Background: The aim of the present study was to compare the performance of a commercial real-time PCR (RT-PCR) assay, a characterized in house approach and an enzyme immunoassay (EIA) on set of stool samples from patients with suspected Clostridium difficile infection (CDI) during the period January-May 2017. Methods & Materials: A total of 97 consecutive feces samples were obtained from hospitalized patients with suspected CDI. All specimens were processed as follows: 1) culture in anaerobic atmosphere on CHROMagar™C.difficille medium. Colonies suspected to be C. difficile were confirmed by MALDI-TOF (Bruker). Toxin production was tested by EIA and PCR 2) EIA using kit C.Diff-Quick-Check-Complete for the detection of glutamate dehydrogenase (GDH), toxin (Tx) A and B 3) RT-PCR using the LightCycler. This PCR detect the presence of the tcdC gene, as well as the 18-bp deletions which have been associated with the "epidemic strain" ribotype 027 4)"in-house" PCR targeting the C. difficile toxin gene tcdB. Results: Toxigenic C. difficile was isolated in 14 of the 97 specimens (14,4%). The RT-PCR and "in-house" PCR had a concordance of 92,9% (13/14) and 100% (14/14) with toxigenic culture, respectively. 18 bp deletions in the tcdC gene were detected in 2 of the 13 positive samples using RT-PCR by melting curve analysis. Six samples were positive for GDH and Tx (Ag + Tx+), "in-house" PCR and toxigenic culture. Of 15 positive GDH and negative Tx (Ag + Tx-), 7 were positive by both PCRs and toxigenic culture. Non-toxigenic C. difficile was isolated in 8 samples (Ag + Tx-) and negative PCR. All specimens which were negative by culture were also negative by PCR. Using toxigenic culture as the "gold standard", the sensitivities, specificities, and positive and negative predictive values, respectively, of the assays were 42,9%, 90,4%, 42,9%, and 90,4% for the EIA; 92,9%, 100%, 100%, and 98,8% for the RT-PCR; and 100%, 100%, 100%, and 100% for the "in-house" PCR. Conclusion: According to results, the molecular methods have an sensitivity and specificity higher than the EAI. Nevertheless, EIAs are still very useful for screening due to the high negative predictive value. For inconclusive results (Ag + Tx-) we recommend performing a molecular method.

Background: Acute respiratory infections (ARI) are a leading cause of morbidity and mortality worldwide. There is a need to demonstrate the clinical impact of using the new, rapid and sensitive molecular assays in prospectively designed studies. Objectives: To study the impact on medical management of a rapid molecular assay in patients with respiratory infections. Study design: A prospective, randomized, non-blinded study was performed in patients presenting to the Emergency Department during two respiratory seasons (2016-2017). Diagnosis was performed by FilmArray Respiratory Panel (FilmArray-RP) or by immunofluorescence assay (IFA). Results: A total of 432 patients (156 children and 276 adults) were analyzed. Diagnosis with FilmArray-RP was associated with significant changes in medical management including withholding antibiotic prescriptions (OR: 15.52, 95% CI: 1.99-120.83 in adults and OR: 12.23, 95% CI: 1.56-96.09 in children), and reduction in complementary studies in children (OR: 9.64, 95% CI: 2.13-43.63) compared to IFA. Decrease in oseltamivir prescriptions was significantly higher in adults in the FilmArray-RP group (p= 0.042; OR: 1.19, 95% CI: 0.512.79) compared to adults managed with IFA. Diagnostic yield was significantly higher by FilmArray-RP (81%) than by IFA (31%)(p < 0.001). The median time from sample collection to reporting was 1 h 52 min by FilmArray-RP and 26 h by IFA (p < 0.001). Conclusions: The high respiratory viruses' detection rate and availability of results within two hours when using FilmArray-RP were associated with decreases in antibiotic prescriptions and complementary studies and more accurate use of oseltamivir.

