An Open One-Step RT-qPCR for SARS-CoV-2 detection

The COVID-19 pandemic has resulted in millions of deaths globally, and while several diagnostic systems were proposed, real-time reverse transcription polymerase chain reaction (RT-PCR) remains the gold standard. However, diagnostic reagents, including enzymes used in RT-PCR, are subject to centralized production models and intellectual property restrictions, which present a challenge for less developed countries. With the aim of generating a standardized One-Step open RT-qPCR protocol to detect SARS-CoV-2 RNA in clinical samples, we purified and tested recombinant enzymes and a non-proprietary buffer. The protocol utilized M-MLV RT and Taq DNA pol enzymes to perform a Taqman probe-based assay. Synthetic RNA samples were used to validate the One-Step RT-qPCR components, demonstrating sensitivity comparable to a commercial kit routinely employed in clinical settings for patient diagnosis. Further evaluation on 40 clinical samples (20 positive and 20 negative) confirmed its comparable diagnostic accuracy. This study represents a proof of concept for an open approach to developing diagnostic kits for viral infections and diseases, which could provide a cost-effective and accessible solution for less developed countries.

An Open One-Step RT-qPCR for SARS-CoV-2 detection

The COVID-19 pandemic has resulted in millions of deaths globally, and while several diagnostic systems were proposed, real-time reverse transcription polymerase chain reaction (RT-PCR) remains the gold standard. However, diagnostic reagents, including enzymes used in RT-PCR, are subject to centralized production models and intellectual property restrictions, which present a challenge for less developed countries. With the aim of generating a standardized One-Step open RT-qPCR protocol to detect SARS-CoV-2 RNA in clinical samples, we purified and tested recombinant enzymes and a non-proprietary buffer. The protocol utilized M-MLV RT and Taq DNA pol enzymes to perform a Taqman probe-based assay. Synthetic RNA samples were used to validate the One-Step RT-qPCR components, and the kit showed comparable sensitivity to approved commercial kits. The One-Step RT-qPCR was then tested on clinical samples and demonstrated similar performance to commercial kits in terms of positive and negative calls. This study represents a proof of concept for an open approach to developing diagnostic kits for viral infections and diseases, which could provide a cost-effective and accessible solution for less developed countries.

Infection with SARS-CoV-2 variant Gamma (P.1) in Chile increased ICU admission risk three to five-fold

The 2021 wave of SARS-CoV-2 infection in Chile was characterized by an explosive increase in ICU admissions, which disproportionately affected individuals younger than 60 years. This second wave was also accompanied by an explosive increase in Gamma (P.1) variant detections and the massive vaccine rollout. We unveil the role the Gamma variant played in stressing the use of critical care, by developing and calibrating a queueing model that uses data on new onset cases and actual ICU occupancy, symptom's onset to ICU admission interval, ICU length-of-stay, genomic surveillance, and vaccine effectiveness. Our model shows that infection with the Gamma (P.1) variant led to a 3.5-4.7-fold increase in ICU admission for people younger than 60 years. This situation occurred on top of the already reported higher infection rate of the Gamma variant. Importantly, our results also strongly suggest that the vaccines used in Chile (inactivated mostly, but also an mRNA), were able to curb Gamma variant ICU admission over infections.

Autoantibodies against type I IFNs in patients with critical influenza pneumonia

Autoantibodies neutralizing type I interferons (IFNs) can underlie critical COVID-19 pneumonia and yellow fever vaccine disease. We report here on 13 patients harboring autoantibodies neutralizing IFN-α2 alone (five patients) or with IFN-ω (eight patients) from a cohort of 279 patients (4.7%) aged 6-73 yr with critical influenza pneumonia. Nine and four patients had antibodies neutralizing high and low concentrations, respectively, of IFN-α2, and six and two patients had antibodies neutralizing high and low concentrations, respectively, of IFN-ω. The patients' autoantibodies increased influenza A virus replication in both A549 cells and reconstituted human airway epithelia. The prevalence of these antibodies was significantly higher than that in the general population for patients <70 yr of age (5.7 vs. 1.1%, P = 2.2 × 10-5), but not >70 yr of age (3.1 vs. 4.4%, P = 0.68). The risk of critical influenza was highest in patients with antibodies neutralizing high concentrations of both IFN-α2 and IFN-ω (OR = 11.7, P = 1.3 × 10-5), especially those <70 yr old (OR = 139.9, P = 3.1 × 10-10). We also identified 10 patients in additional influenza patient cohorts. Autoantibodies neutralizing type I IFNs account for ∼5% of cases of life-threatening influenza pneumonia in patients <70 yr old.

