Prevalence of serum antibodies to hantavirus in a rural population from the southern state of Santa Catarina, Brazil

Introduction: Rodent-borne hantaviruses cause severe human diseases. We completed a serological survey of hantavirus infection in rural inhabitants of Turvo County, in the southern state of Santa Catarina, Brazil, in which seropositivity for hantavirus was correlated to previous disease in the participants. Methods: The levels of IgG antibodies to hantavirus Araraquara in the sera of 257 individuals were determined using an immunoenzymatic assay. Results: IgG antibodies to hantavirus were found in 2.3% of the participants. All seropositive participants reported previous disease with symptoms suggestive of hantavirus cardiopulmonary syndrome. Conclusions: Human infections causing unreported cardiopulmonary syndrome probably occur in the southern state of Santa Catarina.

Detection of IgG antibodies to Neospora caninum and Toxoplasma gondii in dogs examined in a veterinary hospital from Brazil

A total of 163 dogs with neuromuscular, respiratory and/or gastrointestinal disorders, was admitted at the Veterinary Hospital, Federal University of Uberlandia, Brazil, and submitted to serology for Toxoplasma gondii and Neospora caninum. Assays for T gondii included indirect haemagglutination (IHA), indirect fluorescent antibody (IFAT-Tg), immunoenzymatic (ELISA), and immunoblotting (IB-Tg). Assays for N, caninum included IFAT-Nc and immunoprecipitation (IP-Nc). Based on concordant results by three serological tests (IHA, IFAT-Tg and ELISA) for T gondii, and divergent results further confirmed by IB-Tg for reactivity to TgSAG1, the 163 sera were divided into two groups: 59 (36%) Tg-seropositive samples and 104 (64%) Tg-seronegative samples. Antibodies to Neospora were detected in 11 (6.7%) out of 163 analyzed dog sera, with 5 (3.1 %) samples reactive to both parasites (Tg+/Nc+), and 6 (3.7%) reactive only to Neospora (Tg-/Nc+). Antibodies only to T: gondii were found in 54 (33%) samples. Among the 11 Neospora-positive sera analyzed by IB-Tg, the five sera Tg+/Nc+ showed strong reactivity to Toxoplasma antigens, especially to TgSAG1 (p30). No reactivity was observed to TgSAG1 in the six samples Tg-/Nc+. By TP-Nc, two highly immunodominant antigens (29 and 35 kDa proteins) were recognized by all 11 IFAT-Nc positive sera. Our results suggest that the infection by N, caninum can be concomitantly present in dogs from this area, although less common, and therefore should be considered in the differential clinical diagnosis with T. gondii in dogs presenting neuromuscular, respiratory and/or gastrointestinal disorders. (C) 2001 Elsevier B.V. B.V. All rights reserved.

Antibody levels to hantavirus in inhabitants of western Santa Catarina State, Brazil

Hantavirus cardiopulmonary syndrome (HCPS) is an infectious disease caused by hantaviruses of the family Bunyaviridae, and is transmitted by aerosols of excreta of infected rodents. The aim of the present study was to determine antibody levels to hantavirus in the population that lives at frontier of Brazil and Argentina. Participated of the study 405 individuals living in the municipalities of Bandeirante, Santa Helena, Princesa and Tunapolis, state of Santa Catarina, Brazil. IgG antibodies to hantavirus were analyzed in sera by an ELISA that uses a recombinant N protein of Araraquara hantavirus as antigen. The results were also confirmed by immunofluorescent test. Eight individuals showed antibodies to hantavirus (1.97% positivity), with serum titers ranging from 100 to 800. Six seropositives were males, older than 30 years and farmers. Our results reinforce previous data on hantavirus circulation and human infections in the southern border of Brazil with Argentina.

A novel antigen capture ELISA for the specific detection of IgG antibodies to elephant endotheliotropic herpes virus

BACKGROUND Elephants are classified as critically endangered animals by the International Union for Conservation of Species (IUCN). Elephant endotheliotropic herpesvirus (EEHV) poses a large threat to breeding programs of captive Asian elephants by causing fatal haemorrhagic disease. EEHV infection is detected by PCR in samples from both clinically ill and asymptomatic elephants with an active infection, whereas latent carriers can be distinguished exclusively via serological assays. To date, identification of latent carriers has been challenging, since there are no serological assays capable of detecting seropositive elephants. RESULTS Here we describe a novel ELISA that specifically detects EEHV antibodies circulating in Asian elephant plasma/serum. Approximately 80 % of PCR positive elephants display EEHV-specific antibodies. Monitoring three Asian elephant herds from European zoos revealed that the serostatus of elephants within a herd varied from non-detectable to high titers. The antibody titers showed typical herpes-like rise-and-fall patterns in time which occur in all seropositive animals in the herd more or less simultaneously. CONCLUSIONS This study shows that the developed ELISA is suitable to detect antibodies specific to EEHV. It allows study of EEHV seroprevalence in Asian elephants. Results confirm that EEHV prevalence among Asian elephants (whether captive-born or wild-caught) is high.

