Biology subjects

Weiler, A. M.

Publications and source records attributed to Weiler, A. M..

26 records · Page 2Linked to original sources

bioRxiv2019

Pharyngeal motor cortex grey matter abnormalities and retinal photoreceptor layer dysfunction in macaques exposed to Zika virus in utero

Congenital Zika virus (ZIKV) exposure results in a spectrum of disease ranging from severe birth defects to delayed onset neurodevelopmental deficits. ZIKV-related neuropathogenesis, predictors of birth defects, and neurodevelopmental deficits are not well defined in people. Here we assess the methodological and statistical feasibility of a congenital ZIKV exposure macaque model for identifying infant neurobehavior and brain abnormalities that may underlie neurodevelopmental deficits. We inoculated five pregnant macaques with ZIKV and mock-inoculated one macaque in the first trimester. Following birth, growth, ocular structure/function, brain structure, hearing, histopathology, and neurobehavior were quantitatively assessed during the first week of life. We identified the typical pregnancy outcomes of congenital ZIKV infection, with fetal demise and placental abnormalities. We estimated sample sizes needed to define differences between groups and demonstrated that future studies quantifying brain region volumes, retinal structure, hearing, and visual pathway function require a sample size of 14 animals per group (14 ZIKV, 14 control) to detect statistically significant differences in at least half of the infant exam parameters. Establishing the parameters for future studies of neurodevelopmental outcomes following congenital ZIKV exposure in macaques is essential for robust and rigorous experimental design.

microbiology↗

bioRxiv2019

Long-term protection of rhesus macaques from Zika virus reinfection

By the end of the 2016 Zika virus (ZIKV) outbreak, it is estimated that there were up to 100 million infections in the Americas. In approximately one in seven infants born to mothers infected during pregnancy, ZIKV has been linked to microcephaly, developmental delays, or other congenital disorders collectively known as congenital Zika syndrome (CZS). Guillain-Barre syndrome (GBS) in ZIKV infected adults. It is a global health priority to develop a vaccine against ZIKV that elicits long-lasting immunity, however, the durability of immunity to ZIKV is unknown. Previous studies in mice and nonhuman primates have been crucial in vaccine development but have not defined the duration of immunity generated by ZIKV infection. In this study, we rechallenged five rhesus macaques with ZIKV two years after a primary ZIKV infection. We show that primary ZIKV infection generates high titers of neutralizing antibodies (nAbs) that protect from detectable plasma viremia following rechallenge and persist for at least 27 months. While additional longitudinal studies are necessary with longer time frames, this study establishes a new experimentally defined minimal length of protective ZIKV immunity.\n\nAuthor SummaryZIKV emerged as a vector-borne pathogen capable of causing illness in infected adults and congenital birth defects in infants born to mothers infected during pregnancy. Despite the drop in ZIKV cases since the 2015-16 epidemic, questions concerning the prevalence and longevity of protective immunity have left vulnerable communities fearful that they may become the center of next ZIKV outbreak. While pre-existing herd immunity in regions of past outbreaks may dampen the potential for future outbreaks to occur, we currently do not know the longevity of protective immunity to ZIKV after a person becomes infected. Here, we establish a new experimentally defined minimal length of protective ZIKV immunity. We show that five rhesus macaques initially infected with ZIKV two years prior to rechallenge elicit a durable immune response that protected from detectable plasma viremia. While this work establishes a new minimal length of protective immunity, additional studies are necessary to define the maximum length of protective immunity following ZIKV infection.

immunology↗

bioRxiv2019

Extensive CD8β depletion does not prevent control of viral replication or protection from challenge in macaques chronically infected with a live attenuated simian immunodeficiency virus

We evaluated the contribution of CD8{beta}+ T cells on control of live-attenuated simian immunodeficiency virus (LASIV) replication during chronic infection and subsequent protection from pathogenic SIV challenge. Unlike previous reports with a CD8-specific depleting monoclonal antibody (mAb), the CD8{beta}-specific mAb CD8{beta}255R1 selectively depleted CD8{beta}+ T cells without also depleting non-CD8+ T cell populations that express CD8, such as natural killer (NK) cells and {gamma}{delta} T cells. Following infusion with CD8{beta}255R1, plasma viremia transiently increased coincident with declining peripheral CD8{beta}+ T cells. Interestingly, plasma viremia returned to pre-depletion levels even when peripheral CD8{beta}+ T cells did not. Although depletion of CD8{beta}+ T cells in the lymph node (LN) was incomplete, frequencies of these cells were three-fold lower (p=0.006) in animals that received CD8{beta}255R1 compared to control IgG. It is possible that these residual SIV-specific CD8{beta}+ T cells may have contributed to suppression of viremia during chronic infection. We also determined whether infusion of CD8{beta}255R1 in the LASIV-vaccinated animals increased their susceptibility to infection following intravenous challenge with pathogenic SIVmac239. We found that 7/8 animals infused with CD8{beta}255R1, and 3/4 animals infused with the control IgG, were resistant to SIVmac239 infection. These results suggest that infusion with CD8{beta}255R1 did not eliminate the protection afforded to LASIV vaccination. This provides a comprehensive description of the impact of CD8{beta}255R1 infusion on the immunological composition of the host, when compared to an isotype matched control IgG, while showing that the control of LASIV viremia and protection from challenge can occur even after CD8{beta}255R1 administration.\n\nImportanceStudies of SIV-infected macaques that deplete CD8+ T cells in vivo with monoclonal antibodies have provided compelling evidence for their direct antiviral role. These studies utilized CD8-specific mAbs that target both the major (CD8{beta}+) and minor (CD8+) populations of CD8+ T cells, but additionally deplete non-CD8+ T cell populations that express CD8, such as NK cells and {gamma}{delta} T cells. In the current study, we administered the CD8{beta}-specific depleting mAb CD8{beta}255R1 to cynomolgus macaques chronically infected with a LASIV to selectively deplete CD8{beta}+ T cells without removing CD8+ lymphocytes. We evaluated the impact on control of virus replication and protection from pathogenic SIVmac239 challenge. These results underscore the utility of CD8{beta}255R1 for studying the direct contribution of CD8{beta}+ T cells in various disease states.