Background: Influenza A and B (Flu A/B), parainfluenza (PIV) and respiratory syncytial virus (RSV) cause lower and upper respiratory tract disease (LRD-URD) with significant clinical impact on patients with hematological malignancies (HM) or hematopoietic stem cell transplantation (HSCT). Rhinoviruses (HRV) are being increasingly detected in these infections, although their clinical impact remains a matter of debate. Our objective was to describe and compare clinical characteristics and outcomes of patients with HM and HSCT with LRD-URD caused by HRV versus non-HRV: Flu A/B, PIV and RSV. Methods & Materials: Prospective observational study. We compared HRV (G1) vs. Flu A/B, PIV and RSV (G2) respiratory infections in patients with HM and HSCT between January 2013 and September 2017. Chi-square analysis and Kruskal-Wallis test were used for categorical and continuous variables, respectively. Results: We enrolled 114 episodes: 45 in G1, 69 in G2. Both groups had patients with similar hematological diseases and stages, being lymphoma and acute leukemia the most frequent. Steroid therapy (20% vs 50.7%, p = 0.001) was significantly higher in G2, while use of biologic agents (40% vs 17.4%, p = 0.007), lymphopenia (33% vs 16.2% p = 0.034) and clinical presentation during preengraftment (20% vs 5.8%, p = 0.032) was higher in G1. Rhinorrhea was the most common symptom in G1 (71.1% vs 46.4%, p = 0.009). Other symptoms had similar frequencies in both groups. Over 50% of all infections presented as LRD (52% vs 50.7%, p = 0.968). Hypoxemia presented in similar rates (28.9% vs 27.5%, p = 0.875). The most common tomographic infiltrates were alveolar pattern and bilateral extension. In G1, co-pathogens in respiratory specimens were isolated in three patients (6.7% vs 0% p = 0.053) and other three had detectable plasma CMV viral load (6.7% vs 0% p = 0.012). Hospitalization was required in 58.8% of cases, with no significant difference between both groups. The 30-day overall mortality rate due to G1 and G2 infections were 6.7% and 7.2%, respectively (p = 1). Conclusion: Patients with HM or HSCT and HRV infections had similar clinical picture and outcome to common respiratory viruses, with significant morbidity. Therefore, active diagnostic approaches are required, especially in patients with lymphopenia or use of biologic agents.

Abstract Biodiversity management in exploratory projects, especially in remote areas, includes risk analysis and decision-making with little information available. In order to optimize the effort and manage business risks, biodiversity information from previous studies and secondary sources and recent data resulting from field work of the companies should be considered valuable (e.g. biodiversity and environmental impact studies). The objective of this project was to create a biodiversity information system enabling the effective resources management as well as activities planning, through an understanding of the different attributes in the landscape and the ecosystem services analysis, integrating the multidisciplinary knowledge within the framework of a spatial analysis. Biodiversity information can be organized for developing biodiversity conservation strategies and for managing oil and gas projects' life-cycle, as long as it is available and logically structured. Biodiversity data is usually in reports where its consolidation and management is not easy. Geographic Information Systems rise an opportunity; geospatial data (georeferenced information) can be converted in a digital format and the management improved. For this case study, we selected the variables needed to be included in the biodiversity database, reviewing the quality of the data, its usefulness for a potential future use, the availability, versatility of biodiversity consultations and the data generation costs and in the right time. The conceptualization and structure of the biodiversity geodatabase developed in this project allows the integration and spatial analysis of biological, social, environmental and engineering information of exploratory projects, becoming an important tool to answer questions and solve problems. With the aim of speeding up the analysis and the subsequent use or interpretation, important considerations for the data standardization and systematization were addressed from participatory workshops with different disciplines (as engineering, community relations, and safety and environment). This database helps data management improvement and gap analysis as well as biodiversity data adquisition in Oil & Gas projects. This tool contributes to energy companies in the selection of biodiversity and ecosystem services performance indicators; as well as their subsequent monitoring and the implementation of biodiversity actions plans.

