Dengue-1 Virus Isolation during First Dengue Fever Outbreak on Easter Island, Chile

Dengue virus was detected for the first time in Chile, in an outbreak of dengue fever on Easter Island. The virus was isolated in tissue culture and characterized by reverse transcription–polymerase chain reaction as being dengue type 1

Incubation Period of Hantavirus Cardiopulmonary Syndrome

The potential incubation period from exposure to onset of symptoms was 7–39 days (median 18 days) in 20 patients with a defined period of exposure to Andes virus in a high-risk area. This period was 14–32 days (median 18 days) in 11 patients with exposure for <48 hours

Correlation between female sex, IL28B genotype, and the clinical severity of bronchiolitis in pediatric patients

Background: Single-nucleotide polymorphisms (SNPs) that impact on the differential expression of interleukin 28B (IL28B) are implicated in the progression of viral-induced diseases. In this prospective longitudinal cohort study, we evaluated the association between IL28B SNPs rs12979860 and rs8099917 and the clinical outcome of bronchiolitis in pediatric patients. Methods: A total of 682 infants suffering from bronchiolitis, categorized based on the final clinical outcome as mild or severe, were genotyped for IL28B SNPs rs12979860 and rs8099917. Results: When infants were categorized exclusively based on the final clinical outcome, no association was established between IL28B SNPs and the severity of bronchiolitis. However, when stratified by sex, the homozygotes for the minor alleles of rs12979860 (T) and rs8099917 (G) were associated with a mild disease in girls but not in boys. Conclusion: SNPs rs12979860 and rs8099917 correlate with the severity of bronchiolitis and display a sex bias, where GG rs8099917 and TT rs12979860 genotypes are associated with a mild disease in girls but not in boys. These findings suggest that innate immunity and female sex links with the outcome of the diseases induced by respiratory viruses, such as RSV. © 2019, International Pediatric Research Foundation, Inc.Indexación: Scopu

Hantavirus Prevalence in the IX Region of Chile

An epidemiologic and seroprevalence survey was conducted (n=830) to assess proportion of persons exposed to hantavirus in IX Region Chile, which accounts for 25% of reported cases of hantavirus cardiopulmonary syndrome. This region has three geographic areas with different disease incidences and a high proportion of aboriginals. Serum samples were tested for immunoglobulin (Ig) G antibodies by enzyme-linked immunosorbent assay against Sin Nombre virus N antigen by strip immunoblot assay against Sin Nombre, Puumala, Río Mamoré, and Seoul N antigens. Samples from six patients were positive for IgG antibodies reactive with Andes virus; all patients lived in the Andes Mountains. Foresting was also associated with seropositivity; but not sex, age, race, rodent exposure, or farming activities. Exposure to hantavirus varies in different communities of IX Region. Absence of history of pneumonia or hospital admission in persons with specific IgG antibodies suggests that infection is clinically inapparent

Highly Differentiated, Resting Gn-Specific Memory CD8+ T Cells Persist Years after Infection by Andes Hantavirus

In man, infection with South American Andes virus (ANDV) causes hantavirus cardiopulmonary syndrome (HCPS). HCPS due to ANDV is endemic in Southern Chile and much of Argentina and increasing numbers of cases are reported all over South America. A case-fatality rate of about 36% together with the absence of successful antiviral therapies urge the development of a vaccine. Although T-cell responses were shown to be critically involved in immunity to hantaviruses in mouse models, no data are available on the magnitude, specificity and longevity of ANDV-specific memory T-cell responses in patients. Using sets of overlapping peptides in IFN-γ ELISPOT assays, we herein show in 78 Chilean convalescent patients that Gn-derived epitopes were immunodominant as compared to those from the N- and Gc-proteins. Furthermore, while the relative contribution of the N-specific response significantly declined over time, Gn-specific responses remained readily detectable ex vivo up to 13 years after the acute infection. Tetramer analysis further showed that up to 16.8% of all circulating CD3+CD8+ T cells were specific for the single HLA-B*3501-restricted epitope Gn465–473 years after the acute infection. Remarkably, Gn465–473–specific cells readily secreted IFN-γ, granzyme B and TNF-α but not IL-2 upon stimulation and showed a ‘revertant’ CD45RA+CD27−CD28−CCR7−CD127− effector memory phenotype, thereby resembling a phenotype seen in other latent virus infections. Most intriguingly, titers of neutralizing antibodies increased over time in 10/17 individuals months to years after the acute infection and independently of whether they were residents of endemic areas or not. Thus, our data suggest intrinsic, latent antigenic stimulation of Gn-specific T-cells. However, it remains a major task for future studies to proof this hypothesis by determination of viral antigen in convalescent patients. Furthermore, it remains to be seen whether Gn-specific T cells are critical for viral control and protective immunity. If so, Gn-derived immunodominant epitopes could be of high value for future ANDV vaccines

Fuente de infección de Bordetella pertussis en lactantes hospitalizados por coqueluche

