Biology subjects

Bello, A.

Publications and source records attributed to Bello, A..

5 recordsLinked to original sources

bioRxiv2026

Spatiotemporal distribution of Delta-like protein 1 during mouse pituitary ontogeny and its relationship with differentiating endocrine cell populations

Delta-like protein 1 (DLK1) is a transmembrane protein involved in the regulation of cellular differentiation and stem cell maintenance in several tissues, including the pituitary gland. Although DLK1 expression has been reported in the adult pituitary, its spatiotemporal distribution during mouse pituitary development remains incompletely characterized. The aim of this study was to analyse the distribution of DLK1 during embryonic and postnatal development of the mouse pituitary gland and to characterize its relationship with hormone-producing cell populations. Immunohistochemistry was performed in Swiss albino mice from embryonic day 9.5 (e9.5) to postnatal day 15 (p15). Double immunofluorescence was used at e18.5 and p15 to examine the association of DLK1 immunoreactivity with ACTH-, TSH-, GH-, FSH- and PRL-producing cells. DLK1 immunoreactivity was detected from the earliest stages of pituitary development in Rathke's pouch and the ventral diencephalon. During embryonic development, DLK1-ir cells were widely distributed throughout adenohypophyseal and neurohypophyseal primordia. As development progressed, DLK1 immunoreactivity became progressively regionalized within the anterior, intermediate and tuberal lobes, as well as in the median eminence of the hypothalamus and the posterior pituitary lobe. Cells displaying overlapping immunoreactivity for DLK1 and all hormone-producing cell populations analysed were observed at e18.5 and p15. Semiquantitative analysis at p15 indicated that approximately 32% of adenohypophyseal cells were DLK1-immunoreactive. These findings provide a detailed description of the spatiotemporal distribution of DLK1 during mouse pituitary ontogeny and suggest that DLK1 immunoreactivity is associated with differentiating endocrine cell populations throughout pituitary development.

Developmental Biology↗

bioRxiv2023

Omicron Spike Protein Is Vulnerable to Reduction

SARS-CoV-2 virus spike (S) protein is an envelope protein responsible for binding to the ACE2 receptor, driving subsequent entry into host cells. The existence of multiple disulfide bonds in the S protein makes it potentially susceptible to reductive cleavage. Using a tri-part split luciferase-based binding assay, we evaluated the impacts of chemical reduction on S proteins from different virus variants and found that those from the Omicron family are highly vulnerable to reduction. Through manipulation of different Omicron mutations, we found that alterations in the receptor binding module (RBM) are the major determinants of this vulnerability. Specifically we discovered that Omicron mutations facilitate the cleavage of C480-C488 and C379-C432 disulfides, which consequently impairs binding activity and protein stability. The vulnerability of Omicron S proteins suggests a mechanism that can be harnessed to treat specific SARS-CoV-2 strains.

biochemistry↗

bioRxiv2022

Validation and Establishment of a SARS-CoV-2 Lentivirus Surrogate Neutralization Assay as a pre-screening tool for the Plaque Reduction Neutralization Test

Neutralization assays are important in understanding and quantifying neutralizing antibody responses towards SARS-CoV-2. The SARS-CoV-2 Lentivirus Surrogate Neutralization Assay (SCLSNA) can be used in biosafety level 2 (BSL-2) laboratories and has been shown to be a reliable, alternative approach to the plaque reduction neutralization test (PRNT). In this study, we optimized and validated the SCLSNA to assess its ability as a comparator and pre-screening method to support the PRNT. Comparability between the PRNT and SCLSNA was determined through clinical sensitivity and specificity evaluations. Clinical sensitivity and specificity produced acceptable results with 100% (95% CI: 94-100) specificity and 100% (95% CI: 94-100) sensitivity against ancestral Wuhan spike pseudotyped lentivirus. The sensitivity and specificity against B.1.1.7 spike pseudotyped lentivirus resulted in 88.3% (95% CI: 77.8 to 94.2) and 100% (95% CI: 94-100), respectively. Assay precision measuring intra-assay variability produced acceptable results for High (1:[≥] 640 PRNT50), Mid (1:160 PRNT50) and Low (1:40 PRNT50) antibody titer concentration ranges based on the PRNT50, with %CV of 14.21, 12.47, and 13.28 respectively. Intermediate precision indicated acceptable ranges for the High and Mid concentrations, with %CV of 15.52 and 16.09, respectively. However, the Low concentration did not meet the acceptance criteria with a %CV of 26.42. Acceptable ranges were found in the robustness evaluation for both intra-assay and inter-assay variability. In summary, the validation parameters tested met the acceptance criteria, making the SCLSNA method fit for its intended purpose, which can be used to support the PRNT.

