Development of reverse genetic tools to study Chapare and Machupo viruses.

Arenaviruses are highly pathogenic viruses that pose a serious public health threat. Chapare virus (CHAV) and Machupo virus (MACV), two New World arenaviruses, cause hemorrhagic fevers with case fatality rates of up to 45%. Research on therapeutic drug targets and vaccines for these viruses is limited because biosafety level 4 containment is required for handling them. In this study, we developed reverse genetics systems, including minigenomes and recombinant viruses, that will facilitate the study of these pathogens. The minigenome system is based on the S segment of CHAV or MACV genomes expressing the fluorescent reporter gene ZsGreen (ZsG). We also generated recombinant CHAV and MACV with and without the ZsG reporter gene. As a proof-of-concept study, we used both minigenomes and recombinant viruses to test the inhibitory effects of previously reported antiviral compounds. The new reverse genetics system described here will facilitate future therapeutic studies for these two life-threatening arenaviruses.

Presencia de Oligoryzomys microtis (Rodentia) en hábitats silvestres en Bolivia / Presence of Oligoryzomys microtis (Rodentia) in wild habitats in Bolivia

Rodents are very important organisms within ecosystems; however, some species are considered pests because they consume and damage crops and because they are vectors, hosts, or reservoirs in the transmission of emerging infectious diseases. Rodents in Bolivia are represented by 148 species, Oligoryzomys microtis (Allen, 1916) being a species of public health importance because it is considered a potential natural reservoir of the Chapare virus, which causes Chapare Hemorrhagic Fever, and it is a deadly disease for humans. Its impact on public health is still unknown. The present study consisted of recording the presence of the species O. microtis through the use of Sherman-type live capture traps for small mammals arranged in linear transects in the wild and intervened habitats of the Samuzabety community, where the Chapare virus was detected for the first time, this community is located in the Chapare Province of the department of Cochabamba, Bolivia. The species recorded were the rodents Oligoryzomys microtis (morphotype matogrossae), Proechimys brevicauda, Neacomys vargasllosai, Hylaeamys perenensis, and the marsupial Metachiurus nudicaudatus. The presence of the species O. microtis (morphotype matogrossae) in the community of Samuzabety is confirmed. This species is associated with forest habitats with nearby and surrounding crops. The species O. microtis has epidemiological relevance as it is the natural reservoir of the Río Mamoré Hantavirus and is currently considered a potential reservoir of the Chapare virus and other Arenaviruses.

Los roedores son organismos muy importantes dentro de los ecosistemas; sin embargo, algunas especies son consideradas como plagas porque consumen y dañan cultivos y porque son vectores, hospederos o reservorios en la trasmisión de enfermedades infecciosas emergentes. Los roedores en Bolivia están representados por 148 especies, entre las cuales Oligoryzomys microtis (Allen, 1916) es una especie de importancia en salud pública, debido a que es considerada como potencial reservorio natural del virus Chapare, el cual produce la fiebre hemorrágica Chapare, enfermedad mortal para el ser humano y con un impacto en la salud pública aún desconocido. En este estudio se registró la presencia de la especie O. microtis?/i>, mediante el uso de trampas de captura viva tipo Sherman para pequeños mamíferos dispuestas en transectos lineales, en los hábitats silvestres e intervenidos de la comunidad de Samuzabety, sitio en el que se detectó por primera vez el virus Chapare. Esta comunidad se encuentra ubicada en la Provincia Chapare del departamento de Cochabamba, Bolivia. Las especies registradas fueron los roedores Oligoryzomys microtis (morfotipo matogrossae), Proechimys brevicauda, Neacomys vargasllosai, Hylaeamys perenensis y el marsupial Metachiurus nudicaudatus. Se confirma la presencia de la especie O. microtis (morfotipo matogrossae) en la comunidad de Samuzabety, la cual se encuentra asociada con hábitats de bosques, con cultivos cercanos y a su alrededor. La especie O. microtis tiene relevancia epidemiológica al ser el reservorio natural del hantavirus Río Mamoré y al ser considerado actualmente como potencial reservorio del virus Chapare y de otros arenavirus.