Abstract Tropical forests are megadiverse ecosystems with a high degree of complexity. Inside them, may be recognized areas where the important resources are concentrated for populations of wild fauna inhabiting them. Those areas called BSA (biological sensitive areas) attract a great quantity and diversity of species, and include among others, the salt and clay licks, baths/watering holes, feeders and nesting zones. During the activities of seismic 3D, are established mitigation measures such as offset displacements applied near the BSAs; and although these management practices are divulged, currently there is scarce information regarding the efficiency of these; as well as the effects of the seismic on the wild fauna population. The necessity of extending the knowledge there is on these aspects is the basis of the importance of this work. The study consisted in the follow up through the use of trap cameras of a population of Leopardus pardalis (ocelot) using as biological indicators: abundance and spacial distribution of the specie, and also the monitoring of the frequency of use of five SBAs (two salt or clay licks, two roads and a watering hole), which were selected according to their size, frequency of use and distance from the seismic lines. The studied area had a scope of approximately 35,8 Km2, inside the zone of 3D seismic acquisition (210 Km2); in this zone was distributed a grid with 23 stations with trap cameras (separated with a distance between 900 -1300 m), as well as 5 stations in the BSAs selected. The trap cameras were located at a height between 25-45cm, operating 24 hours and being reviewed in average every 10 days. The study period include the phases: before (control), during (phases of topography, drilling and registry), and after the seismic activity (abandonment). The data obtained applies to the minimization of impacts on the biodiversity in 3D seismic explorations, serving as support to improve environmental practices of the sector as well as the main aspects to be taken into consideration for success. The resulting information also contributes to the knowledge of the biological diversity of one of the most remote zones and with high exploration and production of hydrocarbons activities.

Abstract For more than twenty years, Seismic surveys have been changing both in the incorporation of environmental and biodiversity criteria as well as in its implementation and performance indicators. The 3D seismic survey in the block 57 located in the tropical Andes, lower basin of the Urubamba river, has incorporated new techniques to minimize direct, secondary and cumulative impacts, focusing on each phase of the exploratory project. The technology used for data acquisition was made through the Geospace Seismic Recorder (GSX), which is a cableless seismic acquisition system that does not need a white house in seismic lines. This made possible the reduction of flying hours to transport materials, as well as a lower fuel consumption and clearing areas of flying camps and drop zones. The effluent treatment was one of the greatest challenges, due to the environmental standards set for dumping. In the base camp, additionally to the implementation of a wastewater treatment plant(conventionally used in other projects), it was necessary to complement it with previous processes by the use of equalization tanks and with subsequent processes using sedimentation cameras, flocculation and high rate filtration. During the topography and advanced studies, each group was assistedwith specialized personnel for the identification of Biologically Sensitive Areas (BSA) as well as forest survey prior to deforestation. In spite of the difficulty of the terrain and the predominance of the bamboo (Guadua spp.), seismic lines had a maximum width of 1.5 meters andrespected trees of more than 10 cm DBH. Biologically Sensitive Areas (BSA) were identified and avoided in the flying camps, heliports, seismics lines and drop zones. Abandonment activities considered primarily the natural regeneration of the forest. Residual wood from deforestation and flying camps were chopped on average of 0.3 × 0.45 × 0.20 meters in order to promote its decomposition. In addition, compacted soil was loosed on the areas intervened. The use of similar species that were reported in the forestry survey was also considered. For this purpose a greenhouse with 230 seedlings on average was installed in each camp from the beginning until the abandonment, and certified seed of native forest species: Amasisa (Erythrina ulei), Huairuro (Ormosia coccinea), Pachaco (Parkia multijuga), Bolaina (Guazuma crinita) Copaiba (Copaifera paupera) was also used. In the case of drop zones located in lines nearby, samples were used to the area.

