Determining the subcellular localization of the L1 ORF2 protein (ORF2p) has been impossible to date because of technical limitations in detecting either endogenous or overexpressed forms of the protein. Here we report visualization of the full-length ORF2p in cultured human cells following expression in a modified vaccinia virus/T7 RNA polymerase (MVA/T7RP) system. The MVA/T7RP system was used to ascertain subcellular localization of L1 ORF1p and ORF2p both as fusions with green fluorescent protein and by immunocytochemistry. Full-length ORF2p was predominantly cytoplasmic, while carboxy-terminal-deleted ORF2p localized additionally to the nucleolus. We mapped a functional nucleolar localization signal in ORF2p. ORF1p appeared in the cytoplasm with a speckled pattern and colocalized with ORF2p in nucleoli in a subset of cells. These findings help explain the presence of chimeras between L1s and small RNA gene sequences recently discovered in the human genome.

Testing of paired mid-turbinate (MT) nasal and nasopharyngeal (NP) swabs, collected by trained personnel from 40 patients with COVID-19 showed more NP (76/95, 80%) than MT swabs tested positive (61/95, 64%; p=0.02). Among samples collected a week after study enrollment, fewer MT than NP samples were positive (45% vs 76%; p=0.001).

Congenital human cytomegalovirus (HCMV) infection is a significant cause of abnormal neurodevelopment and long-term neurological sequelae in infants and children. Resident cell populations of the developing brain have been suggested to be more susceptible to virus-induced cytopathology, a pathway thought to contribute to the clinical outcomes following intrauterine HCMV infection. However, recent findings in a newborn mouse model of the infection in the developing brain have indicated that elevated levels of proinflammatory mediators leading to mononuclear cell activation and recruitment could underlie the abnormal neurodevelopment. In this study, we demonstrate that treatment with tumor necrosis factor alpha (TNF-␣)-neutralizing antibodies decreased the frequency of CD45 ϩ Ly6C hi CD11b ϩ CCR2 ϩ activated myeloid mononuclear cells (MMCs) and the levels of proinflammatory cytokines in the blood and the brains of murine CMVinfected mice. This treatment also normalized neurodevelopment in infected mice without significantly impacting the level of virus replication. These results indicate that TNF-␣ is a major component of the inflammatory response associated with altered neurodevelopment that follows murine CMV infection of the developing brain and that a subset of peripheral blood myeloid mononuclear cells represent a key effector cell population in this model of virus-induced inflammatory disease of the developing brain.IMPORTANCE Congenital human cytomegalovirus (HCMV) infection is the most common viral infection of the developing human fetus and can result in neurodevelopmental sequelae. Mechanisms of disease leading to neurodevelopmental deficits in infected infants remain undefined, but postulated pathways include loss of neuronal progenitor cells, damage to the developing vascular system of the brain, and altered cellular positioning. Direct virus-mediated cytopathic effects cannot explain the phenotypes of brain damage in most infected infants. Using a mouse model that recapitulates characteristics of the brain infection described in human infants, we have shown that TNF-␣ plays a key role in brain inflammation, including recruitment of inflammatory mononuclear cells. Neutralization of TNF-␣ normalized neurodevelopmental abnormalities in infected mice, providing evidence that virus-induced inflammation is a major component of disease in the developing brain. These results suggest that interventions limiting inflammation associated with the infection could potentially improve the neurologic outcome of infants infected in utero with HCMV.

The frequency distribution of the retrotransposon Osvaldo in the haploid genome of Drosophila buzzatii has been studied in five natural populations from the Iberian Peninsula and six natural populations from Argentina. In Iberian populations, Osvaldo insertion sites do not follow a Poisson distribution, most probably due to eight euchromatic sites with high occupancy, found in all populations. The estimated alpha and beta parameters, which measure the relative importance of drift and negative selection in shaping frequency distributions, indicate that drift is the main force acting upon the distribution of Osvaldo in natural populations of D. buzzatii in the Iberian Peninsula. On the other hand, Osvaldo distribution in populations from Argentina is similar to the distribution of elements with low copy numbers, such as those described for Drosophila melanogaster and Drosophila simulans: there are no indications for deviation from a Poisson distribution, there is a low occupancy per insertion site, and genetic drift has no apparent effect on the frequency distribution. We propose that the unusual distribution found in the populations from the Iberian Peninsula is a consequence of the colonization process. Iberian Peninsula populations suffered a genomic redistribution of Osvaldo, most probably after a founder effect. Consequently, certain copies that arrived at high frequencies are showing a high occupancies today, and the mean copy number of Osvaldo is higher in Iberian Peninsula populations than in populations from Argentina. All other copies are the result of recent (after colonization) transposition events.

