Finite-temperature relativistic Landau problem and the relativistic quantum Hall effect

This paper presents a study of the free energy and particle density of the relativistic Landau problem, and their relevance to the quantum Hall effect. We study first the zero temperature Casimir energy and fermion number for Dirac fields in a 2+1-dimensional Minkowski space-time, in the presence of a uniform magnetic field perpendicular to the spatial manifold. Then, we go to the finite-temperature problem, with a chemical potential, introduced as a uniform zero component of the gauge potential. By performing a Lorentz boost, we obtain Hall's conductivity in the case of crossed electric and magnetic fields.Comment: Final version, to appear in Journal of Physics A: Mathematical and Genera

De novo RANBP2 variant in a fetal demise case with cerebral intraparenchymal hemorrhage.

Fetal intracranial hemorrhage (ICH) may result from a wide array of causes, either associated with maternal or fetal risk factors. In the last decade, monogenic causes of susceptibility to fetal ICH have been described, in particular in association with COL4A1 and COL4A2 genes. A peculiar form of ICH is acute necrotizing encephalitis (ANE), which is characterized by a rapid-onset severe encephalopathy following an abnormal inflammatory response to an otherwise banal infection. It usually affects healthy children and it is thought to be multifactorial, with a genetic predisposition. RANBP2 gene has been extensively associated with ANE susceptibility. We hereby present a unique case of a 42-year-old secundigravida with intrauterine fetal demise at 35 weeks of gestation. Trio-based whole-exome sequencing performed on both parents and fetal DNA showed a de novo likely pathogenic variant in the RANBP2 gene on 2q13. At the fetal autopsy, subtentorial hematoma and cerebral intraparenchymal hemorrhage were present. We speculate that this might be a new phenotypic presentation of RANBP2-associated disease. However, more similar fetal cases need to be reported in order to reinforce this hypothesis

Identifying high-confidence variants in human cytomegalovirus genomes sequenced from clinical samples

Understanding the intrahost evolution of viral populations has implications in pathogenesis, diagnosis and treatment, and has recently made impressive advances from developments in high-throughput sequencing. However, the underlying analyses are very sensitive to sources of bias, error and artefact in the data, and it is important that these are addressed adequately if robust conclusions are to be drawn. The key factors include: (i) determining the number of viral strains present in the sample analysed; (ii) monitoring the extent to which the data represent these strains and assessing the quality of these data; (iii) dealing with the effects of cross-contamination; and (iv) ensuring that the results are reproducible. We investigated these factors by generating sequence datasets, including biological and technical replicates, directly from clinical samples obtained from a small cohort of patients who had been infected congenitally with the herpesvirus human cytomegalovirus, with the aim of developing a strategy for identifying high-confidence intrahost variants. We found that such variants were few in number and typically present in low proportions, and concluded that human cytomegalovirus exhibits a very low level of intrahost variability. In addition to clarifying the situation regarding human cytomegalovirus, our strategy has wider applicability to understanding the intrahost variability of other viruses

Prevalence, Outcome, and Prevention of Congenital Cytomegalovirus Infection in Neonates Born to Women With Preconception Immunity (CHILd Study)

Background. Human cytomegalovirus (HCMV) is the leading infectious cause of congenital disabilities. We designed a prospective study to investigate the rate, outcome, and risk factors of congenital CMV (cCMV) infection in neonates born to immune women, and the potential need and effectiveness of hygiene recommendations in this population.Methods. The study was composed of 2 sequential parts: an epidemiology (part 1) and a prevention (part 2) study. Performance of part 2 depended upon a cCMV rate >0.4%. Women enrolled in part 1 did not receive hygiene recommendations. Newborns were screened by HCMV DNA testing in saliva and cCMV was confirmed by urine testing.Results. Saliva swabs were positive for HCMV DNA in 45/9661 newborns and cCMV was confirmed in 18 cases. The rate of cCMV was .19% (95% confidence interval [CI]: .11-.29%), and 3 out of 18 infants with cCMV had symptoms of CMV at birth. Age, nationality, occupation, and contact with children were similar between mothers of infected and noninfected newborns. Twin pregnancy (odds ratio [OR]: 7.2; 95% CI: 1.7-32.2; P=.037) and maternal medical conditions (OR: 3.9; 95% CI: 1.5-10.1; P= .003) appeared associated with cCMV. Given the rate of cCMV was lower than expected, the prevention part of the study was cancelled.Conclusions. Newborns from women with preconception immunity have a low rate of cCMV, which appears to be mostly due to reactivation of the latent virus. Therefore, serological screening in childbearing age would be pivotal to identify HCMV-seropositive women, whose newborns have a low risk of cCMV