Abstract Biological monitoring programs provide data and information for decision making and to ensure the resources protection. However, in tropical ecosystems that are home to most of the planet's biodiversity these programs need to be improved in design and implementation. As part of the Environmental Management Plan "Environmental Impact Assessment for the 2D-3D Seismic Program and drilling of 22 exploratory wells in Kinteroni, Mapi and Mashira – Block 57" (Peru), we develop a Biological Monitoring Plan to keep track of potential biological changes (temporal and spatial scale) caused by the project activities to identify the need for corrective actions or to define new measures for unforeseen impacts. Temporarily, the activities of the monitoring plan depend on the stages of the project (construction, operation and closure), meanwhile they correspond spatially to factors that may cause effects on the flora and fauna. Block 57 is located in the Amazon rain forest of southern Peru; this is an ecosystem with limited information. Seeking a scheme to support exploration activities, It has been designed a systematic biological monitoring program, based on a gradient of disturbance caused by the clarification of an area. This design is intended to identify the variables that are most sensitive to the effect of exploration activities in forests with similar features and comparable seasons. The design is being implemented in exploratory platforms of Block 57 located in the buffer zones of the Ashaninka and Machiguenga Communal Reserves and Otishi National Park, covering the three stages of the drilling process, and evaluating spatially flora and arthropods to smaller scale (≤ 150 m from the edge of the deforested area) and birds, small mammals and reptiles at the mesoscale (≤ 600 m from the edge of the deforested area), in the area around the cleared area. The information generated, besides determining the parameters used to assess the level of impacts on local wildlife generated during the drilling, helps to evaluate the effectiveness of appropriate sampling methodologies and optimizes logistics; looking forward to replicate this design in other tropical ecosystems.

Abstract The development of gas transportation projects is considered as one of the main causes of the loss of biodiversity, habitat fragmentation and edge effect. This study has important implications in terms of conservation, forest regeneration and wildlife management.The biological monitoring methodology was designed and implemented for linear projects such as identification criteria considering borders, functional food webs and transversal adaptive management approach to the different stages of a development project (construction, operation and closure) allowing the biological monitoring program of the "Environmental Impact Assessment (EIA) for the development of the southern Kinteroni field area "(Peru) evolve through these stages and function as a management tool and as a support for the various planning entities involved in the development of linear projects in tropical forest. The identification of the distances between the edge zones, intermediate and deep forest was conducted by measuring the intensity of light, allowing adjusting the model by the different characteristics of the forest. Wildlife records were made using camera traps.

Respiratory Syncytial Virus (RSV) has two major antigenic groups, A and B. The implications of these variants in the epidemiology and pathogenesis of RSV infection are not well defined. This study was undertaken to compare the two RSV subgroups in patients admitted to hospital. Clinical and epidemiologic features of RSV subgroups in children under 30 months of age with proven RSV acute lower respiratory infections were examined during 4 winters from 1993 to 1996 in Santa Fe, Argentina. RSV typing was carried out with monoclonal antibodies in nasopharyngeal cells by indirect immunofluorescence. Of the 177 RSV positive nasopharyngeal aspirates obtained from 1993 to 1996, 85 (48%) were available for typing. Seventy-three (85.9%) specimens were identified as Subgroup A and 12 (14.1%) as Subgroup B. Except in 1993, in which only Subgroup A was detected, both variants circulated throughout the epidemic season. Subgroup A infections produced more severe disease than Subgroup B infections, as assessed by the length of the hospital stay and the use of respiratory support. This difference was age related, being evident in infants 0-6 months old. Patients with Subgroup B infections were also significantly less frequently breast-fed (95% vs. 75% for A and B subgroups, respectively; P = 0.04). It is concluded that the severity of disease in Argentinian patients admitted with acute RSV infections may be associated with Subgroup A strains as determined by a serogrouping method.

The frequency of respiratory syncytial virus (RSV) and the distribution of subgroups A and B strains during 7 consecutive years (1990-1996) were examined in two cities of Argentina. Nasopharyngeal aspirates from 1,304 children less than 2 years of age hospitalized with acute lower respiratory infection were studied by indirect immunofluorescence. RSV was detected in 352 cases (26.9%), and the peak activity was observed in midwinter. Subgroup characterization was performed with two monoclonal antibodies against the F protein on nasopharyngeal aspirate smears. Of 195 samples, 174 (89.2%) were identified as subgroup A strains and 21 (10.8%) as subgroup B. Both strains cocirculated during 5 of 7 years studied with subgroup A predominating. Subgroup A occurred at least 8 times as often in all years except for 1994-1995. Children infected by subgroup A were younger than those infected by subgroup B (P < 0.05). The association of subgroup A infection with bronchiolitis and subgroup B with pneumonia was statistically significant (P < 0.03).

