Acute and Delayed Deaths after West Nile Virus Infection, Texas, USA, 2002-2012

Neuroinvasive West Nile virus infections after solid organ transplantation: Single center experience and systematic review

West Nile virus (WNv) is a major cause of viral encephalitis in the United States. WNv infection is usually asymptomatic or a limited febrile illness in the immunocompetent hosts, although a small percentage can develop neuroinvasive disease. Neuroinvasive disease due to WNv in solid organ transplant recipients occurs at higher rates than observed in the general population and can have long term neurological sequalae.

METHODS

We retrospectively reviewed medical records of all solid organ transplant recipients at our institution who tested positive for WNv from 2010 to 2018. Two reviewers performed electronic searches of Medline, Embase, Cochrane Library of literature of WNv infections in SOT. Descriptive statistics were performed on key variables.

RESULTS

Eight recipients (mean age 54, five males) were diagnosed with neuroinvasive WNv infection at our institution. Distribution of infection was as follows: five kidney transplants, one in each kidney-pancreas, liver, and lung. Diagnoses included meningitis (3), encephalitis (1), meningo-encephalitis (4). Median time from transplant to infection was 49.8 months (2.7-175.4). No infections were considered donor-derived. Five patients received treatment with IVIG. Six patients were alive at median follow-up of 49.5 months (21.7-116.8). We identified 29 studies published from 2002 to 2019. Median time from transplant to infection was 14.2 months, with similar allograft distribution; 53% were donor-derived infections.

CONCLUSION

WNv infections in solid organ transplant recipients can be a consequence of organ donation or can be acquired via the community. Infections can be more severe in SOT recipients and lead to neuroinvasive disease.

Virus infection of the CNS disrupts the immune-neural-synaptic axis via induction of pleiotropic gene regulation of host responses

Treatment for many viral infections of the central nervous system (CNS) remains only supportive. Here we address a remaining gap in our knowledge regarding how the CNS and immune systems interact during viral infection. By examining the regulation of the immune and nervous system processes in a nonhuman primate model of West Nile virus neurological disease, we show that virus infection disrupts the homeostasis of the immune-neural-synaptic axis via induction of pleiotropic genes with distinct functions in each component of the axis. This pleiotropic gene regulation suggests an unintended off-target negative impact of virus-induced host immune responses on the neurotransmission, which may be a common feature of various viral infections of the CNS.

Unique Cytokine Response in West Nile Virus Patients Who Developed Chronic Kidney Disease: A Prospective Cohort Study

West Nile virus (WNV) is a widespread and devastating disease, especially in those who develop neuroinvasive disease. A growing body of evidence describes sequelae years after infection, including neurological complications and chronic kidney disease (CKD). Eighty-nine out of 373 WNV-positive cases were followed for approximately two years and compared to 127 WNV-negative controls with and without CKD. Adjusted risk ratios (aRRs) were calculated via a log binomial regression to determine the impact of WNV exposure and other possible confounders on the likelihood of developing CKD. Cytokine profiles of WNV patients and controls were evaluated to characterize differences and describe potential underlying pathophysiological mechanisms. The associated risk for developing CKD was significantly associated with history of WNV infection (aRR = 1.91, 95% CI 1.13–3.25). Additionally, five distinct cytokines were found to be significantly associated with WNV infection (eotaxin, IL-8, IL-12p70, IP-10, and TNFα) after the p-value was adjusted to <0.0019 due to the Bonferroni correction. These data support that WNV infection is an independent risk factor for CKD, even after accounting for confounding comorbidities. WNV participants who developed CKD had high activity of proinflammatory markers, indicating underlying inflammatory disease. This study provides new insights into CKD resultant of WNV infection.

