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Background: The infection caused by Mayaro virus (MAYV), which presents as an acute febrile illness, is considered a neglected tropical disease. The virus is an endemic and emerging pathogen in South America and the Caribbean, responsible for occasional and poorly characterized outbreaks. Currently there is limited information about its expansion and risk areas. Methods: A cross-sectional study was performed in 10 urban primary care health centers in the Cajamarca region of Peru from January to June 2017. A total of 359 patients with suspected febrile illness were assessed. RNA was extracted from serum samples, following which MAYV real-time reverse transcriptase PCR (RT-PCR) for the detection of the nsP1 gene was performed. Results: MAYV was detected in 11.1% (40/359) of samples after RT-PCR amplification and confirmatory DNA sequencing. Most infections were detected in the adult population aged 18–39 years (40%) and 40–59 years (32.5%). Headache was the most frequent symptom in patients with MAYV infection (77.5%), followed by fever (72.5%), myalgia (55.0%), and arthralgia (50.0%). During the study, most of the MAYV cases were seen in May (47.5%) and April (35.0%), corresponding to the dry season (months without rain). Conclusions: This study is novel in describing the presence of MAYV in Cajamarca, an Andean region of Peru. Symptoms are non-specific and can be confused with those of other arbovirus or bacterial infections. Molecular biology methods such as RT-PCR allow the timely and accurate detection of MAYV and could thus be considered as a tool for surveillance in endemic areas. / This research was supported by the Bio & Medical Technology Development Program of the National Research Foundation (NRF) funded by the Korean government (MSIT) (No. 2015M3A9B6073666 ). This study was supported by CONCYTEC Peru , under the contract No 164-2016-FONDECYT, Lima, Peru. Incentive for Research of the Universidad Peruana de Ciencias Aplicadas (No. UPC-C-01-2019), Lima, Peru. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. / Revisión por pares

Arthropod-borne-viruses (arboviruses) pose a global threat due to their ability to be transmitted by hematophagous insects to vertebrate hosts resulting in a range of serious infectious diseases. Sindbis virus (SINV) is the prototype arbovirus of the genus Alphavirus in the family Togaviridae. The purpose of this study was to investigate the use of a fluorescent tagged reporter virus in both in vitro and in vivo environments. The fluorescent protein GFP was inserted between the Capsid and PE2 in the genome of TR339; SINV TaV-GFP (Wm. Klimstra Lab). This virus construct should have the same infectivity and virulence as wild type TR339, leaving a fluorescent ‘path’ in infected cells that may reveal virus transit. Virus stocks were grown in BHK-21 vertebrate cells and C7-10 mosquito cells. Two Aedes albopictus mosquito cell lines, C7-10 and C6/36, were then challenged with vertebrate and mosquito grown reporter virus. Evidence of GFP were seen as early as 6 hours post infection (p.i.) in all samples. Infected C7-10 cells with the vertebrate grown reporter virus were fixed for 1 hour in chilled 4% buffered paraformaldehyde; GFP was shown to be resilient to both fixation and light quenching. Ultimately, Ae. aegypti mosquitoes were challenged with a viremic bloodmeal at a titer of 107 PFU/ml and midguts were dissected over several days. The presence of GFP was observed in midgut columnar epithelial cells as early as day 3 p.i. and remained localized even at day 30 p.i. This is in agreement with published work on the interaction of TR339 in Ae. aegypti gut, signaling this viral construct as a means to visualize wild-type infection.

Sindbis virus (SINV) is an arthropod-borne Alphavirus in the family Togaviridae. Sindbis virus has a broad host range that includes avian, mammalian, and human hosts; therefore, its receptor(s) is/are highly conserved. When the mosquito imbibes a viremic blood meal, the virus infects the midgut cells, disseminates into the hemolymph, and eventually infects the salivary glands. The midgut is an organ of transmission and the virus must overcome the midgut epithelia infection- and escape-barriers. Sindbis virus infection is determined by the chance collision of the glycoproteins with a compatible receptor. Research has supported the involvement of high-affinity laminin receptor and heparan sulfate in SINV binding to host cells. However, it has been suggested that not all strains of SINV are dependent on heparan sulfate for attachment/entry and that SINV could be utilizing multiple receptors. A study using Drosophila demonstrated that, of the nine genes that encode for proteins that enhance SINV infection, only natural resistance-associated macrophage protein (NRAMP) was conserved. A symporter of divalent metals and hydrogen ions, NRAMP is ubiquitously expressed. Overexpression of NRAMP led to an increase in SINV infection of human cells while deletion of NRAMP in mouse and Drosophila decreased SINV infection. Sindbis virus could be utilizing this protein to overcome the infection barriers of mosquito midgut epithelia. In this study, NRAMP was localized to Aedes aegypti and Anopheles quadrimaculatus tissues via immunofluorescence assay and TR339-TaV-eGFP was detected in the midgut epithelia and visceral muscles. We suspect that NRAMP was detected on midguts and/or Malpighian tubules of Aedes aegypti and Anopheles quadrimaculatus. The similarities between the pattern of NRAMP labeling and TR339-TaV-eGFP infection of the midgut suggest that SINV infection is influenced by NRAMP in the midgut epithelia. Because NRAMP is ubiquitously expressed, this research provides insight into the attachment and entry phase of the arbovirus lifecycle.