Background: Adenoviruses are the second cause of acute lower respiratory infection (ALRI) of viral origin in small children from Buenos Aires, Argentina. Objective: The aim of this study was to characterize, by restriction enzyme analysis, 17 adenovirus strains isolated from the nasopharyngeal aspirates of children under 2 years of age hospitalized due to ALRI. Study design: Seventeen adenovirus strains isolated between May 1991 and December 1992 in one hospital of Buenos Aires were studied. Adenoviruses were amplified in HEp-2 cells and viral DNA was studied with the restriction enzymes Bam HI and Sma I. Results and conclusions: Eighty two percent (14/17) of the isolates were classified as adenoviruses from subgenus b and 17.7% (3/17) belonged to subgenus c. Genome type 7 h was detected in 85.7% (12/14) and 7 i in 14.3% (2/14) of the strains from subgenus b. The case lethality associated with adenovirus genome type 7 was 28.6% (4/14 cases). Three fatal cases corresponded to Ad 7 h and one to Ad 7i. Ad 7h shows a high prevalence in small children hospitalized with ALRI and is associated with a high fatality rate.

Background: Acute lower respiratory infection (ALRI) is one of the main causes of morbidity and mortality in small children. Objective: The aim of this study was to determine the frequency, seasonality and association with clinical entities of respiratory syncytial virus (RSV) and adenoviruses in children with ALRI. Study design: During 2 consecutive years (1991–1992), 168 children under 2 years of age hospitalized due to ALRI in a public pediatric hospital of Buenos Aires, Argentina, were studied. RSV and adenoviruses were investigated on nasopharyngeal aspirates (NPA) by indirect immunofluorescence (IIF). HEp-2 cells were used for adenovirus isolation. Results: RSV was detected in 36.3% and adenoviruses in 14.3% of the cases (P<0.0001). All adenoviruses detected by IIF were also isolated in culture. Out of 61 RSV cases, 57% corresponded to bronchiolitis and 43% to pneumonia. Ninety-two per cent of children with RSV were less than 1 year old and 70% were less than 5 months. The highest number of RSV cases were observed during winter, with a clear peak in July. Seventy-one per cent of adenovirus cases were associated with pneumonia and only 24% with bronchiolitis (P<0.02), and predominated in children older than 5 months of age (P<0.0001). Adenoviruses were detected in almost all months of the year with a small peak at the end of winter and beginning of spring. No significant differences in clinical features at admission, breast feeding or malnutrition were observed among children with RSV or adenovirus diagnosis versus those with no viral etiology. The overall fatality rate was 2.4%. In all fatal cases adenovirus was detected in NPA. Thus, fatality rate among patients with adenoviruses reached 16.7%. Conclusions: Our findings show the importance of RSV and adenoviruses associated with ALRI in hospitalized children under 2 years of age and the different epidemiological patterns of the two viruses in Buenos Aires, Argentina.

In order to determine the importance of Chlamydia trachomatis in infertility due to tubal occlusion, the prevalence of C. trachomatis antibody was studied in two populations of Argentine women, pregnant and infertile with tubal occlusion. IgG and IgM against C. trachomatis were determined by indirect immunofluorescence in McCoy cells infected with strain L2Bu434 of C. trachomatis. In infertile women, specific anti-C. trachomatis IgM was detected in 5 out of 32 (15,6%) and IgG in 20 out of 32 (75%). In pregnant women, specific IgM was detected in 4,8% (4/83) and IgG in 20,5% (17/83). The frequency of IgG detection was significantly higher in infertile than in pregnant women (p < 0.000). Thirteen out of 20 (65%) women who underwent laparoscopic examination had evidence of chronic inflammatory disease described as yellowish viscous cysts resembling "frog eggs" in Douglas, utero and/or perihepatitis. Twelve out of fourteen (86%) infertile women with positive serology for C. trachomatis presented one or more of these laparoscopic findings. C. trachomatis antigen was detected in 2 out of 10 tubal biopsies by direct immunofluorescence with monoclonal antibodies although isolation in McCoy cells was negative. Our results show the importance of C. trachomatis in infertility due to tubal occlusion and the need of C. trachomatis diagnosis in routine gynecologic analysis to prevent infertility and neonatal infection.

