Molecular epidemiological investigation of Mayaro virus in febrile patients from Goiania City, 2017-2018

Current challenges in the discovery of treatments against Mayaro fever

INTRODUCTION

Mayaro fever is an emerging viral disease that manifests as an acute febrile illness. The disease is self-limiting, however joint pain can persist for months leading to chronic arthralgia. There is no specific treatment available, which ultimately leads to socioeconomic losses in populations at risk as well as strains to the public health systems.

AREAS COVERED

We reviewed the candidate treatments proposed for Mayaro virus (MAYV) infection and disease, including antiviral compounds targeting viral or host mechanisms, and pathways involved in disease development and pathogenicity. We assessed compound screening technologies and experimental infection models used in these studies and indicated the advantages and limitations of available technologies and intended therapeutic strategies.

EXPERT OPINION

Although several compounds have been suggested as candidate treatments against MAYV infection, notably those with antiviral activity, most compounds were assessed only in vitro. Compounds rarely progress toin vivo or preclinical studies, and such difficulty may be associated with limited experimental models. MAYV biology is largely inferred from related alphaviruses and reflected by few studies focusing on target proteins or mechanisms of action for MAYV. Therapeutic strategies targeting pathogenic inflammatory responses have shown potential against MAYV-induced disease in vivo, which might reduce long-term sequelae.

Cryptic circulation of chikungunya virus in São Jose do Rio Preto, Brazil, 2015-2019

BACKGROUND

Chikungunya virus (CHIKV) has spread across Brazil with varying incidence rates depending on the affected areas. Due to cocirculation of arboviruses and overlapping disease symptoms, CHIKV infection may be underdiagnosed. To understand the lack of CHIKV epidemics in São José do Rio Preto (SJdRP), São Paulo (SP), Brazil, we evaluated viral circulation by investigating anti-CHIKV IgG seroconversion in a prospective study of asymptomatic individuals and detecting anti-CHIKV IgM in individuals suspected of dengue infection, as well as CHIKV presence in Aedes mosquitoes. The opportunity to assess two different groups (symptomatic and asymptomatic) exposed at the same geographic region aimed to broaden the possibility of identifying the viral circulation, which had been previously considered absent.

METHODOLOGY/PRINCIPAL FINDINGS

Based on a prospective population study model and demographic characteristics (sex and age), we analyzed the anti-CHIKV IgG seroconversion rate in 341 subjects by ELISA over four years. The seroprevalence increased from 0.35% in the first year to 2.3% after 3 years of follow-up. Additionally, we investigated 497 samples from a blood panel collected from dengue-suspected individuals during the 2019 dengue outbreak in SJdRP. In total, 4.4% were positive for anti-CHIKV IgM, and 8.6% were positive for IgG. To exclude alphavirus cross-reactivity, we evaluated the presence of anti-Mayaro virus (MAYV) IgG by ELISA, and the positivity rate was 0.3% in the population study and 0.8% in the blood panel samples. In CHIKV and MAYV plaque reduction neutralization tests (PRNTs), the positivity rate for CHIKV-neutralizing antibodies in these ELISA-positive samples was 46.7%, while no MAYV-neutralizing antibodies were detected. Genomic sequencing and phylogenetic analysis revealed CHIKV genotype ECSA in São José do Rio Preto, SP. Finally, mosquitoes collected to complement human surveillance revealed CHIKV positivity of 2.76% of A. aegypti and 9.09% of A. albopictus (although it was far less abundant than A. aegypti) by RT-qPCR.

CONCLUSIONS/SIGNIFICANCE

Our data suggest cryptic CHIKV circulation in SJdRP detected by continual active surveillance. These low levels, but increasing, of viral circulation highlight the possibility of CHIKV outbreaks, as there is a large naïve population. Improved knowledge of the epidemiological situation might aid in outbreaks prevention.

Lessons from a Multilaboratorial Task Force for Diagnosis of a Fatal Toxoplasmosis Outbreak in Captive Primates in Brazil

Toxoplasmosis is an important zoonotic disease caused by the parasite Toxoplasma gondii and is especially fatal for neotropical primates. In Brazil, the Ministry of Health is responsible for national epizootic surveillance, but some diseases are still neglected. Here, we present an integrated investigation of an outbreak that occurred during the first year of the COVID-19 pandemic among eleven neotropical primates housed at a primatology center in Brazil. After presenting non-specific clinical signs, all animals died within four days. A wide range of pathogens were evaluated, and we successfully identified T. gondii as the causative agent within four days after necropsies. The liver was the most affected organ, presenting hemorrhage and hepatocellular necrosis. Tachyzoites and bradyzoite cysts were observed in histological examinations and immunohistochemistry in different organs; in addition, parasitic DNA was detected through PCR in blood samples from all specimens evaluated. A high prevalence of Escherichia coli was also observed, indicating sepsis. This case highlights some of the obstacles faced by the current Brazilian surveillance system. A diagnosis was obtained through the integrated action of researchers since investigation for toxoplasmosis is currently absent in national guidelines. An interdisciplinary investigation could be a possible model for future epizootic investigations in animals.

