Alzheimer's disease-associated CD83(+) microglia are linked with increased immunoglobulin G4 and human cytomegalovirus in the gut, vagal nerve, and brain.

Introduction: While there may be microbial contributions to Alzheimer's disease (AD), findings have been inconclusive. We recently reported an AD-associated CD83(+) microglia subtype associated with increased immunoglobulin G4 (IgG4) in the transverse colon (TC).

Methods: We used immunohistochemistry (IHC), IgG4 repertoire profiling, and brain organoid experiments to explore this association.

Protective effect of pre-existing natural immunity in a nonhuman primate reinfection model of congenital cytomegalovirus infection.

Congenital cytomegalovirus (cCMV) is the leading infectious cause of neurologic defects in newborns with particularly severe sequelae in the setting of primary CMV infection in the first trimester of pregnancy. The majority of cCMV cases worldwide occur after non-primary infection in CMV-seropositive women; yet the extent to which pre-existing natural CMV-specific immunity protects against CMV reinfection or reactivation during pregnancy remains ill-defined. We previously reported on a novel nonhuman primate model of cCMV in rhesus macaques where 100% placental transmission and 83% fetal loss were seen in CD4+ T lymphocyte-depleted rhesus CMV (RhCMV)-seronegative dams after primary RhCMV infection.

The pentameric complex is not required for vertical transmission of cytomegalovirus in seronegative pregnant rhesus macaques.

Unlabelled: Congenital cytomegalovirus (cCMV) infection is the leading infectious cause of neonatal neurological impairment but essential virological determinants of transplacental CMV transmission remain unclear. The pentameric complex (PC), composed of five subunits, glycoproteins H (gH), gL, UL128, UL130, and UL131A, is essential for efficient entry into non-fibroblast cells . Based on this role in cell tropism, the PC is considered a possible target for CMV vaccines and immunotherapies to prevent cCMV.

Protective effect of pre-existing natural immunity in a nonhuman primate reinfection model of congenital cytomegalovirus infection.

Unlabelled: Congenital cytomegalovirus (cCMV) is the leading infectious cause of neurologic defects in newborns with particularly severe sequelae in the setting of primary CMV infection in the first trimester of pregnancy. The majority of cCMV cases worldwide occur after non-primary infection in CMV-seropositive women; yet the extent to which pre-existing natural CMV-specific immunity protects against CMV reinfection or reactivation during pregnancy remains ill-defined. We previously reported on a novel nonhuman primate model of cCMV in rhesus macaques where 100% placental transmission and 83% fetal loss were seen in CD4 T lymphocyte-depleted rhesus CMV (RhCMV)-seronegative dams after primary RhCMV infection.

Identification of a Permissive Secondary Mutation That Restores the Enzymatic Activity of Oseltamivir Resistance Mutation H275Y.

Many oseltamivir resistance mutations exhibit fitness defects in the absence of drug pressure that hinders their propagation in hosts. Secondary permissive mutations can rescue fitness defects and facilitate the segregation of resistance mutations in viral populations. Previous studies have identified a panel of permissive or compensatory mutations in neuraminidase (NA) that restore the growth defect of the predominant oseltamivir resistance mutation (H275Y) in H1N1 influenza A virus.

Common Polymorphisms in the Glycoproteins of Human Cytomegalovirus and Associated Strain-Specific Immunity.

Human cytomegalovirus (HCMV), one of the most prevalent viruses across the globe, is a common cause of morbidity and mortality for immunocompromised individuals. Recent clinical observations have demonstrated that mixed strain infections are common and may lead to more severe disease progression. This clinical observation illustrates the complexity of the HCMV genome and emphasizes the importance of taking a population-level view of genotypic evolution.

A Generally Applicable CRISPR/Cas9 Screening Technique to Identify Host Genes Required for Virus Infection as Applied to Human Cytomegalovirus (HCMV) Infection of Epithelial Cells.

Clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 screens enable virus-host genetic screens to be undertaken in a more robust manner than previously possible and has had a tremendous impact in the field of virus study. Researchers can take advantage of the power of CRISPR genetic screens to discover virus-host interaction genes including host receptors and signaling molecules (Bazzone et al., mBio 10 (1): e02734-18, 2019; E et al.

In vitro and in vivo characterization of a recombinant rhesus cytomegalovirus containing a complete genome.