Fiebre hemorrágica Chapare: una enfermedad zoonótica emergente producto de la expansión agrícola / Chapare hemorrhagic fever: an emerging zoonotic disease as a result of agricultural expansion

Chapare hemorrhagic fever is an emerging zoonotic disease caused by a Mammarenavirus, of the Arenaviridae family, called Chapare virus. Its name refers to the region in which it first appeared. This virus is transmitted through direct contact with the excreta of wild rodents that interact with humans by invading homes close to a rural area and when humans enter the jungle for various reasons such as agriculture and tourism, among others. This virus has been classified by the World Health Organization as biosafety level IV, where pathogens with the highest risk for humans are included and for which there are no vaccines available. It produces a febrile and hemorrhagic picture that leads to death two weeks after the onset of symptoms. There is no vaccine or standardized treatment to treat this disease. The bio ecological aspects of the reservoir are not known, nor are the factors that could be related to the emergency in the area. An investigation should be carried out focused mainly on knowing the circulation of the Chapare virus in the Bolivian tropics, knowing the bioecological characteristics of the reservoir to produce and contribute with reliable information for the design of future surveillance and control strategies with community participation, as well as to strengthen laboratory diagnostic capacities in health establishments in the municipality of Villa Tunari.

La fiebre hemorrágica Chapare es una enfermedad zoonótica emergente causada por un Mammarenavirus de la familia Arenaviridae, llamado virus Chapare; su nombre se debe a la región en la cual apareció por primera vez. Este virus es transmitido por medio del contacto directo con las excretas de los roedores silvestres que interactúan con el ser humano, al invadir las viviendas que se encuentran cercanas al área silvestre y cuando el hombre incursiona a la selva por diversas razones, como las actividades de agricultura o turismo, entre otras. Este virus ha sido catalogado por la Organización Mundial de la Salud como nivel de bioseguridad IV, en el cual se ubican los patógenos de mayor riesgo para el ser humano y para los cuales no existen vacunas disponibles. Produce un cuadro febril y hemorrágico que lleva al fallecimiento a las dos semanas de haber iniciado los síntomas. No existe vacuna ni tratamiento estandarizado para tratar esta enfermedad, no se conocen los aspectos bioecológicos del reservorio y tampoco los factores que podrían estar relacionados con la emergencia en la zona. Se deberá realizar una investigación enfocada principalmente en conocer la circulación del virus Chapare en la región del trópico boliviano, conocer las características bioecológicas del reservorio con el propósito de producir y aportar con información fehaciente para el diseño de futuras estrategias de vigilancia y control con participación comunitaria, así como fortalecer las capacidades de diagnóstico de laboratorio en los establecimientos de salud del municipio de Villa Tunari.

Codon usage signatures in Sabia and Chapare for host adaptation.

Sabia and Chapare viruses in the Arenavirus family cause viral hemorrhagic fever among humans with a fatality rate of 30% with no treatment models. Therefore, it is of interest to document the codon usage, amino acid patterns and associated factors influencing the observed variations in Sabia and Chapare viruses for host adaptation. Multivariate statistical analysis revealed compositional constraint and host selection pressure influencing the viral codon usage patterns. These data suggests the codon usage signatures in Sabia and Chapare viruses for host adaptation in the human host implying its role in the rapid progression of the infection. Dinucleotides UpG and CpA were noted to be over-represented among the Sabia, Chapare viruses and human genomes. Strong restraint from the usage of CpG dinucleotides among viruses is linked with the molecular mimicry of the human immune system. Thus, the data reported from this study help in understanding the mechanism of viral adaptation inside the host genome for further consideration in drug discovery.

Clinical features of fatal cases of Chapare virus hemorrhagic fever originating from rural La Paz, Bolivia, 2019: A cluster analysis.

INTRODUCTION: In 2003 an emerging mammarenavirus (formerly arenaviruses) was discovered in Bolivia and named Chapare (CHAPV). It was associated with severe and fatal hemorrhagic fever, being similar in clinical features to Machupo (MACV). In mid-2019, CHAPV was the cause of a cluster of five cases, two of them laboratory confirmed, three of them fatal. Here, we report the main clinical findings, epidemiological features and the potential ecological aspects, of that cluster of cases in rural La Paz, Bolivia. METHODS: For this observational, retrospective and cross-sectional study, information was obtained from the Hospitals and the Ministry of Health for the cases that were laboratory-diagnosed and related, during 2019. RT-PCR was used for the detection of the RNA of CHAPV in the blood samples. RESULTS: Two cases were RT-PCR + for CHAPV. The median age of patients was 42 y-old (IQR 25-45), four out of five were male. All patients were hospitalized, admitted to the ICU and had fever, upper digestive hemorrhage, with two of them, presenting ARDS, and requiring mechanical ventilation. Three patients died (case fatality rate, CFR 60%). CONCLUSIONS: Mammarenaviruses led to a high fatality rate. These cases occurred in areas with suitable ecoepidemiological conditions for rodent-borne diseases, including CHAPV infection. Socioenvironmental and occupational factors in rural areas of Bolivia may contribute with the risk of zoonotic spillover and transmission to humans.