In Type 1 diabetes (T1D), reactive oxygen species (ROS) and pro-inflammatory cytokines produced by macrophages and other innate immune cells destroy pancreatic β-cells while promoting autoreactive T cell maturation. Superoxide-deficient Non-Obese Diabetic mice (NOD.Ncf1m1J) are resistant to spontaneous diabetes, revealing the integral role of ROS-signaling in T1D. Here, we evaluate the innate immune activation state of bone marrow-derived macrophages (BM-Mϕ) from NOD and NOD.Ncf1m1J mice after poly(I:C)-induced Toll-like receptor 3 (TLR3) signaling. We show that ROS synthesis is required for efficient activation of the NF-κB signaling pathway and concomitant expression of TLR3 and the cognate adaptor molecule, TRIF. Poly(I:C)-stimulated NOD.Ncf1m1J BM-Mϕ exhibited a 2- and 10-fold decrease in TNF-α and IFN-β pro-inflammatory cytokine synthesis, respectively, in contrast to NOD BM-Mϕ. Optimal expression of IFN-α/β is not solely dependent on superoxide synthesis, but requires p47phox to function in a NOX-independent manner to mediate Type I interferon synthesis. Interestingly, MHC-II I-Ag7 expression necessary for CD4 T cell activation is increased 2-fold relative to NOD, implicating a role for superoxide in I-Ag7 down-regulation. These findings suggest that defective innate immune pattern-recognition receptor activation and subsequent decrease in TNF-α and IFN-β pro-inflammatory cytokine synthesis necessary for autoreactive T cell maturation, may contribute to the T1D protection observed in NOD.Ncf1m1J mice.

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BACKGROUND Human cytomegalovirus (CMV) infection is associated with inferior survival in renal transplant patients, and ganciclovir (GCV) prophylaxis is associated with improved survival. In a murine CMV (MCMV) renal transplant model, GCV prophylaxis improved innate infiltrates and allograft damage during the period of prophylaxis. In this study, late effects were examined after discontinuation of prophylaxis. METHODS MCMV D+/R− and D−/R− allogeneic transplants were performed with cyclosporine immunosuppression. One D+/R− cohort received GCV prophylaxis for 14 days post-transplant, followed by 28 days without GCV. At 42 days post-transplant, grafts were analyzed for histologic tissue damage and immune infiltrates. Another D+/R− cohort was treated with anti-NK1.1 antibodies for 14 days post-transplant and compared to animals without NK depletion. RESULTS At day 42, MCMV infected transplants had higher damage scores (15.6+/−0.6) compared to uninfected transplants (8.3+/−0.9) (p<0.01), which improved in GCV treated allografts (9.5+/−1.4). MCMV infected grafts contained greater frequencies of natural killer (NK) cell and myeloid infiltrates compared to uninfected grafts (p<0.05), which decreased in the GCV treated grafts. NK depletion improved allograft histology of MCMV infected grafts. CONCLUSIONS MCMV infection exacerbates late renal allograft damage and is associated with NK and myeloid cell infiltrates. GCV prophylaxis reduces allograft injury, NK cell and myeloid infiltrates even after cessation of prophylaxis. NK depletion in MCMV infected transplants also improves histology. These results suggest that GCV prophylaxis may have a long-term beneficial effect upon CMV infected renal allografts, and suggest a potential role for NK cells in the pathogenesis of CMV associated allograft injury.

Table of Contents Summary:SARS-CoV-2 viral load in the respiratory tract is significantly higher in children < 1 year and in those with symptomatic disease.What is known on this subject: Data on clinical characteristics of children with SARS-CoV-2 is widely available compared to limited information on virological characteristics, particularly in children with asymptomatic and mild infections. What this study adds:Children with COVID-19 are predominantly asymptomatic or have mild illness despite high viral load (VL) levels in the respiratory tract and at other sites, irrespective of age, severity of illness and underlying co-morbidities.