scientific communication and education↗

bioRxiv2021

Exposure route, sex, and age influence disease outcome in a golden Syrian hamster model of SARS-CoV-2 infection

The emergence of Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the resultant pandemic of coronavirus disease 2019 (COVID-19) has led to over one hundred million confirmed infections, greater than three million deaths, and severe economic and social disruption. Animal models of SARS-CoV-2 are critical tools for the pre-clinical evaluation of antivirals, vaccines, and candidate therapeutics currently under urgent development to curb COVID-19-associated morbidity and mortality. The golden (Syrian) hamster model of SARS-CoV-2 infection recapitulates key characteristics of severe COVID-19, including high-titer viral replication in the upper and lower respiratory tract and the development of pathogenic lesions in the lungs. In this work we examined the influence of the route of exposure, sex, and age on SARS-CoV-2 pathogenesis in golden hamsters. We report that delivery of SARS-CoV-2 primarily to the nasal passages (low-volume intranasal), the upper and lower respiratory tract (high-volume intranasal), or the digestive tract (intragastric) results in comparable viral titers in the lung tissue and similar levels of viral shedding during acute infection. However, low-volume intranasal exposure results in milder weight loss during acute infection while intragastric exposure leads to a diminished capacity to regain body weight following the period of acute illness. Further, we examined both sex and age differences in response to SARS-CoV-2 infection. Male hamsters, and to a greater extent older male hamsters, display an impaired capacity to recover from illness and a delay in viral clearance compared to females. Lastly, route of exposure, sex, and age were found to influence the nature of the host inflammatory cytokine response, but they had a minimal effect on both the quality and durability of the humoral immune response as well as the susceptibility of hamsters to SARS-CoV-2 re-infection. Together, these data indicate that the route of exposure, sex, and age have a meaningful impact SARS-CoV-2 pathogenesis in hamsters and that these variables should be considered when designing pre-clinical challenge studies.

microbiology↗

bioRxiv2020

North American deer mice are susceptible to SARS-CoV-2

The zoonotic spillover of the pandemic SARS-coronavirus 2 (SARS-CoV-2) from an animal reservoir, currently presumed to be the Chinese horseshoe bat, into a naive human population has rapidly resulted in a significant global public health emergency. Worldwide circulation of SARS-CoV-2 in humans raises the theoretical risk of reverse zoonosis events with wildlife, reintroductions of SARS-CoV-2 into permissive non-domesticated animals, potentially seeding new host reservoir species and geographic regions in which bat SARS-like coronaviruses have not historically been endemic. Here we report that North American deer mice (Peromyscus maniculatus) and some closely related members of the Cricetidae family of rodents possess key amino acid residues within the angiotensin-converting enzyme 2 (ACE2) receptor known to confer SARS-CoV-2 spike protein binding. Peromyscus rodent species are widely distributed across North America and are the primary host reservoirs of several emerging pathogens that repeatedly spill over into humans including Borrelia burgdorferi, the causative agent of Lyme disease, deer tick virus, and Sin Nombre orthohantavirus, the causative agent of hantavirus pulmonary syndrome (HPS). We demonstrate that adult deer mice are susceptible to SARS-CoV-2 infection following intranasal exposure to a human isolate, resulting in viral replication in the upper and lower respiratory tract with little or no signs of disease. Further, shed infectious virus is detectable in nasal washes, oropharyngeal and rectal swabs, and viral RNA is detectable in feces and occasionally urine. We further show that deer mice are capable of transmitting SARS-CoV-2 to naive deer mice through direct contact. The extent to which these observations may translate to wild deer mouse populations remains unclear, and the risk of reverse zoonosis and/or the potential for the establishment of Peromyscus rodents as a North American reservoir for SARS-CoV-2 is unknown. Nevertheless, efforts to monitor wild, peri-domestic Peromyscus rodent populations are likely warranted as the SARS-CoV-2 pandemic progresses.

microbiology↗