Bolivian hemorrhagic fever: A narrative review

Treatment of highly virulent mammarenavirus infections-status quo and future directions

INTRODUCTION

Mammarenaviruses are negative-sense bisegmented enveloped RNA viruses that are endemic in Africa, the Americas, and Europe. Several are highly virulent, causing acute human diseases associated with high case fatality rates, and are considered to be significant with respect to public health impact or bioterrorism threat.

AREAS COVERED

This review summarizes the status quo of treatment development, starting with drugs that are in advanced stages of evaluation in early clinical trials, followed by promising candidate medical countermeasures emerging from bench analyses and investigational animal research.

EXPERT OPINION

Specific therapeutic treatments for diseases caused by mammarenaviruses remain limited to the off-label use of ribavirin and transfusion of convalescent sera. Progress in identifying novel candidate medical countermeasures against mammarenavirus infection has been slow in part because of the biosafety and biosecurity requirements. However, novel methodologies and tools have enabled increasingly efficient high-throughput molecular screens of regulatory-agency-approved small-molecule drugs and led to the identification of several compounds that could be repurposed for the treatment of infection with several mammarenaviruses. Unfortunately, most of them have not yet been evaluated in vivo. The most promising treatment under development is a monoclonal antibody cocktail that is protective against multiple lineages of the Lassa virus in nonhuman primate disease models.

A review of emerging health threats from zoonotic New World mammarenaviruses

Despite repeated spillover transmission and their potential to cause significant morbidity and mortality in human hosts, the New World mammarenaviruses remain largely understudied. These viruses are endemic to South America, with animal reservoir hosts covering large geographic areas and whose transmission ecology and spillover potential are driven in part by land use change and agriculture that put humans in regular contact with zoonotic hosts.We compiled published studies about Guanarito virus, Junin virus, Machupo virus, Chapare virus, Sabia virus, and Lymphocytic Choriomeningitis virus to review the state of knowledge about the viral hemorrhagic fevers caused by New World mammarenaviruses. We summarize what is known about rodent reservoirs, the conditions of spillover transmission for each of these pathogens, and the characteristics of human populations at greatest risk for hemorrhagic fever diseases. We also review the implications of repeated outbreaks and biosecurity concerns where these diseases are endemic, and steps that countries can take to strengthen surveillance and increase capacity of local healthcare systems. While there are unique risks posed by each of these six viruses, their ecological and epidemiological similarities suggest common steps to mitigate spillover transmission and better contain future outbreaks.

Chapare virus infection and current perspectives on dentistry

OBJECTIVES

This narrative review addresses relevant points about Chapare virus (CHAV) entry in oral cells, CHAV transmission, and preventive strategies in dental clinical settings. It is critical in dentistry due to the frequent presence of gingival hemorrhage occurred in CHAV-infected patients.

MATERIALS AND METHODS

Studies related to CHAV were searched in MEDLINE/PubMed, Scopus, EMBASE, and Web-of-Science databases without language restriction or year of publication.

RESULTS

Recently, the PAHO/WHO and CDC indicate a presence of human-to-human transmission of CHAV associated with direct contact with saliva, blood, or urine, and also through droplets or aerosols created in healthcare procedures. CHAV was detected in human oropharyngeal saliva and gingival bleeding was confirmed in all cases of CHAV hemorrhagic fever, including evidence of nosocomial CHAV transmission in healthcare workers. We revisited the human transferrin receptor 1 (TfR1) expression in oral, nasal, and salivary glands tissues, as well as, we firstly identified the critical residues in the pre-glycoprotein (GP) complex of CHAV that interacts with human TfR1 using cutting-edge in silico bioinformatics platforms associated with molecular dynamic analysis.

CONCLUSIONS

In this multidisciplinary view, we also point out critical elements to provide perspectives on the preventive strategies for dentists and frontline healthcare workers against CHAV, and in the implementation of salivary diagnostic platforms for virus detection, which can be critical to an urgent plan to prevent human-to-human transmission based on current evidence.

CLINICAL RELEVANCE

The preventive strategies in dental clinical settings are pivotal due to the aerosol-generating procedures in dentistry with infected patients or suspected cases of CHAV infection.

