenin in hemolymph was also measured. Bees fed with high crude protein diet had significantly higher levels of protein in hemolymph and fat bodies. Caged bees did not increase pollen consumption to compensate for the lower protein in the diet, and ingesting approximately 4 mg of protein per bee could achieve levels of 20 microg/microl protein in hemolymph. Worker bees fed with low crude protein diet took more time in reaching similar protein content of the bees that were fed with high crude protein diet. The data showed that fat bodies and body weight were not efficient methods of measuring the protein status of bees. The determination of total protein or vitellogenin concentration in the hemolymph from 13-d-old bees and protein concentration of fat bodies from 9-d-old bees could be good indicators of nutritional status of honey bees.

The NPY intergeniculate leaflet projections to the suprachiasmatic nucleus transmit metabolic conditions.

The intergeniculate leaflet (IGL) is classically known as the area of the Thalamic Lateral Geniculate Complex providing the suprachiasmatic nucleus (SCN) non-photic information. In the present study we investigated whether this information might be related to the metabolic state of the animal. The following groups of male Wistar rats were used for analysis of neuropeptide Y (NPY) and c-Fos in the IGL and SCN. (1) Fed ad libitum. (2) Fasted for 48 h. (3) Fasted for 48 h followed by refeeding for 3 h. (4) Monosodium glutamate-lesioned and 48 h fasted. (5) Electrolytic lesion in the IGL and 48 h fasted. The results were quantified by optical densitometry. Neuronal tracers were injected in two brain areas that receive metabolic information from the periphery, the arcuate nucleus (ARC) and Nucleus of the Tractus Solitarius to investigate whether there is an anatomical relationship with the IGL. Lesion studies showed the IGL, and not the ARC, as origin of most NPY projections to the SCN. Fasting induced important changes in the NPY expression in the IGL, coinciding with similar changes of NPY/glutamate decarboxylase projections of the IGL to the SCN. These changes revealed that the IGL is involved in the transmission of metabolic information to the SCN. In fasted animals IGL lesion resulted in a significant increase of c-Fos in the SCN as compared to intact fasted animals demonstrating the inhibitory influence of the IGL to the SCN in fasting conditions. When the animal after fasting was refed, an increase of c-Fos in the SCN indicated a removal of this inhibitory input. Together these observations show that in addition to increased inhibitory IGL input during fasting, the negative metabolic condition also results in increased excitatory input to the SCN via other pathways. Consequently the present observations show that at least part of the non-photic input to the SCN, arising from the IGL contains information about metabolic conditions.

Selection and estimation of the heritability of sunflower (Helianthus annuus) pollen collection behavior in Apis mellifera colonies.

We selected honey bee colonies (Apis mellifera L.) with a high tendency to collect sunflower pollen and estimated the heritability of this trait. The percentage of sunflower pollen collected by 74 colonies was evaluated. Five colonies that collected the highest percentages of sunflower pollen were selected. Nineteen colonies headed by daughters of these selected queens were evaluated for this characteristic in comparison with 20 control (unselected) colonies. The variation for the proportion of sunflower pollen was greater among colonies of the control group than among these selected daughter colonies. The estimated heritability was 0.26 +/- 0.23, demonstrating that selection to increase sunflower pollen collection is feasible. Such selected colonies could be used to improve sunflower pollination in commercial fields.

Mitochondrial DNA haplogroups in Amerindian populations from the Gran Chaco.

Mitochondrial DNA from 141 individuals was typed for diagnostic restriction sites and the 9-bp region V deletion to examine the distribution of the founding mtDNA lineage haplotypes in three Amerindian populations (Mataco, Toba, and Pilagá) who currently inhabit the Argentinian part of the Gran Chaco. All four lineages were identified in the three tribes and four population samples studied. Disregarding ethnic or geographic origin, haplogroups B and D exhibit high incidence among the Gran Chaco inhabitants, whereas haplogroups A and C are present in a lower frequency. Three individuals possess none of the characteristic markers and, therefore, could not be assigned to one of those lineages. A neighbor-joining representation of F(ST) distances reflects the current geographic location of the populations, and this also corresponds to their historic distribution. After separating South America into four major regions (Tropical Forest, Andes, Gran Chaco, and Patagonia-Tierra del Fuego), the Gran Chaco populations present the highest average intragroup variability (Hs = 0.64) as well as the lowest intergroup diversity (G(')(ST) = 0.06). These findings suggest high levels of gene flow among the Chaco tribes, as well as with neighbor populations from outside the region.

