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Biomedical subjects

G Carballal

Publications and source records attributed to G Carballal.

At least 55 records · Page 3Linked to original sources
PubMed1983

[Detection of laboratory infections caused by Junín virus using the neutralization and immunofluorescence technics comparatively].

To study Junin virus infection among laboratory workers and to compare immunofluorescence and neutralization tests, blood samples were taken from 48 individuals, of which 42 were considered high risk personnel. None of the 16 low risk workers exhibited antibodies. Neutralizing antibodies were detected in 15 high risk laboratory workers. Nine of the latter were already known to carry antibodies from a previous survey in 1978. Titers detected were either at previous levels or slightly higher. Of the remaining 6 out of the 15 positive cases, 3 showed mild clinical and subclinical infection, equivalent to a 12% incidence rate over the 1978-1980 period. An adequate correlation was observed between neutralization and immunofluorescence test: 66.6% for both positive tests and 97.1% for both negative tests. Although the immunofluorescence test ies easier to perform the neutralization test appears to be more reliable clinically. The overall prevalence rate of neutralizing antibodies among non-vaccinated personnel was almost 19%, which warns against the health hazard involved in Junin virus handling.

Antibodies, Viral↗
PubMed1981

Junin virus infection of guinea pigs: immunohistochemical and ultrastructural studies of hemopoietic tissue.

An association between viral antigens, cytopathic effect (CPE) and viral titers in blood and lymphoid tissues suggests a direct CPE of Junin virus on the lymphopoietic organs of guinea pigs infected with 10(3) 50% lethal doses of the XJ prototype strain. After seven days of infection, all lymphoreticular organs had infectivity titers higher than those for blood. Virus was recovered from bone marrow and lymph nodes at day 5 after infection; peak titers were obtained from bone marrow, spleen, and lymph nodes after day 10. Granular specific fluorescence was detected in the cytoplasm of reticular monocytes after day 7; megakaryocytes showed positive fluorescence, but specific staining of other lymphoid cells was not observed. Necrosis of bone marrow, lymph nodes, and spleen was observed after day 9. CPE consisted of overdevelopment of reticuloendoplasmic cisterne of reticulomonocytes and myeloblasts. Typical Junin virus particles were observed. Reticular cells were gradually destroyed, and simultaneous necrosis of surrounding lymphoid cells was observed.

Animals↗
PubMed1981

Cell-mediated immunity and lymphocyte populations in experimental Argentine hemorrhagic fever (Junín Virus).

Guinea pigs infected with the XJ prototype strain of Junín virus reproduce the main features of Argentine hemorrhagic fever, showing hemorrhages, leukothrombocytopenia, and focal lymphoid tissue necrosis. Viral lymphotropism is shown by the presence of viral antigens, severe cytopathic effect, and high virus titers in lymphoid organs. A pronounced depression of humoral immune response to sheep erythrocytes as well as to the virus is described. This study was carried out to determine whether cellular immune response was also modified and which cell populations were affected. Delayed hypersensitivity skin reaction to purified protein derivative was found to be markedly depressed after infection. A noticeable decrease in both percentages and absolute T lymphocyte numbers, detected by E rosettes, in spleen and lymph nodes, together with a low absolute T cell number in peripheral blood, were observed. Total cell counts in spleen, lymph nodes, and peripheral blood were also reduced. On the contrary, no modification in percentages of B lymphocytes, as measured by EAC rosettes, was found. These results indicate that cell-mediated immunity is markedly impaired in guinea pigs infected with the XJ strain of Junín virus. Its relationship with the pathogenesis of the disease is discussed.

Animals↗
PubMed1980

Description of a BHK/21 cell line persistently infected with Junin virus: its use in diagnostic procedures.

A BHK/21 cell line persistently infected by an arenavirus is described. During four consecutive passages, 30-45% of the cells showed granular cytoplasmic antigen by indirect immunofluorescence, employing both Argentine hemorrhagic fever convalescent sera and sera from animals immunized with Junin virus. Virus isolated from the cells killed suckling mice but not adult mice and protected guinea pigs against further challenge with the virulent prototype strain of Junin virus. Neutralization tests showed that the virus isolated from the cells was neutralized by anti-Junin virus antisera. The usefulness of this cell line in rapid immunofluorescent serological procedures is described.