Ophthalmic implications of biological threat agents according to the chemical, biological, radiological, nuclear, and explosives framework

As technology continues to evolve, the possibility for a wide range of dangers to people, organizations, and countries escalate globally. The United States federal government classifies types of threats with the capability of inflicting mass casualties and societal disruption as Chemical, Biological, Radiological, Nuclear, and Energetics/Explosives (CBRNE). Such incidents encompass accidental and intentional events ranging from weapons of mass destruction and bioterrorism to fires or spills involving hazardous or radiologic material. All of these have the capacity to inflict death or severe physical, neurological, and/or sensorial disabilities if injuries are not diagnosed and treated in a timely manner. Ophthalmic injury can provide important insight into understanding and treating patients impacted by CBRNE agents; however, improper ophthalmic management can result in suboptimal patient outcomes. This review specifically addresses the biological agents the Center for Disease Control and Prevention (CDC) deems to have the greatest capacity for bioterrorism. CBRNE biological agents, encompassing pathogens and organic toxins, are further subdivided into categories A, B, and C according to their national security threat level. In our compendium of these biological agents, we address their respective CDC category, systemic and ophthalmic manifestations, route of transmission and personal protective equipment considerations as well as pertinent vaccination and treatment guidelines.

[Recent advances in the development of vaccines against hemorrhagic fevers caused by arenaviruses]

Arenaviruses are a global threat, causing thousands of deaths each year in several countries around the world. Despite strong efforts in the development of vaccine candidates, vaccines against Lassa fever or Bolivian and Venezuelan hemorrhagic fevers are yet to be licensed for a use in humans. In this synthesis, we present the arenaviruses causing fatal diseases in humans and the main vaccine candidates that have been developed over the past decades with an emphasis on the measles-Lassa vaccine, the first Lassa vaccine ever tested in humans, and on the MOPEVAC platform that can potentially be used as a pan-arenavirus vaccine platform.

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.

Etiologies of Zoonotic Tropical Febrile Illnesses That Are Not Part of the Notifiable Diseases in Colombia

In Colombia, tropical febrile illnesses represent one of the most important causes of clinical attention. Febrile illnesses in the tropics are mainly zoonotic and have a broad etiology. The Colombian surveillance system monitors some notifiable diseases. However, several etiologies are not monitored by this system. In the present review, we describe eleven different etiologies of zoonotic tropical febrile illnesses that are not monitored by the Colombian surveillance system but have scientific, historical, and contemporary data that confirm or suggest their presence in different regions of the country: Anaplasma, Arenavirus, Bartonella, relapsing fever group Borrelia, Coxiella burnetii, Ehrlichia, Hantavirus, Mayaro virus, Orientia, Oropouche virus, and Rickettsia. These could generate a risk for the local population, travelers, and immigrants, due to which they should be included in the mandatory notification system, considering their importance for Colombian public health.

Rodent-borne viruses in the region of Middle East

Rodents are one of the most abundant mammal species in the world. They form more than two-fifth of all mammal species and there are approximately 4600 existing rodent species. Rodents are capable of transmitting deadly diseases, especially those that are caused by viruses. Viruses and their consequences have plagued the world for the last two centuries, three pandemics occurred during the last century only. The Middle East is situated at the crossroads of Africa and Asia, along with the Mediterranean Sea and the Indian Ocean, its geographic importance is gained through the diversity of topographies, biosphere, as well as climate aspects that make the region vulnerable to host emerging diseases. Refugee crises also play a major role in expected epidemic outbreaks in the region. Public health has always been the most important priority, and our aim in this review is to raise awareness among public health organisations across the Middle East about the dangers of rodent borne diseases that have been reported or are suspected to be found in the region.

Vaccine Candidates against Arenavirus Infections

The viral family Arenaviridae contains several members that cause severe, and often lethal, diseases in humans. Several highly pathogenic arenaviruses are classified as Risk Group 4 agents and must be handled in the highest biological containment facility, biosafety level-4 (BSL-4). Vaccines and treatments are very limited for these pathogens. The development of vaccines is crucial for the establishment of countermeasures against highly pathogenic arenavirus infections. While several vaccine candidates have been investigated, there are currently no approved vaccines for arenavirus infection except for Candid#1, a live-attenuated Junin virus vaccine only licensed in Argentina. Current platforms under investigation for use include live-attenuated vaccines, recombinant virus-based vaccines, and recombinant proteins. We summarize here the recent updates of vaccine candidates against arenavirus infections.