immunology↗

bioRxiv2018

Acute-phase CD4+ T cell responses targeting invariant viral regions are associated with control of live-attenuated simian immunodeficiency virus

We manipulated SIVmac239{Delta}nef, a model of MHC-independent viral control, to evaluate characteristics of effective cellular responses mounted by Mauritian cynomolgus macaques (MCMs) who express the M3 MHC haplotype that has been associated with poor control of pathogenic SIV. We created SIV{Delta}nef-8x to test the hypothesis that effective SIV-specific T cell responses targeting invariant viral regions can emerge in the absence of immunodominant CD8+ T cell responses targeting variable epitopes, and that control is achievable in individuals lacking known protective MHC alleles. Full proteome IFN{gamma} ELISPOT assays identified six newly targeted immunogenic regions following SIV{Delta}nef-8x infection of M3/M3 MCMs. We deep sequenced circulating virus and found that four of the six newly targeted regions rarely accumulated mutations. Six animals infected with SIV{Delta}nef-8x targeted at least one of the four invariant regions and had a lower set point viral load compared to two animals that did not target any invariant regions. We found that MHC class II molecules restricted all four of the invariant peptide regions, while the two variable regions were restricted by MHC class I molecules. Therefore, in the absence of immunodominant CD8+ T cell responses that target variable regions during SIVmac239{Delta}nef infection, individuals without protective MHC alleles developed predominantly CD4+ T cell responses specific for invariant regions that may improve control of virus replication. Our results provide some evidence that antiviral CD4+ T cells during acute SIV infection can contribute to effective viral control and should be considered in strategies to combat HIV infection.\n\nImportanceStudies defining effective cellular immune responses to human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) have largely focused on a rare population that express specific MHC class I alleles and control virus replication in the absence of antiretroviral treatment. This leaves in question whether similar effective immune responses can be achieved in the larger population. The majority of HIV-infected individuals mount CD8+ T cell responses that target variable viral regions that accumulate high-frequency escape mutations. Limiting T cell responses to these variable regions and targeting invariant viral regions, similar to observations in rare elite controllers, may provide an ideal strategy for the development of effective T cell responses in individuals with diverse MHC genetics. Therefore, it is paramount to determine whether T cell responses can be redirected towards invariant viral regions in individuals without protective MHC alleles and if these responses improve control of virus replication.

immunology↗

bioRxiv2017

Molecularly barcoded Zika virus libraries to probe in vivo evolutionary dynamics

Defining the complex dynamics of Zika virus (ZIKV) infection in pregnancy and during transmission between vertebrate hosts and mosquito vectors is critical for a thorough understanding of viral transmission, pathogenesis, immune evasion, and potential reservoir establishment. Within-host viral diversity in ZIKV infection is low, which makes it difficult to evaluate infection dynamics. To overcome this biological hurdle, we constructed a molecularly barcoded ZIKV. This virus stock consists of a \"synthetic swarm\" whose members are genetically identical except for a run of eight consecutive degenerate codons, which creates approximately 64,000 theoretical nucleotide combinations that all encode the same amino acids. Deep sequencing this region of the ZIKV genome enables counting of individual barcode clonotypes to quantify the number and relative proportions of viral lineages present within a host. Here we used these molecularly barcoded ZIKV variants to study the dynamics of ZIKV infection in pregnant and non-pregnant macaques as well as during mosquito infection/transmission. The barcoded virus had no discernible fitness defects in vivo, and the proportions of individual barcoded virus templates remained stable throughout the duration of acute plasma viremia. ZIKV RNA also was detected in maternal plasma from a pregnant animal infected with barcoded virus for 64 days. The complexity of the virus population declined precipitously 8 days following infection of the dam, consistent with the timing of typical resolution of ZIKV in non-pregnant macaques, and remained low for the subsequent duration of viremia. Our approach showed that synthetic swarm viruses can be used to probe the composition of ZIKV populations over time in vivo to understand vertical transmission, persistent reservoirs, bottlenecks, and evolutionary dynamics.\n\nAuthor summaryUnderstanding the complex dynamics of Zika virus (ZIKV) infection during pregnancy and during transmission to and from vertebrate host and mosquito vector is critical for a thorough understanding of viral transmission, pathogenesis, immune evasion, and reservoir establishment. We sought to develop a virus model system for use in nonhuman primates and mosquitoes that allows for the genetic discrimination of molecularly cloned viruses. This \"synthetic swarm\" of viruses incorporates a molecular barcode that allows for tracking and monitoring individual viral lineages during infection. Here we infected rhesus macaques with this virus to study the dynamics of ZIKV infection in nonhuman primates as well as during mosquito infection/transmission. We found that the proportions of individual barcoded viruses remained relatively stable during acute infection in pregnant and nonpregnant animals. However, in a pregnant animal, the complexity of the virus population declined precipitously 8 days following infection, consistent with the timing of typical resolution of ZIKV in non-pregnant macaques, and remained low for the subsequent duration of viremia.