Animals↗
PubMed1979

Immunofluorescent anti-Junin virus antibodies in Argentine hemorrhagic fever.

Immunofluorescent anti-Junin virus antibodies were detected in 15 nonfatal cases of Argentine hemorrhagic fever between the 2nd and 3rd week after onset of symptoms. In most cases, antibodies appeared by the day of clinical improvement, or between 2 and 4 days later. It was interesting to note that in 5 of 11 cases studied, the first positive serum sample presented anti-Junin virus immunofluorescent antibodies in IgA. In 2 of these 5 cases, IgA was the only immunoglobulin with antibody activity in the early positive serum sample.

Animals↗
PubMed1978

Argentine hemorrhagic fever. Alterations of the complement system and anti-Junin-virus humoral response.

We investigated immunologic mechanisms and the role of complement in the pathogenesis of Argentine hemorrhagic fever, a disease caused by the Junin virus, a member of the arenavirus group. Total serum complement activity was reduced to 68 per cent of control values in patients with severe or moderate disease (P less than 0.001). C2, C3 and C5 values were also low (12 to 60 per cent) during the early acute period of the disease. However, serum C4 content was increased to 160 per cent of the control values in the same patients. Total complement activity returned to normal with clinical and laboratory recovery, at the time of detection of antibodies against Junin virus. C1q reactive material was found in four of 19 cases and no relation to the evolution of the disease could be established. These results suggest that immune complexes are not important in the pathogenesis of Argentine hemorrhagic fever, but that activation of the complement system has a role.

Antibodies, Viral↗
PubMed1977

Junín virus infection of guinea pigs: electron microscopic studies of peripheral blood and bone marrow.

Thin sections of peripheral white blood cells and samples of bone marrow from guinea pigs infected with Junín virus were examined by electron microscopy. In peripheral blood cells, 40% of the granulocytes showed cytoplasmic lysis seven days after viral infection. After day 11 up to 80% of these cells showed morphological alterations. However, no intra- or extracellular viral particles were detected in these samples. Microscopy of bone marrow preparations revealed that 10% of the cells were altered five days after infection, and approximately 50% were affected after nine days. At this stage the megakaryocyte channels were seen to contain pleomorphic particles with a mean diameter of 80-100 nm. These particles had a unit membrane envelope and internal dense granules similar to those observed during other arenavirus infections. Therefore, it is suggested that the effect of Junín virus upon megakaryocytes may be a factor responsible for the acute thrombocytopenia observed in Argentine hemorrhagic fever.

Animals↗
PubMed1977

A rapid method for detecting Junin virus viremia in the guinea pig.

A method for detecting Junin virus viremia in guinea pigs is described. The method consists of infecting BHK-21 cells with blood samples from infected guinea pigs; 48 h later, Junin virus antigens are detected in the cells by indirect immunofluorescence. Application of this technique to patients with Argentine hemorrhagic fever may lead to the quickest method for the virologic diagnosis of this disease.

Animals↗
PubMedDate not supplied

Etiologic, clinical, and pathologic analysis of 31 fatal cases of acute respiratory tract infection in Argentinian children under 5 years of age.

During a 3-year survey of 805 children with acute lower respiratory tract infection (ALRI) who were admitted to three hospitals in Buenos Aires, 31 fatal cases were recorded--a fatality rate of 3.8%. Of the 31 children who died, 77% were less than 1 year of age, 48% were boys, 58% were malnourished, 29% had previous respiratory disease, and 22% had previous congenital disease. All children who died had clinical diagnoses of pneumonia (71%) or bronchiolitis (29%). Autopsies were performed in 14 of the cases. Viral etiology was determined by both cell culture and indirect immunofluorescence (IIF) assay of either nasopharyngeal aspirates (NPA) or lung tissue and bacterial etiology was determined by isolation of organisms from blood, lung tissue, and/or pleural fluid. NPA was examined for Bordetella pertussis by IIF. Pathogens were identified in 65% of fatal cases. Seven cases were bacterial; seven cases were viral; and six cases resulted from mixed infections. Lung tissue yielded positive etiologic results in 10 of 13 cases. Histopathologic examination performed on specimens from the 14 autopsied children revealed necrotizing bronchiolitis with intranuclear inclusions (n = 5) and multifocal pneumonia (n = 9).

