Viral shedding and viraemia of Andes virus during acute hantavirus infection: a prospective study.

BACKGROUND: Andes virus (ANDV) is a zoonotic Orthohantavirus leading to hantavirus cardiopulmonary syndrome. Although most transmissions occur through environmental exposure to rodent faeces and urine, rare person-to-person transmission has been documented, mainly for close contacts. This study investigates the presence and infectivity of ANDV in body fluids from confirmed cases and the duration of viraemia. METHODS: In this prospective study, 131 participants with confirmed ANDV infection were enrolled in Chile in a prospective study between 2008 and 2022. Clinical samples (buffy coat, plasma, gingival crevicular fluid [GCF], saliva, nasopharyngeal swabs [NPS], and urine) were collected weekly for 3 weeks together with clinical and epidemiological data. Samples were categorised as acute or convalescent (up to and after 16 days following onset of symptoms). Infectivity of positive fluids was assessed after the culture of samples on Vero E6 cells and use of flow cytometry assays to determine the production of ANDV nucleoprotein. FINDINGS: ANDV RNA was detected in 100% of buffy coats during acute phase, declining to 95% by day 17, and to 93% between days 23-29. ANDV RNA in GCF and saliva decreased from 30% and 12%, respectively, during the acute phase, to 12% and 11% during the convalescent phase. Successful infectivity assays of RT-qPCR-positive fluids, including GCF, saliva, NPS, and urine, were observed in 18 (42%) of 43 samples obtained during the acute phase of infection. After re-culture, the capacity to infect Vero E6 cells was maintained in 16 (89%) of 18 samples. Severity was associated with the presence of ANDV RNA in one or more fluids besides blood (odds ratio 2·58 [95% CI 1·42-5·18]). INTERPRETATION: ANDV infection is a systemic and viraemic infection, that affects various organs. The presence of infectious particles in body fluids contributes to our understanding of potential mechanisms for person-to-person transmission, supporting the development of preventive strategies. Detection of ANDV RNA in additional fluids at hospital admission is a predictor of disease severity. FUNDING: None. TRANSLATION: For the Spanish translation of the abstract see Supplementary Materials section.

Functional Dysconnectivity in Ventral Striatocortical Systems in 22q11.2 Deletion Syndrome.

22q11.2 deletion syndrome (22q11.2DS) is a genetic neurodevelopmental disorder that represents one of the greatest known risk factors for psychosis. Previous studies in psychotic subjects without the deletion have identified a dopaminergic dysfunction in striatal regions, and dysconnectivity of striatocortical systems, as an important mechanism in the emergence of psychosis. Here, we used resting-state functional MRI to examine striatocortical functional connectivity in 22q11.2DS patients. We used a 2 × 2 factorial design including 125 subjects (55 healthy controls, 28 22q11.2DS patients without a history of psychosis, 10 22q11.2DS patients with a history of psychosis, and 32 subjects with a history of psychosis without the deletion), allowing us to identify network effects related to the deletion and to the presence of psychosis. In line with previous results from psychotic patients without 22q11.2DS, we found that there was a dorsal to ventral gradient of hypo- to hyperstriatocortical connectivity related to psychosis across both patient groups. The 22q11.2DS was additionally associated with abnormal functional connectivity in ventral striatocortical networks, with no significant differences identified in the dorsal system. Abnormalities in the ventral striatocortical system observed in these individuals with high genetic risk to psychosis may thus reflect a marker of illness risk.

Abnormal nodal and global network organization in resting state functional MRI from subjects with the 22q11 deletion syndrome.