Comparison of VSV Pseudovirus and Focus Reduction Neutralization Assays for Measurement of Anti-Andes orthohantavirus Neutralizing Antibodies in Patient Samples

Andes orthohantavirus (ANDV) is the etiologic agent of hantavirus cardiopulmonary syndrome (HCPS), which has a case fatality rate around 35%, with no effective treatment or vaccine available. ANDV neutralizing antibody (NAb) measurements are important for the evaluation of the immune response following infection, vaccination, or passive administration of investigational monoclonal or polyclonal antibodies. The standard assay for NAb measurement is a focus reduction neutralization test (FRNT) featuring live ANDV and must be completed under biosafety level (BSL)-3 conditions. In this study, we compared neutralization assays featuring infectious ANDV or vesicular stomatitis virus (VSV) pseudovirions decorated with ANDV glycoproteins for their ability to measure anti-ANDV NAbs from patient samples. Our studies demonstrate that VSV pseudovirions effectively measure NAb from clinical samples and have greater sensitivity compared to FRNT with live ANDV. Importantly, the pseudovirus assay requires less labor and sample materials and can be conducted at BSL-2.

[Consensus of infectious complications in patients treated with selected biological therapies: first Part]

The use of biological therapies has meant a great improvement in the management of several conditions like autoimmune, neoplastic or others diseases. Although its use has implied significant improvements in the prognosis of these diseases, it is not exempt from complications: infectious diseases as one of them. The objective of this consensus was to evaluate, from an infectious viewpoint, the safeness of the most frequently used biological therapies and give recommendations for the prevention of infections in patients treated with these drugs. These recommendations were based on the highest quality evidence available for the selected biologics. The consensus counts of two manuscripts. This first part details the risks of developing infectious complications depending on the type of biological used for a certain pathology. This evaluation included a broad search in MEDLINE and Epistemonikos of systematic reviews and meta-analyzes of controlled clinical trials and casecontrol examining post-treatment infections with anti-TNF alpha, anti-CD20, anti-CD52, CTLA4-Ig and anti-integrins. The research was complemented by a review of: multicentre cohorts of biological users, the MMWR of the CDC, Atlanta, U.S.A., and national registers and scientific societies in which infectious complications derived from the use of biological therapies were mentioned.

[Consensus of infectious complications in patients treated with selected biological therapies.Screening of hepatitis B in high risk Chilean and immigrant pregnant women: Management of mother to child transmission Second part: Chilean Guidelines for Prevention of Infections associated to use of Biological Therapies (PREVITEB)]

The use of biological therapies has meant a great improvement in the management of several conditions like autoimmune, neoplastic or others diseases. Although its use has implied significant improvements in the prognosis of these diseases, it is not exempt from complications: infectious diseases as one of them. The objective of this consensus was to evaluate, from an infectious viewpoint, the safeness of the most frequently used biological therapies and give recommendations for the prevention of infections in patients treated with these drugs. These recommendations were based on the highest quality evidence available for the selected biologics. The consensus counts of 2 manuscripts. This second part is a guideline that details these recommendations through screening strategies, prophylactic therapies and vaccines indications for bacterial, mycobacterial, viral, fungal and parasitic infections, both for adults and children.

[Basic requirements of facilities for hospitals that treat hemato-oncological patients: hospital environment, diagnostic protocols and therapeutic arsenal]

The care of cancer patients, including recipients of hematopoietic stem cell transplantation, has numerous challenges for hospitals that must provide safe environments in which exposure to pathogens that generate morbidity and mortality is reduced at maximum. At the same time, they must have established protocols that allow a rational study of the possible infectious etiologies and the existence of an adequate therapeutic arsenal together with timely treatment algorithms, updated according to consensus guidelines and effective according to the suspected or confirmed infection. This article introduces some of the arguments that support these requirements, then that are developed in three successive articles dedicated to the hospital environment, diagnostic protocols and therapeutic arsenal.

