Specific circulating immune complexes in acute chagas' disease

The presence of circulating immune complexes formed by IgM and IgG (CIC-IgM and CIC-IgG) was investigated, using antigen-specific enzyme-immunoassays (ELISA), in 30 patients with acute Chagas' disease who showed parasitemia and inoculation chagoma. Control population consisted of patients with chronic T. cruzi infection (30), acute toxoplasmosis 10), leishmaniasis (8), rheumatoid arthritis (3) and healthy individuals with negative serology for Chagas* disease (30). Acute chagasic patients were 100% CIC-IgG and 96.66% CIC-IgM positive whereas immunofluorescence tests yielded 90% and 86.66% of positivity for specific IgG and IgM antibodies, respectively. Chronic patients were 68% CIC-IgG and 0% CIC-IgM positive. The 30 negative and the 21 cross-reaction controls proved negative for ELISA (CIC-IgM and CIC-IgG). The high sensitivity of ELISA assays would allow early immunologic diagnosis, as well as prompt treatment, of acute T. cruzi infection, thus eliminating the problem of the false-positive and false-negative results which affects traditional methods for detection of circulating antibodies.Se investigo la presencia de complejos inmunes circulantes formados por IgM e IgG (CIC-IgM y CIC-IgG), utilizando enzimoinmu-noensayos ELISA) antígeno-específicos, en 30 pacientes con enfermedad de Chagas aguda que presentaban parasitemia y chagoma de inocu-lación. La población control estaba formada por pacientes con infección crônica por T. cruzi (30), toxoplasmosis aguda (10), leishmaniasis (8), artritis reumatoidea (3) e individuos sanos con serología negativa para Chagas (30). Los pacientes chagásicos agudos fueron 100% CIC-IgG y 96,66% CIC-IgM positivos, mientras que Ias pruebas de inmunofluorescencia para anti-cuerpos específicos de tipo IgG e IgM mostra-ron 90% y 86,66% de positividad, respectivamente. Los pacientes crônicos fueron 68% CIC-IgG y 0% CIC-IgM positivos. El resto de los controles arrojaron resultados negativos por ELISA CIC-IgM y CIC-IgG). La alta sensibilidad dei ELISA permitiria un diagnóstico inmunológico temprano, como así también un tra-tamiento inmediato, de la infeccin aguda por T. cruzi, eliminando así el problema de resultados falsos-positivos y falsos-negativos que afecta a los métodos tradicionales para detección de anticuerpos circulantes

ELISA technique for detection of Trypanosoma cruzi circulating antigens and immune complexes in San Luis, Argentina

The ELISA technique for detection of T. cruzi circulating antigens (cAg) and immune complexes (CIC) in the sera of chronic chagasic patients was field-tested in a well-known endemic area of Argentina (San Luis province). Of 215 individuals screened, 51 were positive for ELISA-CIC and 45 for ELISA-cAg. Seventy four subjects were considered por T. cruzi-infected, as they showed Serologic reactivity at least by two different techniques. In this group, 49 (66.21%) were ELISA-CIC positive, whereas in 43 (58.11%) of them cAg was found by ELISA. Unspecific reactions were observed in only 2 cases with reactive serology for Chagas disease. Within the group considered as noninfected, a false-positive outcome was obtained at low dilution by one of the Serologic tests in 16 (11.35%) of 141 individuals. These sera yielded consistently negative results by ELISA-CIC and cAg, showing the utility of antigen detection in situations of conflictive serology. While antibody determination merely provides an indirect proof of infection, our ELISA tests for demonstration of T. cruzi-specific antigenic fractions in the host's circulation allow a parasitologic diagnosis in chronic patients, with higher sensitivity than that exhibited by traditional methods for detection of the whole parasiteEn una zona endémica de la República Argentina se llevó a cabo un ensayo de campo de la prueba inmunoenzimática ELISA para la detección de antígenos (cAg) y complejos inmunes circulantes (CIC) en sueros de pacientes chagásicos crónicos. Del total de 215 muestras de sangre analizadas, 51 fueron positivas para ELISA-CIC y 45 lo fueron para ELISA-cAg. De los 74 (34,32% de la población) sujetos considerados infectados con dos reacciones serológicas positivas, 49 (66,21%) presentaron CIC en suero, en tanto que en 43 (58,11%) de ellos se encontró cAg por ELISA. Solo en 2 casos serológicamente no reactivos, se detectaron inespecíficamente CIC y cAg. Dentro del grupo considerado no infectado, se observó reactividad inespecífica de bajo título por una de las pruebas serológicas en 16 (11,35%) de 141 individuos. Estos sueros arrojaron resultados consistentemente negativos por ELISA-CIC y cAg demostrando la utilidad de estos métodos de diagnóstico antigénico en casos de serología conflictiva. La determinación de fracciones antigénicas circulantes por ELISA en individuos chagásicos crónicos permite evidenciar la infección por T. cruzi de manera más directa que midiendo la respuesta inmune humoral en el huésped, presentando además mayor sensibilidad que el diagnóstico parasitológico clásic