Africanized honey bees (Hymenoptera: Apidae) have a greater fidelity to sunflowers than European bees.

A study of sunflower, Helianthus annuus L., pollen collection by Africanized and European honey bees, Apis mellifera L., was conducted in a hybrid seed production field in Argentina. Africanized honey bees collected significantly larger proportions of sunflower pollen than did European honey bees. The result suggests that Africanized bees would be more efficient for commercial sunflower seed production.

nef/long terminal repeat quasispecies from HIV type 1-infected Mexican patients with different progression patterns and their pathogenesis in hu-PBL-SCID mice.

To examine the genetic features of the long terminal repeat (LTR) derived from six HIV-1-infected individuals enrolled in the Mexico City Cohort, we cloned and sequenced a 505-bp fragment of the proviral LTR from their peripheral blood mononuclear cells (PBMCs). All patients harbored HIV-1 LTR quasispecies corresponding to the B subtype. Three patients with high CD4+ T cell counts (>500/mm3) presented LTR sequences with point mutations in the TAR bulge. The LTR sequence from a patient classified as a long-term nonprogressor (LTNP) presented the most frequent naturally occurring length polymorphism (MFNLP) and two substitutions in the TAR region that were predicted to result in two alternative secondary RNA structures. A novel 18-bp deletion, which eliminates part of the putative binding site for the nuclear factor of activated T cells (NFAT-1), was identified in the overlapping nef/LTR sequence derived from a patient progressing to AIDS. This deletion coincides with the ability of this virus to consistently replicate at low levels in vivo (viral load <500 RNA copies/ml) and in vitro (unsuccessful virus isolation). On one occasion, when virus isolation was successful, the 18-bp deletion was no longer evident and LTR sequences with intact NFAT-1-binding sites were observed. Inoculation of hu-PBL-SCID mice with viruses from several Mexican patients resulted in differential CD4+ T cell depletion patterns 15 days postinfection, which agree with the in vivo CD4+ T cell count data from each patient.

[Seroprevalence of infection by St. Louis encephalitis virus in the Province of Formosa]. / Seroprevalencia de infección por el virus encefalitis San Luis en la Provincia de Formosa.

The aim of this work was to determine the prevalence of antibodies against St. Louis encephalitis virus (SLE) in human sera provided by the Laboratory of Epidemiological Surveillance from Formosa District (Province of Formosa, Argentina) in 1995 and 1997. The tests used for this study were hemagglutination inhibition (HI) and neutralization (NT). The screening performed by NT test showed prevalences of 21% (60/284) and 32% (50/157) of antibodies in samples obtained in 1995 and 1997 respectively. In 1995, 14% of tested sera showed low titer of neutralizing antibodies (NT) (1/20 and 1/40) whereas in 1997, 19% of the sera presented titers of NT antibodies equal or greater than 1/80. It was observed that sera with low titers of NT antibodies (1/20-1/40) resulted negative in HI in the simultaneous titration of antibodies by NT and HI whereas other sera presented high titers for both tests. This relation between the low and the high titers of antibodies indicates the presence of past and recent infections and the continuous circulation of this virus. Moreover, the prevalence of NT antibodies in the surveyed population increased significantly in 2 years (p < 0.0075) confirming the endemicity of this agent in this area and showing the need to perform studies of non-confirmed viral etiology febrile diseases to determine its importance in human pathogenicity.

