Hantavirus pulmonary syndrome in a highly endemic area of Brazil

Seroprevalence of Hantavirus among Manual Cane Cutters and Epidemiological Aspects of HPS in Central Brazil

Hantavirus pulmonary syndrome (HPS) is a rodent-borne zoonotic disease that is endemic throughout the Americas. Agricultural activities increase exposure to wild rodents, especially for sugarcane cutters. We carried out a survey of the epidemiological aspects of HPS and investigated the prevalence of hantavirus infection in the sugarcane cutter population from different localities in the Brazilian Midwest region. We conducted a retrospective study of all confirmed HPS cases in the state of Goiás reported to the National HPS surveillance system between 2007 and 2017, along with a seroepidemiological study in a population of sugarcane cutters working in Goiás state in 2016, using the anti-hantavirus (Andes) ELISA IgG. A total of 634 serum samples from cane cutters were tested for hantavirus antibodies, with 44 (6.9%) being IgG-reactive according to ELISA. The destination of garbage was the only statistically significant variable (p = 0.03) related to the detection of hantavirus IgG (p < 0.05). We described the epidemiological profile of reported hantavirus cases in Goiás-a highly endemic area for HPS, and where the seroepidemiological study was conducted. Our results increase our knowledge about hantavirus infections in Brazil and highlight the vulnerability of sugarcane cutters to a highly lethal disease that, to date, has no specific treatment or vaccination.

Deep Sequencing to Reveal Phylo-Geographic Relationships of Juquitiba Virus in Paraguay

Several hantaviruses result in zoonotic infections of significant public health concern, causing hemorrhagic fever with renal syndrome (HFRS) or hantavirus cardiopulmonary syndrome (HCPS) in the Old and New World, respectively. Given a 35% case fatality rate, disease-causing New World hantaviruses require a greater understanding of their biology, genetic diversity, and geographical distribution. Juquitiba hantaviruses have been identified in Oligoryzomys nigripes in Brazil, Paraguay, and Uruguay. Brazil has reported the most HCPS cases associated with this virus. We used a multiplexed, amplicon-based PCR strategy to screen and deep-sequence the virus harbored within lung tissues collected from Oligoryzomys species during rodent field collections in southern (Itapúa) and western (Boquerón) Paraguay. No Juquitiba-like hantaviruses were identified in Boquerón. Herein, we report the full-length S and M segments of the Juquitiba hantaviruses identified in Paraguay from O. nigripes. We also report the phylogenetic relationships of the Juquitiba hantaviruses in rodents collected from Itapúa with those previously collected in Canindeyú. We showed, using the TN93 nucleotide substitution model, the coalescent (constant-size) population tree model, and Bayesian inference implemented in the Bayesian evolutionary analysis by sampling trees (BEAST) framework, that the Juquitiba virus lineage in Itapúa is distinct from that in Canindeyú. Our spatiotemporal analysis showed significantly different time to the most recent ancestor (TMRA) estimates between the M and S segments, but a common geographic origin. Our estimates suggest the additional geographic diversity of the Juquitiba virus within the Interior Atlantic Forest and highlight the need for more extensive sampling across this biome.

Orthohantavirus Survey in Indigenous Lands in a Savannah-Like Biome, Brazil

In Brazil, the first confirmed cases of hantavirus cardiopulmonary syndrome in Indigenous populations occurred in 2001. The purpose of this study was to determine the seroprevalence of orthohantavirus infections in the Utiariti Indigenous land located in the southeastern region of the Brazilian Amazon. In December 2014 and 2015, a survey was conducted using an enzyme-linked immunosorbent assay in nine villages belonging to the Haliti–Paresí Indigenous communities. A total of 301 participants were enrolled in the study. Of the two study cohorts, the one from 2014 showed a prevalence of 12.4%, whereas the one from 2015 had a serum prevalence of 13.4%. Analysis of the paired samples of 110 Indigenous people who participated in both stages of the study enabled identification of four individuals who had seroconverted during the study period. Identifying the circulation of orthohantaviruses in the Utiariti Indigenous land highlights a serious public health problem in viral expansion and highlights the need to implement preventive measures appropriate to the sociocultural reality of these communities.

Serum Markers Associated with Severity and Outcome of Hantavirus Pulmonary Syndrome

Background

Hantavirus pulmonary syndrome (HPS) is caused by Andes virus (ANDV) and related hantaviruses in the Americas. Despite a fatality rate of 40%, the pathogenesis of HPS is poorly understood and factors associated with severity, fatality, and survival remain elusive.

Methods

Ninety-three ANDV-infected HPS patients, of whom 34 had a fatal outcome, were retrospectively studied. Serum levels of cytokines and other inflammation-associated markers were analyzed using multiplex immunoassay and enzyme-linked immunosorbent assay. Associations with disease severity, fatal outcome, and survival were identified using logistic regression.