Hepatitis C Virus Infection in Infants and Children from Argentina

Hepatitis C virus (HCV) infection is uncommon in children, and its natural history is still unknown. Our aim was to analyze exposure to HCV in 48 infants and children in Argentina and to evaluate consecutive samples in 26 of them to study the outcome of HCV infection in early stages. HCV viremia, as determined by reverse transcription-PCR (RT-PCR) from the 5′ untranslated region, showed continuously positive, occasionally positive, and negative patterns during follow-up. Restriction fragment length polymorphism was performed on RT-PCR-positive samples to evaluate HCV genotype. Genotype 1 turned out to be predominant, and no patient displayed a genotype shift during the observation period. Perinatal HCV infection was predominantly observed in patients born to mothers coinfected with HCV and human immunodeficiency virus. HCV viral load was detected by means of the AMPLICOR MONITOR, version 2.0, kit. No correlation was observed between HCV viral load and alanine aminotransferase and aspartate aminotransferase levels, although we detected a trend towards higher levels among patients displaying consecutive positive HCV RT-PCR results. Our results demonstrate that pediatric HCV infection is characterized by high viral loads and diverse HCV viremia patterns, independent of both age and route of transmission in the population under study. Further research is necessary to determine whether the high rate of HCV replication is related to virus variability or to host immune response

Hepatitis C Virus Isolates from Argentina Disclose a Novel Genotype 1-Associated Restriction Pattern

Hepatitis C virus isolates which disclosed a novel genotype 1-associated restriction pattern by restriction fragment length polymorphism analysis were characterized. Except for a mother and child pair, the patients were unrelated. Sequence analysis showed a G→A substitution leading to a new RsaI recognition site. Phylogenetic analysis revealed that these isolates constitute a novel genetic lineage within the main cluster of genotype 1 strains

Intranasal vaccination with recombinant outer membrane protein CD and adamantylamide dipeptide as the mucosal adjuvant enhances pulmonary clearance of Moraxella catarrhalis in an experimental murine model.

Moraxella catarrhalis causes acute otitis media in children and lower respiratory tract infections in adults and elderly. In children the presence of antibodies against the highly conserved outer membrane protein CD correlates with protection against infection, suggesting that this protein may be useful as a vaccine antigen. However, native CD is difficult to purify, and it is still unclear if recombinant CD (rCD) is a valid alternative. We performed a side-by-side comparison of the immunogenicities and efficacies of vaccine formulations containing native CD and rCD with adamantylamide dipeptide as the mucosal adjuvant. Intranasal vaccination of mice stimulated the production of high CD-specific antibody titers in sera and of secretory immunoglobulin A in mucosal lavages, which cross-recognized both antigens. While vaccination with native CD increased the number of interleukin-2 (IL-2)- and gamma interferon-producing cells, rCD mainly stimulated IL-4-secreting cells. Nevertheless, efficient bacterial clearance was observed in the lungs of challenged mice receiving native CD and in the lungs of challenged mice receiving rCD (96% and 99%, respectively). Thus, rCD is a promising candidate for incorporation in vaccine formulations for use against M. catarrhalis

Nasal immunization with Burkholderia multivorans outer membrane proteins and the mucosal adjuvant adamantylamide dipeptide confers efficient protection against experimental lung infections with B. multivorans and B. cenocepacia

Chronic lung infection by opportunistic pathogens, such as Pseudomonas aeruginosa and members of the Burkholderia cepacia complex, is a major cause of morbidity and mortality in patients with cystic fibrosis. Outer membrane proteins (OMPs) of gram-negative bacteria are promising vaccine antigen candidates. In this study, we evaluated the immunogenicity, protection, and cross-protection conferred by intranasal vaccination of mice with OMPs from B. multivorans plus the mucosal adjuvant adamantylamide dipeptide (AdDP). Robust mucosal and systemic immune responses were stimulated by vaccination of naive animals with OMPs from B. multivorans and B. cenocepacia plus AdDP. Using a mouse model of chronic pulmonary infection, we observed enhanced clearance of B. multivorans from the lungs of vaccinated animals, which correlated with OMP-specific secretory immunoglobulin A responses. Furthermore, OMP-immunized mice showed rapid resolution of the pulmonary infection with virtually no lung pathology after bacterial challenge with B. multivorans. In addition, we demonstrated that administration of B. multivorans OMP vaccine conferred protection against B. cenocepacia challenge in this mouse infection model, suggesting that OMPs provide cross-protection against the B. cepacia complex. Therefore, we concluded that mucosal immunity to B. multivorans elicited by intranasal vaccination with OMPs plus AdDP could prevent early steps of colonization and infection with B. multivorans and also ameliorate lung tissue damage, while eliciting cross-protection against B. cenocepacia. These results support the notion that therapies leading to increased mucosal immunity in the airways may help patients with cystic fibrosis