Seroprevalencia de infección por el virus encefalitis San Luis en la Provincia de Formosa. / [Seroprevalence of infection by St. Louis encephalitis virus in the Province of Formosa]

The aim of this work was to determine the prevalence of antibodies against St. Louis encephalitis virus (SLE) in human sera provided by the Laboratory of Epidemiological Surveillance from Formosa District (Province of Formosa, Argentina) in 1995 and 1997. The tests used for this study were hemagglutination inhibition (HI) and neutralization (NT). The screening performed by NT test showed prevalences of 21

(60/284) and 32

(50/157) of antibodies in samples obtained in 1995 and 1997 respectively. In 1995, 14

of tested sera showed low titer of neutralizing antibodies (NT) (1/20 and 1/40) whereas in 1997, 19

of the sera presented titers of NT antibodies equal or greater than 1/80. It was observed that sera with low titers of NT antibodies (1/20-1/40) resulted negative in HI in the simultaneous titration of antibodies by NT and HI whereas other sera presented high titers for both tests. This relation between the low and the high titers of antibodies indicates the presence of past and recent infections and the continuous circulation of this virus. Moreover, the prevalence of NT antibodies in the surveyed population increased significantly in 2 years (p < 0.0075) confirming the endemicity of this agent in this area and showing the need to perform studies of non-confirmed viral etiology febrile diseases to determine its importance in human pathogenicity.

Apolipoprotein B signal peptide polymorphism distribution among south Amerindian populations.

We report the distribution of the APOB signal peptide polymorphism in 5 native populations of South America: 2 samples of Mataco and 1 sample each of Pilagá and Toba from the Argentinian Chaco and 1 sample of Ache from the Paraguay forest. A randomly selected subsample of a previously studied sample from the Cayapa of Ecuador (Scacchi et al. 1997) was reanalyzed to investigate probable differences attributable to sampling, laboratory techniques, or interobserver error. The polymorphism observed in the signal peptide region of the APOB gene among native populations of South America exhibits the same range of variation found among geographic continental populations, confirming the high genetic heterogeneity of South Amerindians. Extremes in the allele prevalences were found among the Mataco and Ache, populations not far apart geographically. The small differences in genotype and allele frequencies between the subsample of the Cayapa analyzed here and the original Cayapa sample and between the 2 Mataco samples were not statistically significant and most likely were due to sampling error.

Seroepidemiological and molecular studies of human T cell lymphotropic virus type II, subtype b, in isolated groups of Mataco and Toba Indians of northern Argentina.

We studied plasma samples from 2082 Mataco Indians living in 22 different communities in the western part of Formosa Province, northern Argentina. Samples were screened for HTLV-I/II antibodies by particle agglutination assay. All positive or borderline samples were then tested by an immunofluorescence assay (IFA) on C19 HTLV-II-producing cells. Western blot was used for confirmation of all IFA-positive plasma samples. The crude HTLV-II seroprevalence was 3.0% (62 of 2051), and 0.9% (5 of 588) in children less than 10 years old. The latter result suggests ongoing mother-to-child transmission, probably by breast feeding. There was a marked increase in HTLV-II seroprevalence with age (0.9%, 0-10 years; 1.6%, 11-20 years; 4.4%, 21-30 years; 3.4%, 31-40 years; 7.2%, 41-50 years; 5.7%, >50 years) in both male (p = 0.002) and female subjects (p = 0.00002). None of the 80 non-Indian inhabitants tested was HTLV-I/II seropositive. In a second study, among 105 Toba Indians from a village (Primavera) of the eastern part of this region, 23 were HTLV-II seropositive with a seroprevalence of 59% in those more than 40 years old. From seven of the Indians from Primavera, three others from neighboring regions (including two Tobas and one Pilaga), and one intravenous drug user (IVDU) from Rosario, DNA was extracted from peripheral blood mononuclear cells, and the gp21 transmembrane-encoding gene (590 bp) was amplified by PCR, cloned, and sequenced. LTR sequences were also obtained from the Pilaga, the IVDU, and one Toba. Molecular and phylogenetic analyses revealed that the Indians were all infected with closely related HTLV-II molecular strains belonging to the b subtype, while the IVDU was infected with an HTLV-II subtype a variant. Such data help to make a phylogenetic atlas of HTLV-II among Amerindian tribes and are crucial to gain new insights into the origin and modes of dissemination of this human retrovirus in the Americas.