West Nile virus encephalitis: A report of two cases and review of neuroradiological features

West Nile virus (WNV) is a single-stranded RNA arbovirus of Flavivirus genus that is endemic to the United States and known to cause neuroinvasive disease. Diagnosis is confirmed by the presence of WNV-specific IgM antibodies within serum or cerebrospinal fluid (CSF). Radiologically, it presents as hyperintense T2 signal within deep brain structures (ie, thalami and mid-brain) with or without cerebral peduncle and substantia nigra involvement. On diffusion-weighted imaging, restricted diffusion is reported in basal ganglia and disseminated throughout the white matter. In this report, we describe the imaging findings for 2 cases of WNV from our institution; a 56-year-old female and a 34-year-old female. Increased vigilance for WNV is warranted, particularly in immunosuppressed patients presenting with a clinical picture of viral meningoencephalitis despite initial negative magnetic resonance imaging or CSF analysis. A high suspicion for WNV disease should prompt repeat imaging or laboratory workup.

Favipiravir, an anti-influenza drug against life-threatening RNA virus infections

Favipiravir has been developed as an anti-influenza drug and licensed as an anti-influenza drug in Japan. Additionally, favipiravir is being stockpiled for 2 million people as a countermeasure for novel influenza strains. This drug functions as a chain terminator at the site of incorporation of the viral RNA and reduces the viral load. Favipiravir cures all mice in a lethal influenza infection model, while oseltamivir fails to cure the animals. Thus, favipiravir contributes to curing animals with lethal infection. In addition to influenza, favipiravir has a broad spectrum of anti-RNA virus activities in vitro and efficacies in animal models with lethal RNA viruses and has been used for treatment of human infection with life-threatening Ebola virus, Lassa virus, rabies, and severe fever with thrombocytopenia syndrome. The best feature of favipiravir as an antiviral agent is the apparent lack of generation of favipiravir-resistant viruses. Favipiravir alone maintains its therapeutic efficacy from the first to the last patient in an influenza pandemic or an epidemic lethal RNA virus infection. Favipiravir is expected to be an important therapeutic agent for severe influenza, the next pandemic influenza strain, and other severe RNA virus infections for which standard treatments are not available.

Profiling of flaviviral NS2B-NS3 protease specificity provides a structural basis for the development of selective chemical tools that differentiate Dengue from Zika and West Nile viruses

West Nile virus (WNV) and Dengue virus (DENV) are mosquito-borne pathogenic flaviviruses. The NS2B-NS3 proteases found in these viruses are responsible for polyprotein processing and are therefore considered promising medical targets. Another ortholog of these proteases is found in Zika virus (ZIKV). In this work, we applied a combinatorial chemistry approach - Hybrid Combinatorial Substrate Library (HyCoSuL), to compare the substrate specificity profile at the P4-P1 positions of the NS2B-NS3 proteases found in all three viruses. The obtained data demonstrate that Zika and West Nile virus NS2B-NS3 proteases display highly overlapping substrate specificity in all binding pockets, while the Dengue ortholog has slightly different preferences toward natural and unnatural amino acids at the P2 and P4 positions. We used this information to extract specific peptide sequences recognized by the Dengue NS2B-NS3 protease. Next, we applied this knowledge to design a selective substrate and activity-based probe for the Dengue NS2B-NS3 protease. Our work provides a structural framework for the design of inhibitors, which could be used as a lead structure for drug development efforts.

Current Understanding of West Nile Virus Clinical Manifestations, Immune Responses, Neuroinvasion, and Immunotherapeutic Implications

West Nile virus (WNV) is the most common mosquito-borne virus in North America. WNV-associated neuroinvasive disease affects all ages, although elderly and immunocompromised individuals are particularly at risk. WNV neuroinvasive disease has killed over 2300 Americans since WNV entered into the United States in the New York City outbreak of 1999. Despite 20 years of intensive laboratory and clinical research, there are still no approved vaccines or antivirals available for human use. However, rapid progress has been made in both understanding the pathogenesis of WNV and treatment in clinical practices. This review summarizes our current understanding of WNV infection in terms of human clinical manifestations, host immune responses, neuroinvasion, and therapeutic interventions.