Results

HPS patients exhibited increased serum levels of markers associated with inflammation, intestinal damage, and microbial translocation compared to controls. Patients with fatal outcome displayed higher levels of interleukin (IL) 6, IL-10, interferon-γ, soluble tumor necrosis factor-related apoptosis-inducing ligand, and intestinal fatty acid–binding protein (I-FABP) than survivors. Levels of complement factor 5/5a were higher in survivors compared with fatal cases. IL-6 and I-FABP, the latter a marker for intestinal damage, were by multivariate analyses identified as independent markers associated with disease severity (odds ratio [OR], 2.25; 95% confidence interval [CI], 1.01–5.01) and fatal outcome (OR, 1.64; 95% CI, 1.01–2.64), respectively.

Conclusions

HPS patients displayed a multifaceted, systemic inflammatory response, with IL-6 and I-FABP as independent markers of disease severity and fatality, respectively.

Hantavirus pulmonary syndrome in children: case report and case series from an endemic area of Brazil

Hantavirus Cardiopulmonary Syndrome (HCPS) is an important emergent zoonosis associated with wild rodents in Brazil, where this viral infection in children is generally rare. We present HCPS in a child from the Pantanal Biome and a review of all reported pediatric cases in Mato Grosso State, an endemic area for HCPS in Brazil. The investigation used the Information System for Notifiable Diseases database (SINAN). A 12-year-old boy was hospitalized with fever and respiratory failure and hantavirus IgM and IgG antibodies were detected by ELISA in serum samples. During the period of 1999 to 2016, 32 HCPS pediatric cases confirmed by serology were reported to SINAN with a mortality rate of 34.4%. The possibility of hantavirus infection in children with acute febrile illness associated with respiratory failure should be considered mainly in recognized endemic areas as Mato Grosso State, contradicting a hypothesis that children are more protected from lung involvement.

Sobrevida de pessoas com hantavirose diagnosticadas no Estado do Paraná, Brasil

Resumo: Hantavirose é uma doença emergente e com impacto na saúde pública. Por apresentar sinais e sintomas inespecíficos e facilmente confundidos com outras doenças, seu prognóstico poderia ser melhorado por meio do conhecimento de fatores que pudessem contribuir para seu desfecho. O estudo objetivou identificar os fatores associados ao tempo de sobrevivência em pessoas com hantavirose. Trata-se de um estudo com casos confirmados de hantavirose de janeiro/1992 a junho/2016 do Estado do Paraná, Brasil. Cada caso apresentou dois desfechos competitivos possíveis: óbito ou cura. Para a análise de sobrevivência foi utilizado um modelo de riscos competitivos e as probabilidades dos desfechos estimadas pelo estimador de Aalen-Johansen. A medida de associação foi a razão de riscos (RzRiscos), com respectivos intervalos de 95% de confiança (IC95%). Dos 280 indivíduos com hantavirose, 107 (38,21%) evoluíram para o óbito, 161 (57,5%) para a cura e 12 (4,29%) foram censurados. O modelo final de sobrevivência foi composto por uso de respirador mecânico para o óbito (RzRiscos = 2,86; IC95%: 1,76-4,64; p = 0,00002), sinais hemorrágicos para o óbito (RzRiscos = 2,86; IC95%: 1,69-4,84; p = 0,00009) e para a cura (RzRiscos = 0,66; IC95%: 0,45-0,95; p = 0,03), cefaleia para a cura (RzRiscos = 1,99; IC95%: 1,12-3,54; p = 0,02) e menor de 20 anos para a cura (RzRiscos = 1,73; IC95%: 1,05-2,84; p = 0,03). Sinais hemorrágicos e uso de respirador mecânico são fatores relacionados com a gravidade dos casos e não oportunizam tempo suficiente para reverter o desfecho. No entanto, esses sinais de gravidade corroboram o argumento da importância da suspeição oportuna, permitindo um manejo clínico adequado a fim de reduzir a letalidade.

Hantaviruses and a neglected environmental determinant

Most human pathogenic hantaviruses cause severe hemorrhagic fevers with a high rate of fatalities, such as occurs due to the genotypes causing hantavirus cardiopulmonary syndrome carried by the New World Sigmodontinae and Neotominae rodents. An increasing number of outbreaks and the possibility of cases spreading over international borders have led to greater interest in these viruses and the environmental determinants that facilitate their transmission. Rodents, shrews, moles and bats act as reservoir hosts of hantaviruses, and within the hantavirus transmission flow, the prevalence and distribution of infection in reservoir hosts is influenced by a range of factors. Climate change and landscape alteration affect hantavirus transmission, but the outcomes can differ among different hantaviruses and for the same virus in differentbiomes. However, it is evident that the underlying mechanisms that mediate hantavirus transmission are largely unknown, so that much work remains to be done regarding the transmission dynamics of hantaviruses. Overall, our review highlights the importance of examining interactions over several trophic levels and the underlying mechanisms (density and trait-mediated indirect effects) linking predation risk and hantavirus transmission, to develop an ecological framework to understand disease in natural, preserved and degraded systems.