A geopositioned and evidence-graded pan-species compendium of Mayaro virus occurrence

Mayaro Virus (MAYV) is an emerging health threat in the Americas that can cause febrile illness as well as debilitating arthralgia or arthritis. To better understand the geographic distribution of MAYV risk, we developed a georeferenced database of MAYV occurrence based on peer-reviewed literature and unpublished reports. Here we present this compendium, which includes both point and polygon locations linked to occurrence data documented from its discovery in 1954 until 2022. We describe all methods used to develop the database including data collection, georeferencing, management and quality-control. We also describe a customized grading system used to assess the quality of each study included in our review. The result is a comprehensive, evidence-graded database of confirmed MAYV occurrence in humans, non-human animals, and arthropods to-date, containing 262 geo-positioned occurrences in total. This database - which can be updated over time - may be useful for local spill-over risk assessment, epidemiological modelling to understand key transmission dynamics and drivers of MAYV spread, as well as identification of major surveillance gaps.

Report of natural Mayaro virus infection in Mansonia humeralis (Dyar & Knab, Diptera: Culicidae)

BACKGROUND

Arboviruses are a group of viruses transmitted to vertebrate hosts by certain blood-feeding arthropods. Among urban vectors of arboviruses, mosquitoes of the genus Aedes are the most common. However, other mosquitoes may be susceptible to infection and involved in the transmission, such as Mansonia spp. Therefore, this study aimed to investigate whether Mansonia humeralis can be infected with the Mayaro virus (MAYV).

METHODS

These insects were collected from 2018 to 2020 in chicken coops of rural communities in Jaci Paraná in Porto Velho, Rondônia, Brazil, while performing blood-feeding on roosters. The mosquitoes were randomly grouped in pools from which the head and thorax were macerated and checked for the presence of MAYV by quantitative reverse transcription polymerase chain reaction (RT-qPCR). The positive pools were used to infect the C6/36 cell line, and on different days post-infection, the supernatant of the infected cells was subjected to viral detection by RT-qPCR.

RESULTS

A total of 183 pools of female mosquitoes were tested, of which 18% were positive for MAYV; some samples from insect pools inoculated into C6/36 cells showed in vitro multiplication capacity between 3 and 7 days post-infection.

CONCLUSIONS

This is the first report of Ma. humeralis mosquitoes that are naturally infected by MAYV, indicating that these vectors may be potential transmitting agents of this arbovirus.

Retrospective molecular investigation of Mayaro and Oropouche viruses at the human-animal interface in West-central Brazil, 2016-2018

Mayaro virus (MAYV, Togaviridae) and Oropouche orthobunyavirus (OROV, Peribunyaviridae) are emerging enzootic arboviruses in Latin America. Outbreaks of febrile illness associated with MAYV and OROV have been reported among humans mainly in the northern region of Brazil since the 1980s, and recent data suggest these viruses have circulated also in more populated areas of western Brazil. MAYV shares mosquito vectors with yellow fever virus and it has been historically detected during yellow fever epidemics. Aiming to investigate the transmission of OROV and MAYV at the human-animal interface during a yellow fever, chikungunya and Zika outbreaks in Brazil, we conducted a retrospective molecular investigation in 810 wild and domestic animals, 106 febrile patients, and 22.931 vectors collected from 2016 to 2018 in Cuiaba and Campo Grande metropolitan regions, western Brazil. All samples tested negative for OROV and MAYV RNA by RT-qPCR. Findings presented here suggest no active circulation of MAYV and OROV in the sampled hosts. Active surveillance and retrospective investigations are instrumental approaches for the detection of cryptic and subclinical activity of enzootic arboviruses and together serve as a warning system to implement appropriate actions to prevent outbreaks.

Mayaro Virus: The State-of-the-Art for Antiviral Drug Development

Mayaro virus is an emerging arbovirus that causes nonspecific febrile illness or arthralgia syndromes similar to the Chikungunya virus, a virus closely related from the Togaviridae family. MAYV outbreaks occur more frequently in the northern and central-western states of Brazil; however, in recent years, virus circulation has been spreading to other regions. Due to the undifferentiated initial clinical symptoms between MAYV and other endemic pathogenic arboviruses with geographic overlapping, identification of patients infected by MAYV might be underreported. Additionally, the lack of specific prophylactic approaches or antiviral drugs limits the pharmacological management of patients to treat symptoms like pain and inflammation, as is the case with most pathogenic alphaviruses. In this context, this review aims to present the state-of-the-art regarding the screening and development of compounds/molecules which may present anti-MAYV activity and infection inhibition.

Re-emergence of mayaro virus and coinfection with chikungunya during an outbreak in the state of Tocantins/Brazil

OBJECTIVE

To perform a molecular screening to detect infections by the mayaro virus and possible coinfections with Chikungunya during an outbreak in the state of Tocantins/Brazil in 2017.

RESULTS

Of a total 102 samples analyzed in this study, 6 cases were identified with simultaneous infection between mayaro and chikungunya viruses (5.88%). In these 6 samples, the mean Cycle threshold (Ct) for CHIKV was 26.87 (SD ± 10.54) and for MAYV was 29.58 (SD ± 6.34). The mayaro sequences generated showed 95-100% identity to other Brazilian sequences of this virus and with other MAYV isolates obtained from human and arthropods in different regions of the world. The remaining samples were detected with CHIKV monoinfection (41 cases), DENV monoinfection (50 cases) and coinfection between CHIKV/DENV (5 cases). We did not detect MAYV monoinfections.