microbiology↗

bioRxiv2017

Ocular and uteroplacental pathology in macaque congenital Zika virus infection

Congenital Zika virus (ZIKV) infection impacts fetal development and pregnancy outcomes. We infected a pregnant rhesus macaque with a Puerto Rican ZIKV isolate in the first trimester. The pregnancy was complicated by preterm premature rupture of membranes (PPROM) and fetal demise 49 days post infection (gestational day 95). Significant pathology at the maternal-fetal interface included acute chorioamnionitis, placental infarcts, and leukocytoclastic vasculitis of the myometrial radial arteries. ZIKV RNA was disseminated throughout the fetus tissues and maternal immune system at necropsy, as assessed by quantitative RT-PCR for viral RNA. Replicating ZIKV was identified in fetal tissues, maternal lymph node, and maternal spleen by fluorescent in situ hybridization for viral replication intermediates. Fetal ocular pathology included a choroidal coloboma, suspected anterior segment dysgenesis, and a dysplastic retina. This is the first report of ocular pathology and prolonged viral replication in both maternal and fetal tissues following congenital ZIKV infection in rhesus macaques. PPROM followed by fetal demise and severe pathology of the visual system have not been described in macaque congenital infection previously; further nonhuman primate studies are needed to determine if an increased risk for PPROM is associated with congenital Zika virus infection.\n\nAuthor summaryA ZIKV infection during pregnancy is associated with malformations in fetal development including, but not limited to, ocular and brain anomalies, such as microcephaly, and stillbirth. The development of an accurate pregnancy model to study the effects of ZIKV will provide insight into vertical transmission, ZIKV tissue distribution, and fetal injury and malformations. Non-human primates closely resemble human in terms of the reproductive system, immunity, placentation and pregnancy. Our study demonstrates that the rhesus macaque is a compelling model in which to study ZIKV during pregnancy due to similar outcomes between the human and rhesus macaque. These similarities include prolonged viremia, vertical transmission, adverse pregnancy outcomes and fetal pathology, including defects in the visual system.

pathology↗

bioRxiv2017

Highly efficient maternal-fetal Zika virus transmission in pregnant rhesus macaques

Infection with Zika virus (ZIKV) is associated with human congenital fetal anomalies. To model fetal outcomes in nonhuman primates, we administered Asian-lineage ZIKV subcutaneously to four pregnant rhesus macaques. While non-pregnant animals clear viremia within 10-12 days, maternal viremia was prolonged in 3 of 4 pregnancies. Fetal head growth velocity in the last month of gestation determined by ultrasound assessment of head circumference was decreased in comparison with biparietal diameter and femur length within each fetus, both within normal range. ZIKV RNA was detected in tissues from all four fetuses at term cesarean section. In all pregnancies, neutrophilic infiltration was present at the maternal-fetal interface (decidua, placenta, fetal membranes), in various fetal tissues, and in fetal retina, choroid, and optic nerve (first trimester infection only). Consistent vertical transmission in this primate model may provide a platform to assess risk factors and test therapeutic interventions for interruption of fetal infection.

pathology↗

bioRxiv2017

Oropharyngeal mucosal transmission of Zika virus in rhesus macaques

Zika virus (ZIKV) is present in urine, saliva, tears, and breast milk, but the transmission risk associated with these body fluids is currently unknown. We evaluated the risk of ZIKV transmission through mucosal contact in rhesus macaques. Application of high-dose ZIKV directly to the tonsils of 3 rhesus macaques resulted in detectable plasma viremia in all animals by 2 days post-exposure; virus replication kinetics were similar to those observed in animals infected subcutaneously. Three additional macaques inoculated subcutaneously with ZIKV served as saliva donors to assess the transmission risk from contact with oral secretions from an infected individual. Seven naive animals repeatedly exposed to donor saliva via the conjunctivae, tonsils, or nostrils did not become infected. Our results suggest that there is a risk of ZIKV transmission via the mucosal route, but that the risk posed by oral secretions from individuals with a typical course of ZIKV infection is low.

microbiology↗