Acute Disease↗
PubMedDate not supplied

Etiologic and clinical evaluation of acute lower respiratory tract infections in young Argentinian children: an overview.

This paper summarizes the first study on clinical, etiologic, and epidemiologic features of acute lower respiratory tract infection (ALRI) in children in Argentina. A total of 1,003 children less than 5 years of age (805 inpatients and 198 outpatients) presenting with ALRI were studied during a 40-month period. Nasopharyngeal aspirate (NPA), blood, urine, and throat-swab samples were collected when each child was first seen for care. Virologic studies were performed on the NPA by means of indirect immunofluorescence and isolation of virus in cell culture. Bacteriologic studies primarily were done by means of culture of blood or pleural fluid (when available); Bordetella pertussis and Mycoplasma pneumoniae, however, were searched for by the use of immunofluorescence and complement-fixation testing, respectively, in paired sera. Respiratory syncytial virus was the most commonly isolated virus, followed by adenovirus, parainfluenza virus, and influenza virus. Streptococcus pneumoniae was the most frequently isolated bacterium, followed by B. pertussis and Haemophilus influenzae type b. Overall, the patient fatality rate was 3.8% among inpatients with pneumonia or bronchiolitis.

Acute Disease↗
PubMedDate not supplied

Isolation and identification of viral agents in Argentinian children with acute lower respiratory tract infection.

From a total population of 1,002 children with acute lower respiratory infection (ALRI), identification of virus was achieved in 304 cases. In this survey, 1,000 nasopharyngeal aspirate and 13 lung tissue samples were tested in four cell lines (HEp-2, MRC-5, MDCK, and LLC-MK2) and by indirect immunofluorescence (IIF), while 242 paired sera were studied by complement fixation. Respiratory syncytial virus (RSV) was the most frequently detected agent (n = 183), followed by adenovirus (n = 28), parainfluenza (n = 5) and 3 (n = 16) viruses, and influenza A (n = 10) and B (n = 4) viruses. The sensitivity and specificity of IIF identification vs. isolation in cell culture were high for RSV (91.5% and 94.9%, respectively). However, IIF proved poorly sensitive for detection of adenovirus (sensitivity, 23.8%; specificity, 100%). The complement-fixation test proved the least effective, with a sensitivity of only 41.5%. Therefore, on the basis of our experience, it appears that the yield for positive diagnosis of virus is increased if both isolation in multiple cell lines and identification by means of IIF are used. Our survey provides for the first time reliable data on the viral etiology of ALRI in Argentina, as determined by three different methods.

Adenoviruses, Human↗
PubMedDate not supplied

[Intracerebral infection of athymic mice with an attenuated strain of Junín virus].

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.

Animals↗
PubMedDate not supplied

[Serologic response measured by complement fixation in children with acute respiratory infection].

The aim of this work was to evaluate the sensitivity of complement fixation for serological diagnosis of lower acute respiratory infections (ARI) in small children in comparison with direct methods such as indirect immunofluorescence (IIF) on nasopharyngeal aspirate and tissue culture isolation. Sera from children under 5 year of age with ARI were studied by complement fixation for 6 respiratory viruses (respiratory syncytial virus (RSV), adenovirus, influenza A and B and parainfluenza 1 and 3). In all, 264 pairs of serum samples from children with viral ARI diagnosis (n:135) or from doubtful cases (n:90) were studied. Thirty nine sera were anticomplementary. In samples from confirmed viral ARI patients, seroconversion was detected in 38%, whereas from those with a doubtful diagnosis it was only 14%. Seroconversion for RSV and adenovirus was 39% and 50%, respectively. On correlating seroconversion for the 6 viruses according to age group, 20% positivity was found in the 0-5 month-old group, 35% in the 6-10 month-old and 30% in those over 11 months of age. For RSV alone, 0-5 month-old patients presented 25% seroconversion, and in those over 6 months of age the percentage exceeded 60% (p less than 0.001). Complement fixation test sensitivity vs direct methods (IIF and/or culture) was 38.5%). Our findings confirm the low sensitivity of complement fixation to detect antibodies in ARI, particularly in children under 6 months of age and support the higher efficacy of direct diagnostic methods. However, complement fixation serology is useful for epidemiological studies in children over 6 months of age, since over 60% of RSV were readily detected.

Child, Preschool↗