A MOPEVAC multivalent vaccine induces sterile protection against New World arenaviruses in non-human primates

Pathogenic New World arenaviruses (NWAs) cause haemorrhagic fevers and can have high mortality rates, as shown in outbreaks in South America. Neutralizing antibodies (Abs) are critical for protection from NWAs. Having shown that the MOPEVAC vaccine, based on a hyperattenuated arenavirus, induces neutralizing Abs against Lassa fever, we hypothesized that expression of NWA glycoproteins in this platform might protect against NWAs. Cynomolgus monkeys immunized with MOPEVAC_MAC, targeting Machupo virus, prevented the lethality of this virus and induced partially NWA cross-reactive neutralizing Abs. We then developed the pentavalent MOPEVAC_NEW vaccine, expressing glycoproteins from all pathogenic South American NWAs. Immunization of cynomolgus monkeys with MOPEVAC_NEW induced neutralizing Abs against five NWAs, strong innate followed by adaptive immune responses as detected by transcriptomics and provided sterile protection against Machupo virus and the genetically distant Guanarito virus. MOPEVAC_NEW may thus be efficient to protect against existing and potentially emerging NWAs.

Immunoinformatics Approach to Design Multi-Epitope-Based Vaccine against Machupo Virus Taking Viral Nucleocapsid as a Potential Candidate

The family members of Arenaviridae include members of the genus Machupo virus, which have bi-segmented negative sense RNA inside the envelope and can be transferred to humans through rodent carriers. Machupo virus, a member of the mammarenavirus genus, causes Bolivian hemorrhage fever, its viral nucleocapsid protein being a significant virulence factor. Currently, no treatment is available for Bolivian hemorrhage fever and work to develop a protective as well as post-diagnosis treatment is underway. Adding to these efforts, this study employed a reverse-vaccinology approach to design a vaccine with B and T-cell epitopes of the viral nucleocapsid protein of the Machupo virus. Five B-cell specific, eight MHC-I restricted, and 14 MHC-II restricted epitopes were finalized for the construct based on an antigenicity score of >0.5 and non-allergenicity as a key characteristic. The poly-histidine tag was used to construct an immunogenic and stable vaccine construct and 50S ribosomal 46 protein L7/L12 adjuvant with linkers (EAAAK, GPGPG, and AYY). It covers 99.99% of the world’s population, making it highly efficient. The physicochemical properties like the aliphatic index (118.31) and the GRAVY index (0.302) showed that the vaccine is easily soluble. The overall Ramachandran score of the construct was 90.7%, and the instability index was 35.13, endorsing a stable structure. The immune simulations demonstrated a long-lasting antibody response even after the excretion of the antigen from the body in the first 5 days of injection. The IgM + IgG titers were predicted to rise to 6000 10 days post-injection and were illustrated to be stable (around 3000) after a month, elucidating that the vaccine would be effective and provide enduring protection. Lastly, the molecular interaction between the construct and the IKBKE receptor was significant and a higher eigenfactor value in MD simulations confirmed the stable molecular interaction between the receptor and the vaccine, validating our construct.

Understanding Sabiá virus infections (Brazilian mammarenavirus)

BACKGROUND

Only two naturally occurring human Sabiá virus (SABV) infections have been reported, and those occurred over 20 years ago.

METHODS

We diagnosed two new cases of SABV infection using metagenomics in patients thought to have severe yellow fever and described new features of histopathological findings.

RESULTS

We characterized clinical manifestations, histopathology and analyzed possible nosocomial transmission. Patients presented with hepatitis, bleeding, neurological alterations and died. We traced twenty-nine hospital contacts and evaluated them clinically and by RT-PCR and neutralizing antibodies. Autopsies uncovered unique features on electron microscopy, such as hepatocyte "pinewood knot" lesions. Although previous reports with similar New-World arenavirus had nosocomial transmission, our data did not find any case in contact tracing.

CONCLUSIONS

Although an apparent by rare, Brazilian mammarenavirus infection is an etiology for acute hemorrhagic fever syndrome. The two fatal cases had peculiar histopathological findings not previously described. The virological diagnosis was possible only by contemporary techniques such as metagenomic assays. We found no subsequent infections when we used serological and molecular tests to evaluate close contacts.