2502. Host Susceptibility to Andes Hantavirus Infection Associates to a Single Nucleotide Polymorphism at the αVβ3 Integrin

Background

Methods

Results

Conclusion

Disclosures

1264. Healthcare-Acquired Influenza in Critical Ill Patients

Background

Healthcare-associated infections (HAIs) increases morbidity and mortality. During 2014, at Hospital Clínico Red de Salud UC CHRISTUS (RS-UCCH), was estimated that 15% of viral respiratory infections were acquired during hospitalization, and influenza was the main etiologic agent. The aim of this study was to obtain clinical characterization of HAIs due to influenza virus in patients hospitalized in critical care units (CCU) and special care units (chronic patients who need hospitalized nurse care).

Methods

Descriptive study of CCU and special care patients with hospital acquired influenza during 2014–2017. HAI due to influenza was defined as: symptoms onset and/or positive influenza PCR ≥48 hours after hospital admission, without previous respiratory symptoms or with negative PCR.

Results

22 patients with median age of 74 years old were identified, only three pediatric cases. The average time of acquired influenza was at 13th day of hospitalization. In 77% Influenza A was the only agent detected and 27% had respiratory co-infection. Thirteen (59%) were previously hospitalized in CCU, but only 2 (15%) due to respiratory problems. Nineteen patients (86%) presented comorbidity such as arterial hypertension (59%), chronic kidney disease (18%), and immunosuppression (18%). Half of them had a decompensation, mainly respiratory, associated to influenza infection. The observed lethality was 18%. Among all the influenza HAI, 59% occurred in unvaccinated patients, although 46% of them met criteria for vaccination recommendation.

Conclusion

HAI due to influenza occurred in chronic, older, and unvaccinated patients. Education about HAIs and continuing high vaccination coverage must be a priority.

Disclosures

All authors: No reported disclosures.

2485. Circulating T Follicular Helper Cells and Immune Response Induced by Influenza Vaccine in Children With Acute Lymphoblastic Leukemia During Maintenance Therapy

Background

Vaccine immune response is impaired in cancer patients. Follicular helper T lymphocytes (cTfh) are essential for high affinity and long lasting humoral response. The objective of this study was to evaluate the role of cTfh in the immune response induced by influenza vaccine in children with acute lymphoblastic leukemia (ALL).

Methods

Children with ALL in maintenance therapy and a control group of healthy children were included. Blood samples were taken on the day of vaccination (D0), and on day 28 (D28). The humoral response was evaluated by haemagglutination inhibition test and frequency of cTfh was studied by flow cytometry.

Results

Twenty-four children with ALL and 8 healthy children were included: 67 and 38% were women, median age of 5 years old in both groups. A 33% (8/24) of patients and 63% (5/8) of controls were seroprotected at D28. Seroprotected children at D28 were significantly older than non-protected ones (10 and 3.6 years respectively, P = 0,004). During follow-up, three children with ALL had influenza infection. An increase of percentage of cTfh cells from D0 to D28 was observed in both groups, but it was significant only in ALL patients (average for ALL, D0-D28: 18–23%, P = 0.003 and average for controls, D0-D28: 22–26%). No differences were found between seroprotected and non-seroprotected children in cTfh cell at D0 or D28. The increase of percentage of cTfh cells from D0 to D28 was observed in both groups, it was significant only in non-seroprotected subjects (average for seroprotected, D0-D28: 21–24% and average for non-seroprotected, D0-D28: 18–24%, P = 0.004).

Conclusion

Children with ALL achieved a lower seroprotection than healthy children. After vaccination, both groups had an increase of cTfh cells. We did not found an association between the percentage of cTfh cells and seroprotection at D28. The association between the lack of humoral response and cTfh dysfunction should be evaluated in further studies (We report public funding from Fondecyt grant Nº 11150970).

Disclosures

All authors: No reported disclosures.