In order to determine the importance of Chlamydia trachomatis in infertility due to tubal occlusion, the prevalence of C. trachomatis antibody was studied in two populations of Argentine women, pregnant and infertile with tubal occlusion. IgG and IgM against C. trachomatis were determined by indirect immunofluorescence in McCoy cells infected with strain L2Bu434 of C. trachomatis. In infertile women, specific anti-C. trachomatis IgM was detected in 5 out of 32 (15.6%) and IgG in 20 out of 32 (75%). In pregnant women, specific IgM was detected in 4.8% (4/83) and IgG in 20.5% (17/83). The frequency of IgG detection was significantly higher in infertile than in pregnant women (p < 0.000). Thirteen out of 20 (65%) women who underwent laparoscopic examination had evidence of chronic inflammatory disease described as yellowish viscous cysts resembling "frog eggs" in Douglas, utero and/or perihepatitis. Twelve out of fourteen (86%) infertile women with positive serology for C. trachomatis presented one or more of these laparoscopic findings. C. trachomatis antigen was detected in 2 out of 10 tubal biopsies by direct immunofluorescence with monoclonal antibodies although isolation in McCoy cells was negative. Our results show the importance of C. trachomatis in infertility due to tubal occlusion and the need of C. trachomatis diagnosis in routine gynecologic analysis to prevent infertility and neonatal infection.

Forty-nine of 255 (19.2%) Argentinean children between the ages of 1 and 18 months without evidence of viral or bacterial infections, but with clinical and radiologic evidence of acute lower respiratory distress, had serologic evidence of recent Chlamydia trachomatis infection by the demonstration of specific IgM, seroconversion or 4-fold rise in titer or elevated titers by enzyme immunoassay and the microimmunofluorescence test. Recent C. trachomatis infection was detected in 28 of 166 (16.9%) of children with bronchiolitis and 18 of 89 (20.2%) with pneumonia. Three additional children with bronchiolitis had Chlamydia pneumoniae-specific antibody. There was a significantly higher prevalence of C. trachomatis infection in children living in La Plata city orphanage (26 of 74, 35.1%) than in those attending 2 pediatric hospitals in Buenos Aires (23 of 181, 12.7%) (P less than 0.001). C. trachomatis infection was detected in all age groups up to 18 months. Thirty of 49 infections were in children older than 3 months of age and 16 were in children older than 6 months. These results suggest that C. trachomatis infection may be associated with bronchiolitis and pneumonia in children between the ages of 1 and 18 months of age in Argentina and that a proportion may be horizontally transmitted.

Infection of newborn immunocompetent (nu/+) mice with the XJ prototype strain of Junin virus, etiological agent of Argentine Hemorrhagic Fever, produces a lethal meningo-encephalitis due to cellular immune response. The same strain inoculated into athymic (nu/nu) mice produces an asymptomatic persistent infection. The purpose of this work was to determine the nu/nu mice response when infected with XJCl3, an attenuated Junin virus strain, since this strain behaves differently to the pathogenic prototype in various experimental hosts and humans. Fifty five suckling nu/nu mice and 45 nu/+ were inoculated intracerebrally with 10(3) PFU of the XJCl3 strain. Twenty nu/nu and 20 nu/+ were kept as uninoculated controls. Similar percentages of mortality were recorded for nu/nu and nu/+ infected animals (86 and 87%). In contrast, no morbi-mortality was detected in control animals which were kept in the same animal room. High virus titers were detected in brains and lungs of infected nu/nu at 7, 14, 21 and 70 days post-infection(pi). Virus titers in blood were 1 log lower than those found in organs. Immunohistochemical studies of brains showed viral antigen in the cytoplasm of cortical neurons at 21 and 70 days pi. An interstitial pneumonitis was detected in lungs of infected nu/nu at 7 and 21 days pi, while no lesions were observed in brains and spleens. Results show that the XJl3 strain behaves in a very different way in newborn nu/nu mice as the XJ prototype strain. Further studies are necessary to determine the pathogenic mechanisms involved.