Cytomegaloviruses (CMVs) are highly adapted to their host species resulting in strict species specificity. Hence, in vivo examination of all aspects of CMV biology employs animal models using host-specific CMVs. Infection of rhesus macaques (RM) with rhesus CMV (RhCMV) has been established as a representative model for infection of humans with HCMV due to the close evolutionary relationships of both host and virus.

Imposed mutational meltdown as an antiviral strategy.

Following widespread infections of the most recent coronavirus known to infect humans, SARS-CoV-2, attention has turned to potential therapeutic options. With no drug or vaccine yet approved, one focal point of research is to evaluate the potential value of repurposing existing antiviral treatments, with the logical strategy being to identify at least a short-term intervention to prevent within-patient progression, while long-term vaccine strategies unfold. Here, we offer an evolutionary/population-genetic perspective on one approach that may overwhelm the capacity for pathogen defense (i.

OR14I1 is a receptor for the human cytomegalovirus pentameric complex and defines viral epithelial cell tropism.

A human cytomegalovirus (HCMV) pentameric glycoprotein complex (PC), gH-gL-UL128-UL130-UL131A, is necessary for viral infection of clinically relevant cell types, including epithelial cells, which are important for interhost transmission and disease. We performed genome-wide CRISPR/Cas9 screens of different cell types in parallel to identify host genes specifically required for HCMV infection of epithelial cells. This effort identified a multipass membrane protein, OR14I1, as a receptor for HCMV infection.

Viral Infection or IFN-α Alters Mitotic Spindle Orientation by Modulating Pericentrin Levels.

Congenital microcephaly occurs in utero during Zika virus (ZIKV) infection. The single-gene disorder, Majewski osteodysplastic primordial dwarfism type II (MOPDII), also leads to microcephaly and is concomitant with a decrease in the centrosomal protein, pericentrin (PCNT). This protein is a known contributor of mitotic spindle misorientation and ultimately, microcephaly.

Gene Silencing With siRNA (RNA Interference): A New Therapeutic Option During Ex Vivo Machine Liver Perfusion Preservation.

RNA interference (RNAi) is a natural process of posttranscriptional gene regulation that has raised a lot of attention culminating with the Nobel Prize in Medicine in 2006. RNAi-based therapeutics have been tested in experimental transplantation to reduce ischemia/reperfusion injury (IRI) with success. Modulation of genes of the innate immune system, as well as apoptotic genes, and those involved in the nuclear factor kappa B pathways can reduce liver injury in rodent liver pedicle clamping and transplantation models of IRI.

A Comparative Study of Single and Dual Perfusion During End-ischemic Subnormothermic Liver Machine Preservation.

Background: It remains controversial if arterial perfusion in addition to portal vein perfusion during machine preservation improves liver graft quality. Comparative studies using both techniques are lacking. We studied the impact of using single or dual machine perfusion of donation after circulatory death rat livers.

Mutations in Influenza A Virus Neuraminidase and Hemagglutinin Confer Resistance against a Broadly Neutralizing Hemagglutinin Stem Antibody.

Influenza A virus (IAV), a major cause of human morbidity and mortality, continuously evolves in response to selective pressures. Stem-directed, broadly neutralizing antibodies (sBnAbs) targeting the influenza virus hemagglutinin (HA) are a promising therapeutic strategy, but neutralization escape mutants can develop. We used an integrated approach combining viral passaging, deep sequencing, and protein structural analyses to define escape mutations and mechanisms of neutralization escape for the F10 sBnAb.

Synonymous Mutations at the Beginning of the Influenza A Virus Hemagglutinin Gene Impact Experimental Fitness.

The fitness effects of synonymous mutations can provide insights into biological and evolutionary mechanisms. We analyzed the experimental fitness effects of all single-nucleotide mutations, including synonymous substitutions, at the beginning of the influenza A virus hemagglutinin (HA) gene. Many synonymous substitutions were deleterious both in bulk competition and for individually isolated clones.

On the Demographic and Selective Forces Shaping Patterns of Human Cytomegalovirus Variation within Hosts.