The 22q11 deletion syndrome is a genetic disorder associated with a high risk of developing psychosis, and is therefore considered a neurodevelopmental model for studying the pathogenesis of schizophrenia. Studies have shown that localized abnormal functional brain connectivity is present in 22q11 deletion syndrome like in schizophrenia. However, it is less clear whether these abnormal cortical interactions lead to global or regional network disorganization as seen in schizophrenia. We analyzed from a graph-theory perspective fMRI data from 40 22q11 deletion syndrome patients and 67 healthy controls, and reconstructed functional networks from 105 brain regions. Between-group differences were examined by evaluating edge-wise strength and graph theoretical metrics of local (weighted degree, nodal efficiency, nodal local efficiency) and global topological properties (modularity, local and global efficiency). Connectivity strength was globally reduced in patients, driven by a large network comprising 147 reduced connections. The 22q11 deletion syndrome network presented with abnormal local topological properties, with decreased local efficiency and reductions in weighted degree particularly in hub nodes. We found evidence for abnormal integration but intact segregation of the 22q11 deletion syndrome network. Results suggest that 22q11 deletion syndrome patients present with similar aberrant local network organization as seen in schizophrenia, and this network configuration might represent a vulnerability factor to psychosis.

Targeted high volume hemofiltration could avoid extracorporeal membrane oxygenation in some patients with severe Hantavirus cardiopulmonary syndrome.

BACKGROUND: Hantavirus cardiopulmonary syndrome (HCPS) has a high lethality. Severe cases may be rescued by venoarterial extracorporeal membrane oxygenation (VA ECMO), alongside substantial complications. High volume hemofiltration (HVHF) is a depurative technique that provides homeostatic balance allowing hemodynamic stabilization in some critically ill patients. METHODS: We implemented HVHF before VA ECMO consideration in the last five severe HCPS patients requiring mechanical ventilation and vasoactive drugs admitted to our intensive care unit. Patients were considered HVHF-responders if VA ECMO was avoided and HVHF-nonresponders if VA ECMO support was needed despite HVHF. A targeted-HVHF strategy compounded by aggressive hyperoncotic albumin, sodium bicarbonate, and calcium supplementation plus ultrafiltration to avoid fluid overload was implemented on three patients. RESULTS: Patients had maximum serum lactate of 8.8 (8.7-12.8) mmol/L and a lowest cardiac index of 1.8 (1.8-1.9) L/min/m2 . The first two required VA ECMO. They were connected later to HVHF, displayed progressive tachycardia and declining stroke volume. The opposite was true for HVHF-responders who received targeted-HVHF. All patients survived, but one of the VA ECMO patients suffered a vascular complication. CONCLUSION: HVHF may contribute to support severe HCPS patients avoiding the need for VA ECMO in some. Early connection and targeted-HVHF may increase the chance of success.

Platelet Count in Patients with Mild Disease at Admission is Associated with Progression to Severe Hantavirus Cardiopulmonary Syndrome.

BACKGROUND: Hantavirus cardiopulmonary syndrome (HCPS) has a mortality up to 35-40% and its treatment is mainly supportive. A variable to predict progression from mild to severe disease is unavailable. This study was performed in patients with documented infection by Andes orthohantavirus, and the aim was to find a simple variable to predict progression to moderate/severe HCPS in patients with mild disease at admission. METHODS: We performed a retrospective analysis of 175 patients between 2001 and 2018. Patients were categorized into mild, moderate, and severe disease according to organ failure and advanced support need at hospital admission (e.g., mechanical ventilation, vasopressors). Progression to moderate/severe disease was defined accordingly. Clinical and laboratory variables associated with progression were explored. RESULTS: Forty patients with mild disease were identified; 14 of them progressed to moderate/severe disease. Only platelet count was different between those who progressed versus those that did not (37 (34-58) vs. 83 (64-177) K/mm3, p < 0.001). A ROC curve analysis showed an AUC = 0.889 (0.78-1.0) p < 0.001, with a platelet count greater than 115K /mm3 ruling out progression to moderate/severe disease. CONCLUSIONS: In patients with mild disease at presentation, platelet count could help to define priority of evacuation to tertiary care centers.

Deletions in Genes Participating in Innate Immune Response Modify the Clinical Course of Andes Orthohantavirus Infection.

