Biology subjects

Schleiss, M. R.

Publications and source records attributed to Schleiss, M. R..

4 recordsLinked to original sources

bioRxiv2025

Replication-Deficient Whole-Virus Vaccines Against Cytomegalovirus Induce Protective Immunity in a Guinea Pig Congenital Infection Model

Vaccines are needed to prevent congenital cytomegalovirus (CMV) infections. This study used the guinea pig cytomegalovirus (GPCMV) model to examine replication-deficient whole-virus vaccines against maternal viremia and congenital infection. Two recombinant GPCMVs, GP51-DD and GP52-DD, were engineered with destabilization domains fused to essential viral late proteins GP51 and GP52. These viruses, predicted to replicate in the presence of the synthetic ligand Shield-1 but not in its absence, were evaluated for Shield-1-dependence in vitro and for safety, immunogenicity, and efficacy in a pregnancy/challenge model. GP52-DD was profoundly Shield-1-dependent, producing no detectable infectious progeny in its absence. In contrast, the replication of GP51-DD was delayed in the absence of Shield-1, but the virus reached similar peak titers with or without the compound. GPCMV-seronegative guinea pigs received two subcutaneous injections of placebo (sham-immunized), GP51-DD, GP52-DD, or wild-type GPCMV (WT-GPCMV). DNAemia post-vaccination was detected in only one of 14 dams in each of the GP51-DD- and GP52-DD-immunized groups compared to 10/10 control animals immunized with WT-GPCMV, confirming the recombinant viruses were attenuated. GPCMV-specific antibody responses were similar in all three vaccinated groups. When immunized dams were bred and challenged with virulent GPCMV, DNAemia was detected in all sham-immunized controls and in 44% of GP52-DD-immunized dams (at significantly reduced levels) but was absent in dams immunized with GP51-DD or WT-GPCMV. Notably, immunization with GP52-DD, GP51-DD, or WT-GPCMV significantly reduced congenital GPCMV transmission (protective efficacies of 89%, 94%, and 100%, respectively). Thus, the replication-deficient GP52-DD vaccine was attenuated and protected against intrauterine GPCMV transmission. ImportanceCongenital cytomegalovirus (CMV) infections could be prevented by a vaccine, but most of the vaccine designs that have advanced to clinical trials have been subunit vaccines. These viral envelope glycoprotein-targeting designs have not yielded an effective vaccine that provides durable immunity. A vaccine that confers immune responses to a broader repertoire of viral immunogens, such as vaccines based on the whole virus, could enhance protection. However, there are concerns about the safety of live attenuated CMV vaccines. Using the guinea pig/guinea pig cytomegalovirus model of congenital infection, this study demonstrates that two replication-deficient whole virus vaccines are attenuated in animals while also being highly immunogenic, providing protective immunity against maternal viremia and fetal infection at levels similar to that conferred by a wild-type virus.

immunology↗

bioRxiv2024

CD4+ but not CD8+ T cells are required for protection against severe guinea pig cytomegalovirus infections