Prediction of Pan-Specific B-Cell Epitopes From Nucleocapsid Protein of Hantaviruses Causing Hantavirus Cardiopulmonary Syndrome

Hantaviruses are emerging viral pathogens that causes hantavirus cardiopulmonary syndrome (HCPS) in the Americas, a severe, sometimes fatal, respiratory disease in humans with a case fatality rate of ≥50%. IgM and IgG-based serological detection methods are the most common approaches used for laboratory diagnosis of hantaviruses. Such emerging viral pathogens emphasizes the need for improved rapid diagnostic devices and vaccines incorporating pan-specific epitopes of genotypes. We predicted linear B-cell epitopes for hantaviruses that are specific to genotypes causing HCPS in humans using in silico prediction servers. We modeled the Andes and Sin Nombre hantavirus nucleocapsid protein to locate the identified epitopes. Based on the mean percent prediction probability score, epitope IMASKSVGS/TAEEKLKKKSAF was identified as the best candidate B-cell epitope specific for hantaviruses causing HCPS. Promiscuous epitopes were identified in the C-terminal of the protein. Our study for the first time has reported pan-specific B-cell epitopes for developing immunoassays in the detection of antibodies to hantaviruses causing HCPS. Identification of epitopes with pan-specific recognition of all genotypes causing HCPS could be valuable for the development of immunodiagnositic tools toward pan-detection of hantavirus antibodies in ELISA. J. Cell. Biochem. 118: 2320-2324, 2017. © 2017 Wiley Periodicals, Inc.

Viral Lower Respiratory Tract Infections

Lower respiratory tract infections in children are often viral in origin. Unfortunately in this time of significant antimicrobial resistance of infectious organisms, especially bacteria, there is still a tendency for clinicians to manage a child who coughs with antibiotics. In addition, the World Health Organization (WHO) has defined “pneumonia” as a condition that only occurs in children who have “fast breathing or chest wall indrawing”. That would delineate upper respiratory tract infections from those in the lower airway. However, in addition to pneumonia another important entity exists in the lower respiratory tract that is almost always viral in origin. This condition is acute viral bronchiolitis. The concept of “acute lower respiratory tract infection” (ALRTI) has emerged and it is becoming increasing evident from a number of studies that the infectious base of both acute pneumonia (AP) and acute bronchiolitis in children has a mixed etiology of microorganisms. Therefore, whilst certain clinical phenotypes do not require antibiotics the actual microbial etiology is much less distinct.

Mechanistic Insight into Bunyavirus-Induced Membrane Fusion from Structure-Function Analyses of the Hantavirus Envelope Glycoprotein Gc

Hantaviruses are zoonotic viruses transmitted to humans by persistently infected rodents, giving rise to serious outbreaks of hemorrhagic fever with renal syndrome (HFRS) or of hantavirus pulmonary syndrome (HPS), depending on the virus, which are associated with high case fatality rates. There is only limited knowledge about the organization of the viral particles and in particular, about the hantavirus membrane fusion glycoprotein Gc, the function of which is essential for virus entry. We describe here the X-ray structures of Gc from Hantaan virus, the type species hantavirus and responsible for HFRS, both in its neutral pH, monomeric pre-fusion conformation, and in its acidic pH, trimeric post-fusion form. The structures confirm the prediction that Gc is a class II fusion protein, containing the characteristic β-sheet rich domains termed I, II and III as initially identified in the fusion proteins of arboviruses such as alpha- and flaviviruses. The structures also show a number of features of Gc that are distinct from arbovirus class II proteins. In particular, hantavirus Gc inserts residues from three different loops into the target membrane to drive fusion, as confirmed functionally by structure-guided mutagenesis on the HPS-inducing Andes virus, instead of having a single "fusion loop". We further show that the membrane interacting region of Gc becomes structured only at acidic pH via a set of polar and electrostatic interactions. Furthermore, the structure reveals that hantavirus Gc has an additional N-terminal "tail" that is crucial in stabilizing the post-fusion trimer, accompanying the swapping of domain III in the quaternary arrangement of the trimer as compared to the standard class II fusion proteins. The mechanistic understandings derived from these data are likely to provide a unique handle for devising treatments against these human pathogens.