Andes orthohantavirus (ANDV) is an important human pathogen causing hantavirus cardiopulmonary syndrome (HCPS) with a fatality rate of 30% in Chile. Around 60% of all cases have a severe clinical course, while the others have a mild clinical course. The main goal of this study was to understand if the genetic variation of patients is associated with the clinical course they develop after ANDV infection. For this, the frequency of copy number variants (CNVs, i.e., deletions and duplications) was studied in 195 patients, 88 with mild and 107 with severe HCPS. CNVs were called from intensity data of the Affymetrix Genome-Wide SNP Array 6.0. The analysis of the data was performed with PennCNV, ParseCNV and R softwares; Results: a deletion of 19, 416 bp in the q31.3 region of chromosome 1 is found more frequently in severe patients (p < 0.05). This region contains Complement Factor H Related (CFHR1) and CFHR3 genes, regulators of the complement cascade. A second deletion of 1.81 kb located in the p13 region of chr20 was significantly more frequent in mild patients (p < 0.05). This region contains the SIRPB1 gene, which participates in the innate immune response, more specifically in neutrophil trans-epithelial migration. Both deletions are associated with the clinical course of HCPS, the first being a risk factor and the second being protective. The participation of genes contained in both deletions in ANDV infection pathophysiology deserves further investigation.

Knowledge, attitudes, and practices regarding hantavirus disease and acceptance of a vaccine trial in rural communities of southern Chile.

Andes hantavirus cardiopulmonary syndrome, transmitted by Oligoryzomys longicaudatus, has no approved treatment, a case fatality rate of 35%, and documented person-to-person transmission. An Andes vaccine, highly needed for prevention, is in development. We aimed to evaluate knowledge, attitudes and practices (KAP) regarding hantavirus disease and willingness to participate in a future Andes vaccine trials through a cross sectional face-to-face oral survey of a randomly selected adult sample from 2 rural communes in southern Chile. Human subjects approval was obtained from our institutional IRBs, and participants signed informed consent. We enrolled 319 subjects from Corral and 321 from Curarrehue; 98% had heard about hantavirus disease and its reservoir but only half knew about transmission, symptoms and prevention. Participants fear the disease but are only partially aware of their own risk. One third of participants reported presence of rodents inside their homes. Despite moderate confidence in their health system, most subjects perceived vaccines as beneficial, and 93% would accept an approved hantavirus vaccine. Half would agree to participate in a vaccine trial and 29% would allow their children to participate. Motivations to participate were mainly altruistic, while risk perception was the main reason for declining. Knowledge about hantavirus disease and prevention practices require reinforcement, and a vaccine trial seems feasible in these populations.

A non-randomized multicentre trial of human immune plasma for treatment of hantavirus cardiopulmonary syndrome caused by Andes virus.

BACKGROUND: In Chile, Andes virus (ANDV) is the sole aetiological agent of hantavirus cardiopulmonary syndrome (HCPS) with mean annual incidence of 55 cases, 32% case fatality rate (CFR) and no specific treatment. Neutralizing antibody (NAb) titres at hospital admission correlate inversely with HCPS severity. We designed an open trial to explore safety and efficacy and evaluate pharmacokinetics of immune plasma as a treatment strategy for this disease. METHODS: We performed plasmapheresis on donors at least 6 months after HCPS and measured NAb titres through a focus-reduction neutralization test. Subjects admitted to 10 study sites with suspected/confirmed HCPS were eligible for treatment with immune plasma by intravenous infusion at an ANDV NAb dose of 5,000 U/kg. HCPS was confirmed through immunoglobulin M serology or reverse transcriptase-PCR. The main outcome was mortality within 30 days. RESULTS: From 2008-2012, we enrolled and treated 32 cases and confirmed HCPS in 29. CFR of hantavirus plasma-treated cases was 4/29 (14%); CFR of non-treated cases in the same period in Chile was 63/199 (32%; P=0.049, OR=0.35, CI=0.12, 0.99); CFR of non-treated cases at the same study sites between 2005-2012 was 18/66 (27%; (P=0.15, OR=0.43, CI=0.14, 1.34) and CFR in a previous methylprednisolone treatment study was 20/60 (33%; P=0.052, OR=0.32, CI=0.10, 1.00). We detected no serious adverse events associated to plasma infusion. Plasma NAb titres reached in recipients were variable and viral load remained stable. CONCLUSIONS: Human ANDV immune plasma infusion appears safe for HCPS. We observed a decrease in CFR in treated cases with borderline significance that will require further studies for confirmation.