Human cytomegalovirus (HCMV) is a ubiquitous herpesvirus and the leading cause of infectious disease related birth defects worldwide. How the immune response modulates the risk of intrauterine transmission of HCMV after maternal infection remains poorly understood. Maternal T cells likely play a critical role in preventing infection at the maternal-fetal interface and limiting spread across the placenta, but concerns exist that immune responses to infection may also cause placental dysfunction and adverse pregnancy outcomes. This study investigated the role of CD4+ and CD8+ T cells in a guinea pig model of primary cytomegalovirus infection. Monoclonal antibodies specific to guinea pig CD4 and CD8 were used to deplete T cells in non- pregnant and in pregnant guinea pigs after mid-gestation. CD4+ T cell depletion increased the severity of illness, caused significantly elevated viral loads, and increased the rate of congenital guinea pig cytomegalovirus (GPCMV) infection relative to animals treated with control antibody. CD8+ T cell depletion was comparably well tolerated and did not significantly affect the weight of infected guinea pigs or viral loads in their blood or tissue. However, significantly more viral genomes and transcripts were detected in the placenta and decidua of CD8+ T cell depleted dams post-infection. This study corroborates earlier findings made in nonhuman primates that maternal CD4+ T cells play a critical role in limiting the severity of primary CMV infection during pregnancy while also revealing that other innate and adaptive immune responses can compensate for an absent CD8+ T cell response in -CD8-treated guinea pigs. Author SummaryCongenital cytomegalovirus infection is a leading cause of adverse pregnancy outcomes and preventable disability in children. Using guinea pigs, a well-established small animal model of congenital infection and intrauterine development, this study tested how depleting T cells affects the course of primary cytomegalovirus infections. Severe illness and high rates of congenital infection were observed when helper CD4+ T cells were depleted. The depletion of killer CD8+ T cells did not affect the severity of disease or the rate of congenital infection but did increase the amount of virus that was detected in the placenta. A greater understanding how an immune response can prevent the infection of the placenta and developing offspring is needed to inform vaccine and therapeutic development. This study not only describes a new reagent that can be used to study the guinea pig immune system but also sheds new light in how adaptive immunity regulates congenital viral infection.

immunology↗

bioRxiv2023

Human Cytomegalovirus in breast milk is associated with milk composition, the infant gut microbiome, and infant growth

Human cytomegalovirus (CMV) is a highly prevalent herpesvirus that is often transmitted to the neonate via breast milk. Postnatal CMV transmission can have negative health consequences for preterm and immunocompromised infants, but any effects on healthy term infants are thought to be benign. Furthermore, the impact of CMV on the composition of the hundreds of bioactive factors in human milk has not been tested. Here, we utilize a cohort of exclusively breastfeeding full term mother-infant pairs to test for differences in the milk transcriptome and metabolome associated with CMV, and the impact of CMV in breast milk on the infant gut microbiome and infant growth. We find upregulation of the indoleamine 2,3-dioxygenase (IDO) tryptophan-to-kynurenine metabolic pathway in CMV+ milk samples, and that CMV+ milk is associated with decreased Bifidobacterium in the infant gut. Our data indicate a complex relationship between milk CMV, milk kynurenine, and infant growth; with kynurenine positively correlated, and CMV viral load negatively correlated, with infant weight-for-length at 1 month of age. These results suggest CMV transmission, CMV-related changes in milk composition, or both may be modulators of full term infant development.

genomics↗

bioRxiv2020

Zika virus-based immunotherapy enhances long-term survival of rodents with brain tumors through upregulation of memory T-cells

Zika virus (ZIKV) exhibits a tropism for brain tumor cells and has been used as an oncolytic virus to target brain tumors in mice with modest effects on extending median survival. Recent studies have highlighted the potential for combining virotherapy and immunotherapy to target cancer. We postulated that ZIKV could be used as an adjuvant to enhance the long-term survival of mice with malignant glioblastoma and generate memory T-cells capable of providing long-term immunity against cancer remission. To test this hypothesis mice bearing malignant intracranial GL261 tumors were subcutaneously vaccinated with irradiated GL261 cells previously infected with the ZIKV. Mice also received intracranial injections of live ZIKV, irradiated ZIKV, or irradiated GL261 cells previously infected with ZIKV. Long-term survivors were rechallenged with a second intracranial tumor to examine their immune response and look for the establishment of protective memory T-cells. Mice with subcutaneous vaccination plus intracranial irradiated ZIKV or intracranial irradiated GL261 cells previously infected with ZIKV exhibited the greatest extensions to overall survival. Flow cytometry analysis of immune cells within the brains of long-term surviving mice after tumor rechallenge revealed an upregulation in the levels of T-cells, including CD4+ and tissue-resident memory CD4+ T-cells, in comparison to long-term survivors that were mock-rechallenged, and in comparison to naive untreated mice challenged with intracranial gliomas. These results suggest that ZIKV can serve as an adjuvant to subcutaneous tumor vaccines that enhance long-term survival and generate protective tissue-resident memory CD4+ T-cells.

cancer biology↗