Human cytomegalovirus (HCMV) is a member of the β -herpesvirus subfamily within Herpesviridae that is nearly ubiquitous in human populations, and infection generally results only in mild symptoms. However, symptoms can be severe in immunonaive individuals, and transplacental congenital infection of HCMV can result in serious neurological sequelae. Recent work has revealed much about the demographic and selective forces shaping the evolution of congenitally transmitted HCMV both on the level of hosts and within host compartments, providing insight into the dynamics of congenital infection, reinfection, and evolution of HCMV with important implications for the development of effective treatments and vaccines.

Structural Determination of the Broadly Reactive Anti-IGHV1-69 Anti-idiotypic Antibody G6 and Its Idiotope.

The heavy chain IGHV1-69 germline gene exhibits a high level of polymorphism and shows biased use in protective antibody (Ab) responses to infections and vaccines. It is also highly expressed in several B cell malignancies and autoimmune diseases. G6 is an anti-idiotypic monoclonal Ab that selectively binds to IGHV1-69 heavy chain germline gene 51p1 alleles that have been implicated in these Ab responses and disease processes.

The Combined Effect of Oseltamivir and Favipiravir on Influenza A Virus Evolution.

Influenza virus inflicts a heavy death toll annually and resistance to existing antiviral drugs has generated interest in the development of agents with novel mechanisms of action. Favipiravir is an antiviral drug that acts by increasing the genome-wide mutation rate of influenza A virus (IAV). Potential synergistic benefits of combining oseltamivir and favipiravir have been demonstrated in animal models of influenza, but the population-level effects of combining the drugs are unknown.

Antiviral drug resistance as an adaptive process.

Antiviral drug resistance is a matter of great clinical importance that, historically, has been investigated mostly from a virological perspective. Although the proximate mechanisms of resistance can be readily uncovered using these methods, larger evolutionary trends often remain elusive. Recent interest by population geneticists in studies of antiviral resistance has spurred new metrics for evaluating mutation and recombination rates, demographic histories of transmission and compartmentalization, and selective forces incurred during viral adaptation to antiviral drug treatment.

Characterizing human cytomegalovirus reinfection in congenitally infected infants: an evolutionary perspective.

Given the strong selective pressures often faced by populations when colonizing a novel habitat, the level of variation present on which selection may act is an important indicator of adaptive potential. While often discussed in an ecological context, this notion is also highly relevant in our clinical understanding of viral infection, in which the novel habitat is a new host. Thus, quantifying the factors determining levels of variation is of considerable importance for the design of improved treatment strategies.

On the Analysis of Intrahost and Interhost Viral Populations: Human Cytomegalovirus as a Case Study of Pitfalls and Expectations.

Intrahost and interhost assessments of viral diversity are often treated as measures of separate and distinct evolutionary processes, with numerous investigations reporting seemingly incompatible results between the two. For example, in human cytomegalovirus, the nucleotide diversity estimates are 10-fold higher for interhost data, while the number of segregating (i.e.

Molecular Basis for Differential Patterns of Drug Resistance in Influenza N1 and N2 Neuraminidase.

Neuraminidase (NA) inhibitors are used for the prevention and treatment of influenza A virus infections. Two subtypes of NA, N1 and N2, predominate in viruses that infect humans, but differential patterns of drug resistance have emerged in each subtype despite highly homologous active sites. To understand the molecular basis for the selection of these drug resistance mutations, structural and dynamic analyses on complexes of N1 and N2 NA with substrates and inhibitors were performed.

An experimental evaluation of drug-induced mutational meltdown as an antiviral treatment strategy.

The rapid evolution of drug resistance remains a critical public health concern. The treatment of influenza A virus (IAV) has proven particularly challenging, due to the ability of the virus to develop resistance against current antivirals and vaccines. Here, we evaluate a novel antiviral drug therapy, favipiravir, for which the mechanism of action in IAV involves an interaction with the viral RNA-dependent RNA polymerase resulting in an effective increase in the viral mutation rate.

Identification of Zika Virus and Dengue Virus Dependency Factors using Functional Genomics.

The flaviviruses dengue virus (DENV) and Zika virus (ZIKV) are severe health threats with rapidly expanding ranges. To identify the host cell dependencies of DENV and ZIKV, we completed orthologous functional genomic screens using RNAi and CRISPR/Cas9 approaches. The screens recovered the ZIKV entry factor AXL as well as multiple host factors involved in endocytosis (RAB5C and RABGEF), heparin sulfation (NDST1 and EXT1), and transmembrane protein processing and maturation, including the endoplasmic reticulum membrane complex (EMC).