Comparative recognition by human IgG antibodies of recombinant proteins representing three asexual erythrocytic stage vaccine candidates of Plasmodium vivax

In previous immuno-epidemiological studies of the naturally acquired antibody responses to merozoite surface protein-1 (MSP-1) of Plasmodium vivax, we had evidence that the responses to distinct erythrocytic stage antigens could be differentially regulated. The present study was designed to compare the antibody response to three asexual erythrocytic stage antigens vaccine candidates of P. vivax. Recombinant proteins representing the 19 kDa C-terminal region of MSP-1(PvMSP19), apical membrane antigen n-1 ectodomain (PvAMA-1), and the region II of duffy binding protein (PvDBP-RII) were compared in their ability to bind to IgG antibodies of serum samples collected from 220 individuals from the state of Pará, in the North of Brazil. During patent infection with P. vivax, the frequency of individuals with IgG antibodies to PvMSP119, PvAMA-1, and PvDBP-RII were 95, 72.7, and 44.5% respectively. Although the frequency of responders to PvDBP-RII was lower, this frequency increased in individuals following multiple malarial infections. Individually, the specific antibody levels did not decline significantly nine months after treatment, except to PvMSP119. Our results further confirm a complex regulation of the immune response to distinct blood stage antigens. The reason for that is presently unknown but it may contribute to the high risk of re-infection in individuals living in the endemic areas.

Serological evidence of hantavirus infection in rural and urban regions in the state of Amazonas, Brazil

Hantavirus disease is caused by the hantavirus, which is an RNA virus belonging to the family Bunyaviridae. Hantavirus disease is an anthropozoonotic infection transmitted through the inhalation of aerosols from the excreta of hantavirus-infected rodents. In the county of Itacoatiara in the state of Amazonas (AM), Brazil, the first human cases of hantavirus pulmonary and cardiovascular syndrome were described in July 2004. These first cases were followed by two fatal cases, one in the municipality of Maues in 2005 and another in Itacoatiara in 2007. In this study, we investigated the antibody levels to hantavirus in a population of 1,731 individuals from four different counties of AM. Sera were tested by IgG/IgM-enzyme-linked immune-sorbent assay using a recombinant nucleocapsid protein of the Araraquara hantavirus as an antigen. Ten sera were IgG positive to hantavirus (0.6%). Among the positive sera, 0.8% (1/122), 0.4% (1/256), 0.2% (1/556) and 0.9% (7/797) were from Atalaia do Norte, Careiro Castanho, Itacoatiara and Labrea, respectively. None of the sera in this survey were IgM-positive. Because these counties are distributed in different areas of AM, we can assume that infected individuals are found throughout the entire state, which suggests that hantavirus disease could be a local emerging health problem.

IgG subclass profile of serum antibodies to Leishmania chagasi in naturally infected and vaccinated dogs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

High seroprevalence of antibodies to varicella zoster virus in adult women in a tropical climate

OBJECTIVES To determine whether the seroprevalence of antibodies to varicella zoster virus (VZV) in adults is similar to that reported in tropical populations elsewhere. METHODS We measured the seroprevalence of VZV IgG antibodies, using an enzyme immunoassay (EIA) in women attending an antenatal clinic in an urban centre in tropical Australia. RESULTS The overall seroprevalence of VZV antibodies in 298 women was 92% (95% CI 88-95), with no difference between women who spent their childhoods in the tropics and colleagues. None of the overseas-born women was seronegative. CONCLUSION The seroprevalence of VZV antibodies in this tropical population in Australia is as high as that reported from temperate regions, suggesting that social and cultural factors and population mobility are more important determinants of age distribution of VZV immunity than tropical climate.

Demonstration of IgE Antibodies to Nucleic Acid Antigens in Patients with Sle

Using a combination of avidin-biotin microELISA and solid phase radioimmunoassay, we examined sera from 23 patients with systemic lupus erythematosus (SLE), two patients with established sensitivity to ingested shrimp, and 15 healthy normal subjects. In addition to IgG antibodies, varying amounts of IgE antibodies specific for native DNA (nDNA), denatured or single-stranded DNA (dnDNA), RNA, and tRNA were demonstrable in the sera of SLE patients, but not in the sera of normal subjects. A comparison of the specificity of nucleic acid-specific IgE antibodies present in the sera of shrimp-sensitive patients with those present in the sera of seven SLE patients revealed that the IgE antibodies in the sera of shrimp-sensitive patients specifically recognized shrimp tRNA but not yeast tRNA, calf thymus RNA, or calf thymus DNA, while those present in the sera of patients with SLE recognized all these nucleic acid antigens. The IgE antibodies directed against nDNA, dnDNA, RNA, and tRNA may mediate mast cell and basophil degranulation and thus contribute both to immediate-type hypersensitivity phenomena including hives seen in patients with SLE and to the localization of IgE-nucleic acid complexes in target