The present study investigated whether C. callidus, a species belonging to the Calomys genus, is capable of developing experimentally a persistent Junin virus (JV) infection. Newborn and adult cricetids were inoculated with the attenuated XJ-Clone 3 strain of JV by intracerebral or mucosal route. The present results indicate that the species is susceptible to JV infection, capable of shedding virus chronically through saliva and developing a persistent infection as shown by the detection of virus in brain tissue at 60 days post infection. These findings, and the fact that this cricetid shares its distribution areas with Calomys musculinus and Akodon azarae, support C. callidus as a potential JV reservoir.

The aim of this study was to determine if Junin virus inactivated with formalin (FA) was immunogenic and able to elicit a protective response in the guinea pig. The XJ-Clone 3 strain of Junin virus grown in Vero cells was exposed to FA at 0 degrees C. The following inactivated antigens were prepared: A1, 0.1% FA for 50 hr; A2, 0.1% FA for 50 hr followed by concentration with polyethylene glycol (PEG); B1, 0.05% FA for 70 hr; B2, 0.05% FA for 70 hr plus PEG concentration; C, 0.1% FA for 50 hr followed by ultracentrifugation and purification by sucrose gradient. No residual infectivity was detected in any inactivated antigen either after two passages in newborn mice or by coculture with Vero cells. After immunization, high-neutralizing and low-immunofluorescent antibody titers wer obtained in adult mice and guinea pigs, thus showing that antigenicity was preserved. However, in spite of the presence of neutralizing antibodies, guinea pigs gained no protection against challenge with the highly pathogenic XJ strain. These results suggest that antibody amount and/or quality may be inadequate; alternatively, mechanisms other than humoral immunity, such as cellular response, not elicited by inactivated antigens may be essential for protection against Junin virus.

The usefulness of a method for detection of antibodies against Junin virus in whole blood was tested. N: NIH adult mice were inoculated with 10(3) PFU of attenuated XJ-Clon 3 Junin virus strain by intraperitoneal route and blood was obtained by retro-orbital puncture at 21 days post-infection. One blood aliquot (50 microliters) was collected in tubes containing a stabilizer solution for whole blood and another was processed for serum obtention. Immunofluorescent antibodies were tested on spot slides of a BHK/21 cell line persistently infected with Junin virus. High antibody titers (1/64 to 1/256) were detected in both whole blood and serum, with 66% coincidence between both procedures. These results show that the method of detection of antibodies in whole blood would be useful to test quickly for anti-Junin virus antibodies in seroepidemiologic studies, in endemic areas.

To assess the usefulness of the South American primate Cebus apella as a model for neurovirulence of Junín virus, eight monkeys were inoculated with 10(5) LD50 of the attenuated XJ-Clone 3 Junín virus strain by the intrathalamic route. After the second week, weight loss and polyadenopathies were observed in most animals, one-half of which had a transient leukothrombocytopenia. Moderate clinical central nervous system (CNS) involvement was present in four of eight monkeys, while the rest had only mild neurologic signs. All recovered except one, which developed a deep coma and was killed in a pre-mortem stage at 18 days post-infection (pi). Junín virus was isolated from the throat from five, from the blood from three, and from the brain from two monkeys. In the most severely ill animal, virus titers higher than viremia were detected in both inoculated and contralateral brain hemispheres, as well as in lung, lymph node, and small intestine. Junín antigens and "in vivo" bound immunoglobulins were detected by immunofluorescence (IF) in the brain of four animals at 18, 21, 40, and 155 days pi. Moderate lymphocytic parenchymal and meningeal infiltration were observed in the brain of four animals, and gliosis was also present in the most affected monkey. Although the clinical response to infection was not uniform, all infected monkeys developed high IF antibodies. Cebus apella cannot be used as a highly sensitive model for Argentine hemorrhagic fever (AHF). However, the results obtained show that the XJ-Clone 3 strain can replicate in the primate CNS and to induce lesions and immunoglobulin deposition. In addition, viral persistence is suggested by the late detection of viral antigens in brain at 40 and 155 days pi.