Biology subjects

de Souza, M.

Publications and source records attributed to de Souza, M..

4 recordsLinked to original sources

bioRxiv2026

Powassan Virus LB Neurovirulence and Lethality is Determined by Envelope Protein Domain III Residues

Powassan Viruses (POWV) are tick-borne Flaviviruses that cause lethal encephalitis and long-term neurologic sequelae. POWVs are divided into two lineages that share 86% genetic identity. POWV-LB (Lin I) was isolated from a fatal case of encephalitis, while POWV-LI9 (Lin II) is a tick-derived isolate that causes age-dependent lethality in mice. Domain III of Flavivirus envelope proteins (EDIII) directs cell attachment, and determines murine neuropathology and lethality. Here we developed POWV LB reverse genetics, analyzed the CNS of LB and recLB mutant infected mice, and assessed the role of EDIII residues in LB pathogenesis. LB infection of 50-week-old B6 mice focally activated microglia in the midbrain and cerebellum discrete from, and independent of, the location of envelope protein in the cerebral cortex, hippocampus and thalamus. Reverse genetic analysis of LB EDIII residues revealed that mutating D308N only partially reduced LB neuropathology and lethality. However, mutating D308N along with an adjacent EDIII residue, A310T, completely abolished LB-D308N/A310T neurovirulence, neuroinvasion and lethality, yet elicited neutralizing antibody responses that protected mice from a lethal WT LB challenge. Signifying changes in neurotropism, LB-D308N/A310T failed to activate microglia or yield detectable POWV RNA and antigen in the CNS. Overall, recombinant LB-D308N/A310T mutants fail to induce neurologic symptoms or neuropathology while eliciting a protective immune response. These findings reveal that EDIII residues determine the neurovirulence and lethality of lineage I POWVs and that genetically modifying EDIII provides a mechanism for POWV attenuation and vaccine development. ImportancePowassan virus causes lethal encephalitis and long-term neurological sequalae in survivors; however, there are currently no licensed POWV vaccines or therapeutics. POWVs are comprised of two genetic lineages (LB-Lin I; LI9 Lin II) that are derived from discrete ticks and small mammal hosts. Flavivirus envelope proteins determine cell attachment, viral tropism, and neurovirulent spread and lethality in mice. Here we created a POWV LB reverse genetics system and assessed mutations that determine LB neurovirulence in 50 wk old mice. Studies reveal novel LB neuropathology with divergent patterns of gliosis and POWV antigen expression within the CNS. Mice infected with an LB-D308N/A310T envelope mutant elicited responses that protect mice from a lethal LB challenge and failed to enter the CNS, cause neurologic symptoms, CNS pathology or lethality. LB reverse genetics permits defining determinants of LB neurovirulence that are required for rational vaccine development.

microbiology↗

bioRxiv2022

Productive and latent HIV infections originate in resting CD4+ T cells

Productively and latently HIV-infected cells are the source of virus that respectively establishes and sustains systemic infections and the reservoir in which HIV persists and rebounds when anti-retroviral therapy (ART) is interrupted. While infected activated CD4+ T cells are thought to be the principal source of HIV production, and reversion of activated infected cells to a resting state as the major pathway to establishment of the latently infected cell reservoir, we now show that in the earliest stages of detectable HIV infection in the lymphoid tissue reservoir, infection of resting CD4+ T cells establishes the first populations of both productively and latently infected cells. We further show that the early infection of resting T cells reflects their predominance in lymphoid tissues and the expression of pTEFb in vivo in resting T cells to support their infection. The immediate establishment of productively and latently infected cell populations enable HIV to propagate and persist, and generates reservoirs from which infection can rebound despite instituting ART at the earliest stage of detectable infection.

immunology↗

bioRxiv2019

Genetic regulators of mineral amount in Nelore cattle muscle predicted by a new co-expression and regulatory impact factor approach

Mineral amount in bovine muscle affect meat quality, growth, health and reproductive traits in beef cattle. To better understand the genetic basis of this phenotype, we implemented new applications of use for two complementary algorithms: the partial correlation and information theory (PCIT) and the regulatory impact factor (RIF), by including GEBVs as part of the input. We used PCIT to determine putative regulatory relationships based on significant associations between gene expression and mineral amount. Then, RIF was used to determine the regulatory impact of genes and miRNA expression over mineral amount. We also investigated over-represented pathways, as well as evidences from previous studies carried in the same population, to determine regulatory genes for mineral amount e.g. NOX1, whose expression was positively correlated to Zn and was described as regulated by this mineral in humans. With this methodology, we were able to identify genes, miRNAs and pathways not yet described as important for mineral amount. The results support the hypothesis that extracellular matrix interactions are the core regulator of mineral amount in muscle cells. Putative regulators described here add information to this hypothesis, expanding the molecular relationships between gene expression and minerals.

genomics↗

bioRxiv2018

Monocyte Infection Dynamics Shape HIV-1 Phyloanatomy in the Peripheral Blood

Human immunodeficiency virus (HIV) RNA and DNA have been isolated from patient monocytes, an immune cell population that is quite different in several aspects from the canonical T-cell viral target. Because monocytes are migratory and resilient to both natural and synthetic antiviral defenses, knowledge of the contribution of monocyte infection to ongoing viral evolution and spread in vivo is of significant interest for drug development and treatment strategies. Using single viral genome sequencing from different peripheral blood compartments and phyloanatomic statistical inference, we demonstrate that productively infected monocytes follow an evolutionary trajectory that is distinct from peripheral T cells during multiple stages of disease progression. Gene flow and selection analysis reveal plasticity in the source of monocyte infection and in the region of the HIV envelope glycoprotein that experiences selection pressure across individuals. The findings, thus, point to a potential reservoir showing a range of infection and transmission dynamics, for which the current universal, T cell-targeted treatment strategies would be inadequate.\n\nAuthor summaryHuman immunodeficiency virus is a rapidly evolving virus, allowing its genetic material to act as a fingerprint for epidemiological processes among, as well as within, individual infected hosts. In this study, sampling of viral RNA from plasma and differing infected immune cell populations from the peripheral blood was undertaken for three separate individuals in order to infer such processes. The results revealed a productively infected monocyte cell population, for which distinct selection pressures were linked to differing spatiotemporal origins of infection. In light of previous evidence of the migratory nature of these cells and resilience to both natural and synthetic antiviral defenses, this study underscores the importance of further investigation into the role of monocytes, and monocyte-rich tissues, as viral reservoirs during treatment of HIV with antiretroviral therapy.

evolutionary biology↗