Hantavirus cardiopulmonary syndrome successfully treated with high-volume hemofiltration

Hantavirus cardiopulmonary syndrome has a high mortality rate, and early connection to extracorporeal membrane oxygenation has been suggested to improve outcomes. We report the case of a patient with demonstrated Hantavirus cardiopulmonary syndrome and refractory shock who fulfilled the criteria for extracorporeal membrane oxygenation and responded successfully to high volume continuous hemofiltration. The implementation of high volume continuous hemofiltration along with protective ventilation reversed the shock within a few hours and may have prompted recovery. In patients with Hantavirus cardiopulmonary syndrome, a short course of high volume continuous hemofiltration may help differentiate patients who can be treated with conventional intensive care unit management from those who will require more complex therapies, such as extracorporeal membrane oxygenation.

Defining the antibody cross-reactome directed against the influenza virus surface glycoproteins

Influenza virus infections induce antibodies against the viral surface glycoproteins hemagglutinin and neuraminidase, and these responses can be broadly protective. To test the breadth and magnitude of antibody responses, mice, guinea pigs and ferrets were sequentially infected with divergent H1N1 or H3N2 viruses. Antibody responses were measured by ELISA against an extensive panel of recombinant glycoproteins representing the viral diversity in nature. Guinea pigs developed high titers of broadly cross-reactive antibodies; mice and ferrets exhibited narrower humoral responses. Then, we compared antibody responses after H1N1 or H3N2 infections in humans and found markedly broad responses and cogent evidence for original antigenic sin. This work will inform universal influenza vaccine design and can guide pandemic preparedness efforts against emerging influenza viruses.

Molecular method for the detection of Andes hantavirus infection: validation for clinical diagnostics

Hantavirus cardiopulmonary syndrome is a severe disease caused by exposure to New World hantaviruses. Early diagnosis is difficult due to the lack of specific initial symptoms. Antihantavirus antibodies are usually negative until late in the febrile prodrome or the beginning of cardiopulmonary phase, while Andes hantavirus (ANDV) RNA genome can be detected before symptoms onset. We analyzed the effectiveness of quantitative reverse transcription polymerase chain reaction (RT-qPCR) as a diagnostic tool detecting ANDV-Sout genome in peripheral blood cells from 78 confirmed hantavirus patients and 166 negative controls. Our results indicate that RT-qPCR had a low detection limit (~10 copies), with a specificity of 100% and a sensitivity of 94.9%. This suggests the potential for establishing RT-qPCR as the assay of choice for early diagnosis, promoting early effective care of patients, and improving other important aspects of ANDV infection management, such as compliance of biosafety recommendations for health personnel in order to avoid nosocomial transmission.

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.

Infection of human monocyte-derived dendritic cells by ANDES Hantavirus enhances pro-inflammatory state, the secretion of active MMP-9 and indirectly enhances endothelial permeability

Background

Andes virus (ANDV), a rodent-borne Hantavirus, is the major etiological agent of Hantavirus cardiopulmonary syndrome (HCPS) in South America, which is mainly characterized by a vascular leakage with high rate of fatal outcomes for infected patients. Currently, neither specific therapy nor vaccines are available against this pathogen. ANDV infects both dendritic and epithelial cells, but in despite that the severity of the disease directly correlates with the viral RNA load, considerable evidence suggests that immune mechanisms rather than direct viral cytopathology are responsible for plasma leakage in HCPS. Here, we assessed the possible effect of soluble factors, induced in viral-activated DCs, on endothelial permeability. Activated immune cells, including DC, secrete gelatinolytic matrix metalloproteases (gMMP-2 and -9) that modulate the vascular permeability for their trafficking.

Methods

A clinical ANDES isolate was used to infect DC derived from primary PBMC. Maturation and pro-inflammatory phenotypes of ANDES-infected DC were assessed by studying the expression of receptors, cytokines and active gMMP-9, as well as some of their functional status. The ANDES-infected DC supernatants were assessed for their capacity to enhance a monolayer endothelial permeability using primary human vascular endothelial cells (HUVEC).