Gene enrichment using antibodies to DNA/RNA hybrids : mapping the ribosomal DNA of slime mold and rat

A novel method for gene enrichment has been developed and applied to mapping the rRNA genes of two eucaryotic organisms. The method makes use of antibodies to DNA/RNA hybrids prepared by injecting rabbits with the synthetic hybrid poly(rA)•poly(dT). Antibodies which cross-react with non-hybrid nucleic acids were removed from the purified IgG fraction by adsorption on columns of DNA-Sepharose, oligo(dT)-cellulose, and poly(rA)-Sepharose. Subsequent purification of the specific DNA/RNA hybrid antibody was carried out on a column of oligo(dT)-cellulose to which poly(rA) was hybridized. Attachment of these antibodies to CNBr-activated Sepharose produced an affinity resin which specifically binds DNA/RNA hybrids.

In order to map the rDNA of the slime mold Dictyostelium discoideum, R-loops were formed using unsheared nuclear DNA and the 178 and 268 rRNAs of this organism. This mixture was passed through a column containing the affinity resin, and bound molecules containing R- loops were eluted by high salt. This purified rDN A was observed directly in the electron microscope. Evidence was obtained that there is a physical end to Dictyostelium rDN A molecules approximately 10 kilobase pairs (kbp) from the region which codes for the 268 rRNA. This finding is consistent with reports of other investigators that the rRNA genes exist as inverse repeats on extra-chromosomal molecules of DNA unattached to the remainder of the nuclear DNA in this organism.

The same general procedure was used to map the rRNA genes of the rat. Molecules of DNA which contained R-loops formed with the 188 and 288 rRNAs were enriched approximately 150- fold from total genomal rat DNA by two cycles of purification on the affinity column. Electron microscopic measurements of these molecules enabled the construction of an R-loop map of rat rDNA. Eleven of the observed molecules contained three or four R-loops or else two R-loops separated by a long spacer. These observations indicated that the rat rRNA genes are arranged as tandem repeats. The mean length of the repeating units was 37.2 kbp with a standard deviation of 1.3 kbp. These eleven molecules may represent repeating units of exactly the same length within the errors of the measurements, although a certain degree of length heterogeneity cannot be ruled out. If significantly shorter or longer repeating units exist, they are probably much less common than the 37.2 kbp unit.

The last section of the thesis describes the production of antibodies to non-histone chromosomal proteins which have been exposed to the ionic detergent sodium dodecyl sulfate (SDS). The presence of low concentrations of SDS did not seem to affect either production of antibodies or their general specificity. Also, a technique is described for the in situ immunofluorescent detection of protein antigens in polyacrylamide gels.

A time-resolved immunoassay to measure serum antibodies to the rotavirus VP6 capsid protein

The rotavirus (RV) inner capsid protein VP6 is widely used to evaluate immune response during natural infection and in vaccine studies. Recombinant VP6 from the most prevalent circulating rotavirus strains in each subgroup (SG) identified in a birth cohort of children in southern India [SGII (G1P[8]) and SGI (G10P[11])] were produced. The purified proteins were used to measure VP6-specific antibodies in a Dissociation-Enhanced Lanthanide Fluorometric Immunoassay (DELFIA). The ability of the assay to detect a =2 fold rise in IgG level in a panel of serum samples from a longitudinal study was compared to a gold standard virus-capture ELISA. A strong association was observed between the assays (p

Antibodies to the structural polypeptides of measles virus following acute infection and in SSPE

A solid-phase radioimmunoassay was used to determine the specificity of IgG antibodies from normal sera, sera and CSF from patients with SSPE for the structural polypeptides of measles virus. The polypeptide specificity of antibodies from these sources were qualitatively similar; these results indicate antigenic cross-reactivity between SSPE-derived (Mantooth) and non-SSPE-derived strains of measles virus and stimulation of antibody formation by comparable antigens.

Naturally Acquired Antibodies to Plasmodium vivax Duffy Binding Protein (DBP) in Rural Brazilian Amazon

Duffy binding protein (DBP), a leading malaria vaccine candidate, plays a critical role ill Plasmodium vivax erythrocyte invasion. Sixty-eight of 366 (18.6%) subjects had IgG anti-DBP antibodies by enzyme-linked immunosorbent assay (ELISA) in a community-based cross-sectional survey ill the Brazilian Amazon Basin. Despite Continuous exposure to low-level malaria transmission, the overall seroprevalence decreased to 9.0% when the Population was reexamined 12 months later. Antibodies from 16 of 50 (360%) Subjects who were ELISA-positive at the baseline were able to inhibit erythrocyte binding to at least one of two DBP variants tested. Most (13 of 16) of these subjects still had inhibitory antibodies when reevaluated 12 months later. Cumulative exposure to malaria was the strongest predictor of DBP seropositivity identified by Multiple logistic regression models in this population. The poor antibody recognition of DBP elicited by natural exposure to P. vivax in Amazonian populations represents a challenge to be addressed by vaccine development strategies.