Background: Despite pertussis vaccination, very young infants have the highest rates of morbidity and mortality caused by the microorganism. Aim: To determine the source of Pertussis infection in infants aged six months or less in Chile. Material and Methods: Twenty six household contacts of 10 young infants hospitalized with confirmed Pertussis were studied for the presence of Bordetella Pertussis by polyme-rase chain reaction (PCR). Clinical and demographic data were analyzed. Results: Respiratory symptoms were present in 20 (77%) contacts, being cough the most common. Pertussis cases were identifed in every household and in 18 (72%) of the household members. four members with B.pertussis were asymptomatic. Source of infection was identifed in 80% (8/10) of the infant cases with ages ranging from 6 to 62 years. Half of primary cases had positive PCR and their cough duration was significantly shorter compared to primary cases with negative PCR. Conclusions: B. pertussis transmission to young infants occurred mainly within the household where adults are generally the source of the infection. Risk factors for infant infection are the same as in developed countries. Therefore, the same strategies, such as routine vaccination in adolescents and adults or cocoon strategy, will help to prevent this disease in infants

Range expansion of Oligoryzomys longicaudatus (Rodentia, Sigmodontinae) in Patagonian Chile, and first record of Hantavirus in the region Ampliación del rango de distribución de Oligoryzomys longicaudatus (Rodentia, Sigmodontinae) en la Patagonia de Chile y primer registro de Hantavirus en la región

At present, 20 species of Oligoryzomys (Rodentia, Sigmodontinae) are recognized in the Neotropical region, most of them distinguished by their karyotypes, which fluctuates between 46-70 chromosomes. Two species are currently recognized in Chile, Oligoryzomys longicaudatus (Bennet, 1832; "colilargo" or the long-tailed pygmy rice rat; 2n = 56), which ranges from 27° to approximately 51° S, and O. magellanicus (Bennet, 1836; Magellanic pygmy rice rat; 2n = 54), south of 51° S in the Patagonian region of Chile and Argentina. As part of an ongoing research on the southern Patagonia of Chile, we report the results of small mammal samplings in six localities. We karyotyped 28 specimens and we also sequenced the hypervariable mtDNA region I in 22 individuals, aligning these sequences with an under development phylogeny of O. longicaudatus. We also evaluated the serology and viral charge in all captured specimens to detect the presence of antibodies to Andes virus (ANDV) through Strip Immunoblot Assay (SIA), and of viral genome by RT-PCR. The results consistently showed that the karyotype of southern Patagonia specimens was 2n = 56, equal to that of O. longicaudatus, and that individuals from this area do not differentiate phylogenetically from those of the northern range of distribution. In addition, the serology showed the presence of antibodies IgG anti-ANDV and of viral genome in heart, kidney, spleen, and lungs of a single specimen of Oligoryzomys from the locality of Fuerte Bulnes in the Magallanes region. We conclude that all specimens trapped south of 51° S correspond to Oligoryzomys longicaudatus, thus expanding the distribution of this specie! from 51° to at least 55° S. The results also extended the disiribution of the Andes strain of Hantavirus to southernmost Patagonia.<br>Actualmente se reconocen 20 especies de Oligoryzomys (Rodentia, Sigmodontinae) en la región Neotropical, la mayoría de ellas distinguidas por sus cariotipos, los que fluctúan entre 46-70 cromosomas. En Chile se reconocen dos especies, Oligoryzomys longicaudatus (Bennet, 1832; "colilargo"; 2n = 56), desde los 27° S hasta aproximadamente 51° S, y Oligoryzomys magellanicus (Bennet, 1836; 2n = 54), al sur de los 51 ° S en la región Patagónica de Chile y Argentina. Como parte de una investigación en curso en la Patagonia sur de Chile, reportamos los resultados de muéstreos de pequeños mamíferos en seis localidades. Cariotipamos 28 especímenes y secuenciamos la región hipervariable I del mtDNA en 22 individuos, alineando estas secuencias con una filogenia de O. longicaudatus en desarrollo. Adicionalmente evaluamos la serología y la presencia de carga viral en todos los especímenes capturados con el objeto de detectar la presencia de anticuerpos anti-Andesvirus (ANDV) mediante Strip Immunoblot Assay (SIA), y de genoma viral mediante RT-PCR. Los resultados muestran consistentemente que el cariotipo de los especímenes de la Patagonia sur de Chile es 2n = 56, similar al de O. longicaudatus, y que los individuos de esta región no se diferencian filogenéticamente de aquellos del norte del rango de distribución de esta especie. Adicionalmente, los análisis serológicos demostraron la presencia de anticuerpos IgG anti-ANDV y de genoma viral en corazón, riñon, bazo y pulmones de un espécimen de Oligoryzomys de la localidad de Fuerte Bulnes en la Región de Magallanes. Concluimos que todos los especímenes capturados al sur de los 51° S corresponden a Oligoryzomys longicaudatus, expandiendo así el rango de distribución de esta especie hasta al menos 55° S. Los resultados también extienden la distribución de la cepa Andes de Hantavirus al extremo sur de la Patagonia