Effects of the Natural Flavonoid Quercetin on Arenavirus Junín Infection

There is no specific chemotherapy approved for the treatment of pathogenic arenaviruses that cause severe hemorrhagic fever (HF) in the population of endemic regions in America and Africa. The present study reports the effects of the natural flavonoid quercetin (QUER) on the infection of A549 and Vero cells with Junín virus (JUNV), agent of the Argentine HF. By infectivity assays, a very effective dose-dependent reduction of JUNV multiplication was shown by cell pretreatment at 2-6 h prior to the infection at non-cytotoxic concentrations, with 50% effective concentration values in the range of 6.1-7.5 µg/mL. QUER was also active by post-infection treatment but with minor efficacy. Mechanistic studies indicated that QUER mainly affected the early steps of virus adsorption and internalization in the multiplication cycle of JUNV. Treatment with QUER blocked the phosphorylation of Akt without changes in the total protein expression, detected by Western blot, and the consequent perturbation of the PI3K/Akt pathway was also associated with the fluorescence redistribution from membrane to cytoplasm of TfR1, the cell receptor recognized by JUNV. Then, it appears that the cellular antiviral state, induced by QUER treatment, leads to the prevention of JUNV entry into the cell.

[Argentine hemorrhagic fever: report of two cases in a non-endemic area]

We present the case of a 38-year-old woman with no relevant medical history, resident of the City of Buenos Aires, who was admitted in hospital for presenting fever, retroocular headache, myalgia, arthralgia, and maculopapular pruritic rash on the back of the hands and feet of 6 days of evolution. Laboratory tests revealed lymphopenia, severe thrombocytopenia, and anicteric hepatitis. Her husband had been hospitalized three weeks earlier for a condition of similar characteristics without etiological diagnosis. Subsequently, it evolved with metrorrhagia and axillary petechiae associated with photophobia, drowsiness, and fine tremor of the tongue with normal cerebrospinal fluid, treated with intravenous ceftriaxone 2 g/day for 7 days. Computed tomography of abdomen and pelvis showed a left abdominal wall hematoma. Serological samples were sent to the National Institute of Human Viral Diseases Dr. Julio I. Maiztegui for dengue virus, leptospirosis and hantavirus with non-reactive results, and RT-PCR of Junín virus that was positive. Retrospectively, the spouse was diagnosed by detection of IgG antibodies to Junin virus by ELISA and neutralization tests. Neither of the two cases had a clear epidemiological link. Our aim is to highlight the importance of clinical suspicion outside of endemic areas.

Modulation of the Aryl Hydrocarbon Receptor Signaling Pathway Impacts on Junín Virus Replication

Junín virus (JUNV), a member of the family Arenaviridae, is the etiological agent of the Argentine hemorrhagic fever, an endemic disease in the rural region of Argentina lacking a specific chemotherapy. Aryl hydrocarbon receptor (AHR) is expressed in several mammalian tissues and has been indicated as a sensor of ligands from variable sources and a modulator of the cell immune response. Interestingly, recent studies have suggested that the activation or depression of the AHR signaling pathway may play a role in the outcome of diverse human viral infections. In the present report, the effect of the pharmacological modulation of AHR on JUNV in vitro infection was analyzed. An initial microarray screening showed that the AHR pathway was overexpressed in JUNV-infected hepatic cells. Concomitantly, the infection of Vero and Huh-7 cells with the JUNV strains IV4454 and Candid#1 was significantly inhibited in a dose-dependent manner by treatment with CH223191, a specific AHR antagonist, as detected by infectivity assays, real-time RT-PCR and immunofluorescence detection of viral proteins. Furthermore, the pro-viral role of AHR in JUNV infection appears to be independent of the IFN-I pathway. Our findings support the promising perspectives of the pharmacological modulation of AHR as a potential target for the control of AHF.

South American Hemorrhagic Fevers: A summary for clinicians

OBJECTIVES

This article is one of a series on acute, severe diseases of humans caused by emerging viruses for which there are no or limited licensed medical countermeasures. We approached this summary on South American Hemorrhagic Fevers (SAHF) from a clinical perspective that focuses on pathogenesis, clinical features, and diagnostics with an emphasis on therapies and vaccines that have demonstrated potential for use in an emergency situation through their evaluation in nonhuman primates (NHPs) and/or in humans.

METHODS

A standardized literature review was conducted on the clinical, pathological, vaccine, and treatment factors for SAHF as a group and for each individual virus/disease.

RESULTS

We identified 2 treatments and 1 vaccine platform that have demonstrated potential benefit for treating or preventing infection in humans and 4 other potential treatments currently under investigation.

CONCLUSION

We provide succinct summaries of these countermeasures to give the busy clinician a head start in reviewing the literature if faced with a patient with South American Hemorrhagic Fever. We also provide links to other authoritative sources of information.

Clinical Management of Argentine Hemorrhagic Fever using Ribavirin and Favipiravir, Belgium, 2020

We report a case of Argentine hemorrhagic fever diagnosed in a woman in Belgium who traveled from a disease-endemic area. Patient management included supportive care and combination therapy with ribavirin and favipiravir. Of 137 potential contacts, including friends, relatives, and healthcare and laboratory workers, none showed development of clinical symptoms of this disease.

Innate immune response to arenaviral infection: a focus on the highly pathogenic New World hemorrhagic arenaviruses

Arenaviruses are enveloped, negative-stranded RNA viruses that belong to the family Arenaviridae. This diverse family can be further classified into OW (Old World) and NW (New World) arenaviruses based on their antigenicity, phylogeny, and geographical distribution. Many of the NW arenaviruses are highly pathogenic viruses that cause systemic human infections characterized by hemorrhagic fever and/or neurological manifestations, constituting public health problems in their endemic regions. NW arenavirus infection induces a variety of host innate immune responses, which could contribute to the viral pathogenesis and/or influence the final outcome of virus infection in vitro and in vivo. On the other hand, NW arenaviruses have also developed several strategies to counteract the host innate immune response. We will review current knowledge regarding the interplay between the host innate immune response and NW arenavirus infection in vitro and in vivo, with emphasis on viral-encoded proteins and their effect on the type I interferon response.

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NW arenaviruses induce a variety of host innate immune responses.

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The arenaviruses have several strategies to counteract host innate immune response.

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We review the interplay between host innate immunity and the arenavirus infections.