The transcriptional underpinnings of brain development remain poorly understood, particularly in humans and closely related non-human primates. We describe a high resolution transcriptional atlas of rhesus monkey brain development that combines dense temporal sampling of prenatal and postnatal periods with fine anatomical parcellation of cortical and subcortical regions associated with human neuropsychiatric disease. Gene expression changes more rapidly before birth, both in progenitor cells and maturing neurons, and cortical layers and areas acquire adult-like molecular profiles surprisingly late postnatally. Disparate cell populations exhibit distinct developmental timing but also unexpected synchrony of processes underlying neural circuit construction including cell projection and adhesion. Candidate risk genes for neurodevelopmental disorders including primary microcephaly, autism spectrum disorder, intellectual disability, and schizophrenia show disease-specific spatiotemporal enrichment within developing neocortex. Human developmental expression trajectories are more similar to monkey than rodent, and approximately 9% of genes show human-specific regulation with evidence for prolonged maturation or neoteny.

A role for interferon (IFN) in modulating infection

Although prior studies have investigated cellular infection by dengue virus (DV), many have used highly passaged strains. We have reassessed cellular infection by DV type 2 (DV2) using prototype and low-passage isolates representing genotypes from different geographic areas. We observed marked variation in the susceptibility to infection among cell types by different DV2 strains. HepG2 hepatoma cells were susceptible to infection by all DV2 strains assayed. Although the prototype strain generated higher titers of secreted virus than the low-passage isolates, this difference did not correspond to positive-or negative-strand viral RNA levels and thus may reflect variation in efficiency among DV2 isolates to translate viral proteins or package and/or secrete virus. In contrast, human foreskin fibroblasts were susceptible to the prototype and low-passage Thai isolates but not to five Nicaraguan strains tested, as reflected by the absence of accumulation of negative-strand viral RNA, viral antigen, and infectious virus. A similar pattern was observed with the antibody-dependent pathway of infection. U937 and THP-1 myeloid cells and peripheral blood monocytes were infected in the presence of enhancing antibodies by the prototype strain but not by low-passage Nicaraguan isolates. Again, the barrier appeared to be prior to negative-strand accumulation. Thus, depending on the cell type and viral isolate, blocks that limit the production of infectious virus in vitro may occur at distinct steps in the pathway of cellular infection.Dengue virus (DV) is a single-stranded positive-polarity enveloped RNA flavivirus that causes dengue fever (DF), the most prevalent arthropod-borne viral illness in humans. Four DV serotypes are transmitted by mosquitoes, and infection results in a clinical spectrum ranging from an acute, self-limited febrile illness (DF) to a life-threatening syndrome (dengue hemorrhagic fever/dengue shock syndrome [DHF/DSS]). Globally, DV causes an estimated 100 million new cases of DF and 250,000 cases of DHF/DSS per year, with 2.5 billion people at risk (40). Despite the worldwide morbidity associated with DV infection, neither the molecular virology nor the pathogenesis of DV is well characterized.In primary DV infection, DV enters target cells after the envelope protein E attaches to an uncharacterized receptor that may display highly sulfated glycosaminoglycans (7). Secondary infection occurs after inoculation with a different DV serotype. In this case, the virus enters cells through a primary receptor but also may form immune complexes with preexisting nonneutralizing antibodies and interact with alternate receptors (9) such as Fc␥ receptors I and II (32), resulting in antibody-dependent enhancement of infection (ADE) (14, 16). ADE is hypothesized to contribute to the pathogenesis of severe dengue illness (16, 23), as epidemiological studies have identified secondary infection as a risk factor for DHF and have shown that the presence of preexisting anti-DV antibodies correlates with DHF (6, 54). Nonethele...

In recent years, dengue viruses (serotypes 1 to 4) have spread throughout tropical regions worldwide. In many places, multiple dengue virus serotypes are circulating concurrently, which may increase the risk for the more severe form of the disease, dengue hemorrhagic fever. For the control and prevention of dengue fever, it is important to rapidly detect and type the virus in clinical samples and mosquitoes. Assays based on reverse transcriptase (RT) PCR (RT-PCR) amplification of dengue viral RNA can offer a rapid, sensitive, and specific approach to the typing of dengue viruses. We have reduced a two-step nested RT-PCR protocol to a single-tube reaction with sensitivity equivalent to that of the two-step protocol (1 to 50 PFU) in order to maximize simplicity and minimize the risk of sample cross-contamination. This assay was also optimized for use with a thermostable RT-polymerase. We designed a plasmid-based internal control that produces a uniquely sized product and can be used to control for both reverse transcription or amplification steps without the risk of generating false-positive results. This single-tube RT-PCR procedure was used to type dengue viruses during the 1995 and 1997-1998 outbreaks in Nicaragua. In addition, an extraction procedure that permits the sensitive detection of viral RNA in pools of up to 50 mosquitoes without PCR inhibition or RNA degradation was developed. This assay should serve as a practical tool for use in countries where dengue fever is endemic, in conjunction with classical methods for surveillance and epidemiology of dengue viruses.