Cerebral Venous Thrombosis in Pediatric Age: Risk Factors and Prognosis.

INTRODUCTION: Cerebral venous thrombosis (CVT) is a rare but potentially fatal disease in pediatric age with an important morbimortality. In adults several factors have been associated with worse outcomes, however there are still few studies in children. This study aims to identify risk factors associated with clinical manifestations and long-term sequelae in pediatric CVT. METHODS: Retrospective analysis of pediatric inpatients admitted to a tertiary-care hospital due to CVT between 2008 and 2020. RESULTS: Fifty-four children were included, 56% male, median age of 6.5 years (9 months-17.3 years). Permanent risk factors were identified in 13 patients (malignancy, 8; hematologic condition, 5) and transient risk factors in 47, including head and neck infections (57%) and head trauma (15%). Multiple venous sinuses involvement was present in 65% and the deep venous system was affected in four patients. Seventeen percent had intracranial hemorrhage and 9% cerebral infarction. Sixty-four percent of patients with multiple venous sinuses involvement presented with severe clinical manifestations: impaired consciousness, intracranial hypertension, acute symptomatic seizures or focal deficits. Regarding long-term prognosis, six patients had major sequelae: epilepsy (n = 3), sensory motor deficits (n = 2), and cognitive impairment (n = 3). Permanent risk factors were associated with severe clinical manifestations (p = 0.043). Cerebral infarction and intracranial hemorrhage were associated with major sequelae (p = 0.006 and p = 0.03, respectively, adjusted for age and sex). CONCLUSION: Permanent risk factors, involvement of multiple venous sinuses, intracranial hemorrhage, and cerebral infarction, were related to worse prognosis. Detection and early management of risk factors may limit CVT extension and reduce its morbimortality.

Flexible pseudotyping of retrovirus using recombinase-mediated cassette exchange.

OBJECTIVE: Develop an engineered cell line containing two flexible gene expression systems enabling the continuous production of tailor-made recombinant gammaretrovirus with predictable productivities through targeted integration. RESULTS: Dual-FLEX cells (dFLEX) contain two independent recombinase-mediated cassette exchange (RMCE) systems which confer flexibility to the expression of different transgene and envelope combinations. The flexible envelope expression in dFLEX cells was validated by pseudotyping retrovirus particles with three different viral envelope proteins-GaLV, 4070A and VSV-G. Our results show that dFLEX cells are able to provide high titers of infectious retroviral particles with a single-copy integration of the envelope constructs after RMCE. The integrated CRE/Lox tagging cassette was amenable to express envelope proteins both using constitutive (i.e. CMV) and inducible (i.e. Tet-on) promoters. CONCLUSIONS: dFLEX cell line provides predictable productivities of recombinant retrovirus pseudotyped with different envelope proteins broadening the tropism of particles that can be generated and thus accelerating the research and development of retrovirus-based products.

Enhancing Hepatitis C virus pseudoparticles infectivity through p7NS2 cellular expression.

Hepatitis C pseudoparticles (HCVpp) are used to evaluate HCV cell entry while screening for neutralizing antibodies induced upon vaccination or while screening for new antiviral drugs. In this work we explore the stable production of HCVpp aiming to reduce the variability associated with transient productions. The performance of stably produced HCVpp was assessed by evaluating the influence of Human Serum and the impact of CD81 cellular expression on the infectivity of HCVpp. After evaluating the performance of stably produced HCVpp we studied the effect of co-expressing p7NS2 openreading frame (ORF) on HCVpp infectivity. Our data clearly shows an enhanced infectivity of HCVppp7NS2. Even though the exact mechanism was not completely elucidated, the enhanced infectivity of HCVppp7NS2 is neither a result of an increase production of virus particles nor a result from increased envelope density. The inhibitory effect of p7 inhibitory molecules such as rimantadine suggests a direct contribution of p7 ion channel for the enhanced infectivity of HCVppp7NS2 which is coherent with a pH-dependent cell entry mechanism. In conclusion, we report the establishment of a stable production system of HCVpp with enhanced infectivity through the overexpression of p7NS2 ORF contributing to improve HCV entry assessment assays widely used in antiviral drug discovery and vaccine development.

Canine helper-dependent vectors production: implications of Cre activity and co-infection on adenovirus propagation.

The importance of Cre recombinase to minimize helper vector (HV) contamination during helper-dependent adenovirus vectors (HDVs) production is well documented. However, Cre recombinase, by inducing DNA double-strand breaks (DSBs), can cause a reduced proliferation and genotoxic effects in cultured cells. In this work, Cre-expressing cell stability, co-infection and their relation to adenovirus amplification/HV contamination were evaluated to develop a production protocol for HD canine adenovirus type 2 (CAV-2) vectors. Long-term Cre expression reduced the capacity of MDCK-E1-Cre cells to produce CAV-2 by 7-fold, although cell growth was maintained. High HDV/HV MOI ratio (5:0.1) led to low HV contamination without compromising HDV yields. Indeed, such MOI ratio was sufficient to reduce HV levels, as these were similar either in MDCK-E1 or MDCK-E1-Cre cells. This raises the possibility of producing HDVs without Cre-expressing cells, which would circumvent the negative effects that this recombinase holds to the production system. Here, we show how Cre and MOI ratio impact adenovirus vectors yields and infectivity, providing key-information to design an improved manufacturing of HDV. Potential mechanisms to explain how Cre is specifically impacting cell productivity without critically compromising its growth are presented.