Results

Here, we show that in vitro primary DCs infected by a clinical isolate of ANDV shed virus RNA and proteins, suggesting a competent viral replication in these cells. Moreover, this infection induces an enhanced expression of soluble pro-inflammatory factors, including TNF-α and the active gMMP-9, as well as a decreased expression of anti-inflammatory cytokines, such as IL-10 and TGF-β. These viral activated cells are less sensitive to apoptosis. Moreover, supernatants from ANDV-infected DCs were able to indirectly enhance the permeability of a monolayer of primary HUVEC.

Conclusions

Primary human DCs, that are primarily targeted by hantaviruses can productively be infected by ANDV and subsequently induce direct effects favoring a proinflammatory phenotype of infected DCs. Finally, based on our observations, we hypothesize that soluble factors secreted in ANDV-infected DC supernatants, importantly contribute to the endothelial permeability enhancement that characterize the HCPS.

[Presence of mutations associated with ganciclovir resistance in cytomegalovirus UL97 gene]

BACKGROUND

Long term use of ganciclovir (GCV) is associated with acquired resistance to it. Ninety percent of the responsible mutations occur in cytomegalovirus (CMV) UL 97 gene.

AIM

To search for these mutations, comparing nucleotide sequences of CMV-positive samples from post transplant and immunocompromised patients receiving GCV, with sequences of CMV isolates obtained from subjects not exposed to the drug.

PATIENTS AND METHODS

Codons 440 to 465 of gene UL 97, including the most common mutations causing resistance to GCV, were amplified in 33 plasma samples from patients exposed to GCV and in 15 urine samples of newborns. Both populations and their nucleotide sequences were compared with the prototype strain CMV AD169.

RESULTS

Samples of exposed patients had multiple mutations but only one had a mutation associated with clinical resistance (M460I). Eight subjects had the D605E mutation, whose role in resistance is controversial. The remaining 150 mutations were silent mutations.

CONCLUSIONS

A low frequency of mutations associated with CMV resistance to GCV was found in these exposed and unexposed samples. These mutations may reflect coexistence of multiple genetic variants of CMV. The absence of clinical expression of resistance, even with these mutations, can be explained by the use of GCV for a shorter lapse than that associated with the appearance of resistance.

Prospective Evaluation of Household Contacts of Persons with Hantavirus Cardiopulmonary Syndrome in Chile

BACKGROUND

Andes virus (ANDV) infection, which has a case fatality rate of 37% in Chile, often occurs in household clusters and may be transmitted from person to person.

METHODS

To determine the incidence and risk factors for additional household cases, we conducted a prospective study among recent household contacts of persons with hantavirus cardiopulmonary syndrome (HCPS) in Chile, including testing of serum for anti-hantavirus antibodies and blood cells for ANDV RNA by reverse-transcription polymerase chain reaction (RT-PCR).

RESULTS

We enrolled 76 index case patients and 476 household contacts, of whom 16 (3.4%) developed HCPS; 32.6% of 92 cases occurred in household clusters. The risk of HCPS was 17.6% among sex partners of index case patients, versus 1.2% among other household contacts (P<.001). Person-to-person transmission was definite in 3, probable in 9, and possible in 2 of the 16 additional household case patients. We detected ANDV RNA by RT-PCR in peripheral blood cells 5-15 days before the onset of symptoms or the appearance of anti-hantavirus antibodies.

CONCLUSIONS

In recent household contacts of persons with HCPS in Chile, the risk of HCPS was greatest among sex partners. Among the household contacts who developed HCPS, viremia preceded the onset of symptoms and the appearance of anti-hantavirus antibodies by up to 2 weeks.

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.

Prevalence of antibodies to hantavirus among family and health care worker contacts of persons with hantavirus cardiopulmonary syndrome: lack of evidence for nosocomial transmission of Andes virus to health care workers in Chile

Nosocomial transmission of Andes virus has been documented in Argentina, but has not yet been proven in Chile. We studied 215 contacts (106 family member contacts and 109 health care worker contacts) of 20 index cases of hantavirus cardiopulmonary syndrome (HCPS) in Chile. The seroprevalence of IgG antibodies against Andes virus was 1.9% (95% confidence interval [CI] = 0.34-6.3%) among the family members and 0.0% (95% CI = 0-3.2%) among the health care workers. Our data suggest that there is no evidence for nosocomial transmission of Andes virus in region IX of Chile.