High-dose intravenous methylprednisolone for hantavirus cardiopulmonary syndrome in Chile: a double-blind, randomized controlled clinical trial.

BACKGROUND: Andes virus (ANDV)-related hantavirus cardiopulmonary syndrome (HCPS) has a 35% case fatality rate in Chile and no specific treatment. In an immunomodulatory approach, we evaluated the efficacy of intravenous methylprednisolone for HCPS treatment, through a parallel-group, placebo-controlled clinical trial. METHODS: Patients aged >2 years, with confirmed or suspected HCPS in cardiopulmonary stage, admitted to any of 13 study sites in Chile, were randomized by study center in blocks of 4 with a 1:1 allocation and assigned through sequentially numbered envelopes to receive placebo or methylprednisolone 16 mg/kg/day (≤1000 mg) for 3 days. All personnel remained blinded except the local pharmacist. Infection was confirmed by immunoglobulin M antibodies or ANDV RNA in blood. The composite primary endpoint was death, partial pressure of arterial oxygen/fraction of inspired oxygen ratio ≤55, cardiac index ≤2.2, or ventricular tachycardia or fibrillation within 28 days. Safety endpoints included the number of serious adverse events (SAEs) and quantification of viral RNA in blood. Analysis was by intention to treat. RESULTS: Infection was confirmed in 60 of 66 (91%) enrollees. Fifteen of 30 placebo-treated patients and 11 of 30 methylprednisolone-treated patients progressed to the primary endpoint (P = .43). We observed no significant difference in mortality between treatment groups (P = .41). There was a trend toward more severe disease in placebo recipients at entry. More subjects in the placebo group experienced SAEs (P = .02). There were no SAEs clearly related to methylprednisolone administration, and methylprednisolone did not increase viral load. CONCLUSIONS: Although methylprednisolone appears to be safe, it did not provide significant clinical benefit to patients. Our results do not support the use of methylprednisolone for HCPS. CLINICAL TRIALS REGISTRATION: NCT00128180.

Case report: T-cell responses during clearance of Andes virus from blood cells 2 months after severe hantavirus cardiopulmonary syndrome.

Hantavirus Cardiopulmonary Syndrome (HCPS) due to Andes virus (ANDV) is endemic in Chile and Argentina and currently demonstrates a case-fatality rate of 37% in humans. By contrast to the chronically infected rodents, it is believed that ANDV in humans is cleared during the acute phase. Moreover, to date, both magnitude and quality of human T-cell responses during ANDV infection and clearance are unknown. Using IFN-gamma and granzyme B ELISPOT assays as well as flow cytometry, we prospectively studied the ANDV-specific T-cell responses in a 56-year-old convalescing survivor of severe HCPS, whose blood cells remained PCR-positive for ANDV-RNA until day 53 after hospital admission, that is, 67 days after infection and 42 days after discharge. PCR-negativity was closely related to the increase and function of (Gn(46-60))-specific IFN-gamma(+) granzyme B(+) CD8(+) T-cells, but not to neutralizing antibody titers. Concurrently, the phenotype of CD45RA(+)CCR7(-) Gn(46-60)-specific T-cells shifted from a CD28(-)CD27(+) "intermediate" to a CD28(-) CD27(-) "late" effector memory beyond day 53 after hospital admission. This is the first report that shows that ANDV can persist in the human hosts for more than 2 months. Moreover, the kinetics of T-cell responses during ANDV clearance may indicate a major role of T-cells for clearance of ANDV and human immunity to this pathogen.

Neutralizing antibodies in survivors of Sin Nombre and Andes hantavirus infection.

We evaluated titers of homotypic and heterotypic neutralizing antibodies (NAbs) to Andes and Sin Nombre hantaviruses in plasma samples from 20 patients from Chile and the United States. All but 1 patient had high titers of NAb. None of the plasma samples showed high titers against the heterologous virus.