Prevalencia de anticuerpos contra flavivirus en jóvenes voluntarios ingresantes al servicio militar de la Provincia de Formosa, Argentina / Seropositive against Flavivirus in young recruits from the Province of Formosa, Argentina

El objetivo del presente trabajo fue conocer la prevalencia de anticuerpos en poblaciones de riesgo a los Flavivirus. Se analizaron 189 sueros humanos provenientes de 3 localidades de la Provincia de Formosa. La región estudiada fue seleccionada por su proximidad a Brasil y Paraguay con el fin de verificar la probable introducción de Flavivirus de estos pa1ses, especialmente dengue y fiebre amarilla o la emergencia de los ya existentes en nuestro país. Se realizaron las pruebas de inhibición de la hemoaglutinación (IH), fijación del Complemento (FC) y neutralización (NT), utilizando los virus de la encefalitis de San Luis (ESL), Bussuquara, Ilheus, fiebre amarilla (FA)y dengue subtipos 1 y 2. Todos los sueros fueron negativos por IH para dengue e Ilheus. Por esta prueba un suero fue positivo sólo para FA, y dos sólo para Bussuquara, confirmándose uno por NT. Un total de 22 sueros fue positivo para ESL por IH y 40 sueros reaccionaron por la prueba de NT contra el mismo virus. La prevalencia de anticuerpos IH y NT fue similar para las tres localidades estudiadas. Estos resultados muestran que el virus ESL circula efectivamente en la zona estudiada con un valor de prevalencia de anticuerpos IH y NT significativo y que el mencionado virus podría cumplir un rol importante en infecciones febriles de etiología viral no confirmados en esa zona de nuestro país(AU)

Prevalencia de anticuerpos contra flavivirus en jóvenes voluntarios ingresantes al servicio militar de la Provincia de Formosa, Argentina / Seropositive against Flavivirus in young recruits from the Province of Formosa, Argentina

El objetivo del presente trabajo fue conocer la prevalencia de anticuerpos en poblaciones de riesgo a los Flavivirus. Se analizaron 189 sueros humanos provenientes de 3 localidades de la Provincia de Formosa. La región estudiada fue seleccionada por su proximidad a Brasil y Paraguay con el fin de verificar la probable introducción de Flavivirus de estos pa1ses, especialmente dengue y fiebre amarilla o la emergencia de los ya existentes en nuestro país. Se realizaron las pruebas de inhibición de la hemoaglutinación (IH), fijación del Complemento (FC) y neutralización (NT), utilizando los virus de la encefalitis de San Luis (ESL), Bussuquara, Ilheus, fiebre amarilla (FA)y dengue subtipos 1 y 2. Todos los sueros fueron negativos por IH para dengue e Ilheus. Por esta prueba un suero fue positivo sólo para FA, y dos sólo para Bussuquara, confirmándose uno por NT. Un total de 22 sueros fue positivo para ESL por IH y 40 sueros reaccionaron por la prueba de NT contra el mismo virus. La prevalencia de anticuerpos IH y NT fue similar para las tres localidades estudiadas. Estos resultados muestran que el virus ESL circula efectivamente en la zona estudiada con un valor de prevalencia de anticuerpos IH y NT significativo y que el mencionado virus podría cumplir un rol importante en infecciones febriles de etiología viral no confirmados en esa zona de nuestro país

[Prevalence of Flavivirus antibodies in young voluntary recruits to military service in the province of Formosa, Argentina]. / Prevalencia de anticuerpos contra flavivirus en jóvenes voluntarios ingresantes al servicio militar de la Provincia de Formosa, Argentina.

The aim of the present study was to investigate the seroprevalence to Flavivirus, in young people living in risk areas. We analyzed 189 human sera from 3 towns in the Province of Formosa. This area corresponds to the border that limits Brasil and Paraguay and the aim was to search for a possible introduction of Dengue and Yellow Fever from these countries. Serological tests such as haemagglutination inhibition (HI), complement fixation (CF) and neutralization (NT) were performed using St. Louis encephalitis (SLE), Bussuquara, Ilheus, Yellow fever and dengue 1 and 2 viruses. No definite evidence for HI antibodies to dengue and Ilheus was obtained. One serum cross-reacted only with yellow fever and two sera only for Bussuquara by the HI test. Only one serum was confirmed to be positive for Bussuquara by NT test. A total of 22 sera from 189 were positive for SLE by the HI test and 40 were also reactive by the NT test. The seroprevalence measured by HI and NT antibodies was similar in the three departments studied. These results show that SLE virus is present in the North of Argentina with an important value of prevalence so that this agent could play an important role in the febrile infections not virologically confirmed.