Human cytomegalovirus genomes sequenced directly from clinical material: variation, multiple-strain infection, recombination and gene loss

The genomic characteristics of human cytomegalovirus (HCMV) strains sequenced directly from clinical pathology samples were investigated, focusing on variation, multiple-strain infection, recombination, and gene loss. A total of 207 datasets generated in this and previous studies using target enrichment and high-throughput sequencing were analyzed, in the process enabling the determination of genome sequences for 91 strains. Key findings were that (i) it is important to monitor the quality of sequencing libraries in investigating variation; (ii) many recombinant strains have been transmitted during HCMV evolution, and some have apparently survived for thousands of years without further recombination; (iii) mutants with nonfunctional genes (pseudogenes) have been circulating and recombining for long periods and can cause congenital infection and resulting clinical sequelae; and (iv) intrahost variation in single-strain infections is much less than that in multiple-strain infections. Future population-based studies are likely to continue illuminating the evolution, epidemiology, and pathogenesis of HCMV

Prevalence, Outcome, and Prevention of Congenital Cytomegalovirus Infection in Neonates Born to Women with Preconception Immunity (CHILd Study)

Background: Human cytomegalovirus (HCMV) is the leading infectious cause of congenital disabilities. We designed a prospective study to investigate the rate, outcome, and risk factors of congenital CMV (cCMV) infection in neonates born to immune women, and the potential need and effectiveness of hygiene recommendations in this population. Methods: The study was composed of 2 sequential parts: an epidemiology (part 1) and a prevention (part 2) study. Performance of part 2 depended upon a cCMV rate >0.4%. Women enrolled in part 1 did not receive hygiene recommendations. Newborns were screened by HCMV DNA testing in saliva and cCMV was confirmed by urine testing. Results: Saliva swabs were positive for HCMV DNA in 45/9661 newborns and cCMV was confirmed in 18 cases. The rate of cCMV was. 19% (95% confidence interval [CI]:. 11-.29%), and 3 out of 18 infants with cCMV had symptoms of CMV at birth. Age, nationality, occupation, and contact with children were similar between mothers of infected and noninfected newborns. Twin pregnancy (odds ratio [OR]: 7.2; 95% CI: 1.7-32.2; P =. 037) and maternal medical conditions (OR: 3.9; 95% CI: 1.5-10.1; P =. 003) appeared associated with cCMV. Given the rate of cCMV was lower than expected, the prevention part of the study was cancelled. Conclusions: Newborns from women with preconception immunity have a low rate of cCMV, which appears to be mostly due to reactivation of the latent virus. Therefore, serological screening in childbearing age would be pivotal to identify HCMV-seropositive women, whose newborns have a low risk of cCMV. Clinical trials registration: www.clinicaltrials.gov (NCT03973359)

Stability of Yellow Fever Virus under Recombinatory Pressure as Compared with Chikungunya Virus

Recombination is a mechanism whereby positive sense single stranded RNA viruses exchange segments of genetic information. Recent phylogenetic analyses of naturally occurring recombinant flaviviruses have raised concerns regarding the potential for the emergence of virulent recombinants either post-vaccination or following co-infection with two distinct wild-type viruses. To characterize the conditions and sequences that favor RNA arthropod-borne virus recombination we constructed yellow fever virus (YFV) 17D recombinant crosses containing complementary deletions in the envelope protein coding sequence. These constructs were designed to strongly favor recombination, and the detection conditions were optimized to achieve high sensitivity recovery of putative recombinants. Full length recombinant YFV 17D virus was never detected under any of the experimental conditions examined, despite achieving estimated YFV replicon co-infection levels of ∼2.4×106 in BHK-21 (vertebrate) cells and ∼1.05×105 in C710 (arthropod) cells. Additionally YFV 17D superinfection resistance was observed in vertebrate and arthropod cells harboring a primary infection with wild-type YFV Asibi strain. Furthermore recombination potential was also evaluated using similarly designed chikungunya virus (CHIKV) replicons towards validation of this strategy for recombination detection. Non-homologus recombination was observed for CHIKV within the structural gene coding sequence resulting in an in-frame duplication of capsid and E3 gene. Based on these data, it is concluded that even in the unlikely event of a high level acute co-infection of two distinct YFV genomes in an arthropod or vertebrate host, the generation of viable flavivirus recombinants is extremely unlikely