Biology subjects

Campbell, C. L.

Publications and source records attributed to Campbell, C. L..

4 recordsLinked to original sources

bioRxiv2026

Pathogenesis and host response to a novel Tacaribe virus isolate in experimentally-infected Jamaican fruit bats

Tacaribe virus (TCRV) was the first arenavirus discovered in the New World and was isolated from Artibeus bats in Trinidad and Tobago in the 1950s. One isolate, TRVL-11573, remains but it was passaged by intracranial inoculation of newborn mice 22 times that likely changed its biology. This isolate has been extensively used for arenavirus research, including our previous work that showed it can cause fatal neurological disease in Jamaican fruit bats (Artibeus jamaicensis). Another divergent TCRV, DOM2014, was recently identified in transcriptome data from a Jamaican fruit bat captured in the Dominican Republic that contained TCRV genome. A kidney fragment homogenate from this bat was inoculated into Jamaican fruit bats and all became infected with signs of mild liver disease. Experimental challenge of Jamaican fruit bats with DOM2014 led to nonfatal infection that persisted through the end of the study on day 21 and with contact transmission to naive bats. Histopathology, immunohistochemistry and serum chemistry confirmed infection and mild liver disease, but none of the bats produced neutralizing antibodies. B cell receptor transcripts suggested limited somatic hypermutation that could explain the lack of detectable neutralizing antibodies. Transcriptome profiling of livers and spleens showed signatures of a typical innate antiviral response; however, evidence of adaptive immune suppression was also present. Similarly, liver transcriptome analysis showed signatures of an expected innate antiviral response and metabolic dysfunction. The isolation of TCRV DOM2014 provides a relevant model for the study of a bat reservoir host, and which may challenge the extensive work previously conducted with TRVL-11573. IMPORTANCESeveral New World arenaviruses cause disease in humans and many are BSL-4 agents. TCRV strain TRVL-11573 has been used since the 1950s to study arenavirus biology; however, because it was intracranially passaged in newborn mice and Vero cells, it likely accumulated mutations that changed its biology. This assertion has been reinforced in recent years with discovery of divergent TCRV sequences in wild Artibeus bats that are substantially different than TRVL-11573, thus the prototype strain is unlikely to represent wildtype TCRV. The isolation of a new TCRV strain that has retained its genome fidelity allows a better understanding of TCRVs biology and pathogenic potential. The availability of pathogen-free Jamaican fruit bats and cell lines that are permissive for TCRV DOM2014 will also help retain the biological features of the virus. Collectively, this is among the most tractable bat reservoir host models developed and provides a system for dissection of how bats host viruses. Moreover, it may be a suitable model for the study of therapeutics and vaccines for New World arenaviruses.

microbiology↗

bioRxiv2025

Altered histone modifications in Aedes aegypti following Rift Valley fever virus exposure

When arthropod-borne viruses (arboviruses) are delivered to vector mosquitoes in an infectious bloodmeal, viral components interact with host proteins to hijack cells and initiate replication. The extent to which arbovirus infection alters mosquito host transcriptional and genomic regulatory processes is currently unknown. We hypothesized that histone modifications would be altered in mosquitoes exposed to Rift Valley fever virus (RVFV MP12, Phlebovirus riftense, family Phleboviridae). We interrogated transcriptome and chromatin landscapes in Aedes aegypti midguts by performing Cleavage Under Targets and Release Using Nuclease (CUT&RUN), using H3K27ac and H3K9me3 marks. Altered H3K27ac marks were identified following RVFV MP12 exposure, as well as upon bloodfeeding alone. It took several days for differential H3K27ac marks to be associated with differentially expressed genes (DEGs) in RVFV-exposed midguts. H3K27ac peaks showed progressive depletion as infection progressed. Gene set enrichment analysis revealed that immune response transcripts were enriched at 1 and 3 dpf (days post-feeding) but depleted by 7 dpf. Hedgehog/Gli (glioma-associated oncogene homolog) signaling pathway transcripts were depleted, indicating possible viral manipulation of cellular polarization. Moreover, at 7 dpf, 7 of 102 DEGs were proximal to differentially acetylated sites in a pattern expected to favor viral propagation. However, one transcript coding for an antiviral effector (LysM-TLDc domain protein) showed significant depletion of both H3K9me3 and H3K27ac marks. Analysis of midguts after a non-infectious bloodmeal versus sugar-fed controls revealed global changes to H3K27ac and H3K9me3 marks during and following the period of bloodmeal digestion. Differential H3K27ac marks were proximal to one quarter of all DEGs at 1 dpf, consistent with an important role of H3K27ac in bloodmeal digestion. These results demonstrate that H3K27ac and H3K9me3 patterns are altered upon virus exposure in a complex interplay that favors viral replication but is also countered by host responses to limit replication. Author SummaryMosquito-borne viruses produce a high disease burden across the globe. Though transgenic mosquitoes are being developed to help mitigate disease transmission, little is known of the ways in which arbovirus infection alters chromatin structure in mosquitoes. Arboviruses typically replicate and assemble on cytoplasmic membranes and have not been traditionally expected to alter processes in the nucleus. Some histone post-translational modifications, such as, e.g. histone 3 lysine 27 acetylation (H3K27ac), are associated with accessible chromatin regions, whereas others, e.g, histone 3 lysine 9 triple-methylation (H3K9me3), are associated with inaccessible chromatin. This work explores these chromatin modifications and the ways in which they are tied to gene expression changes. Multiple lines of evidence presented here support the hypothesis that H3K27ac levels change in RVFV-exposed mosquitoes and are associated with altered gene expression in a manner consistent with viral hijacking of gene expression in the nucleus. In addition, bloodfeeding alone also altered H3K27ac levels at 1-day post-feeding, and over one quarter of differentially expressed genes had changes to H3K27ac marks near transcription start sites, which is consistent with the idea that broad metabolic changes occur to support digestion and egg development.

genomics↗

bioRxiv2024

Discrimination of Jamaican fruit bat lymphocytes by flow cytometry

Bats are natural reservoir hosts of many important zoonotic viruses but because there are few immunological reagents and breeding colonies available for infectious disease research, little is known about their immune responses to infection. We established a breeding colony Jamaican fruit bats (Artibeus jamaicensis) to study bat virology and immunology. The species is used as a natural reservoir model for H18N11 influenza A virus, and as a surrogate model for SARS-CoV-2, MERS-CoV and Tacaribe virus. As part of our ongoing efforts to develop this model organism, we sought to identify commercially available monoclonal antibodies (mAb) for profiling Jamaican fruit bat lymphocytes. We identified several cross-reactive mAb that can be used to identify T and B cells; however, we were unable to identify mAb for three informative T cell markers, CD3{gamma}, CD4 and CD8. We targeted these markers for the generation of hybridomas, and identified several clones to each that can be used with flow cytometry and fluorescence microscopy. Specificity of the monoclonal antibodies was validated by sorting lymphocytes, followed by PCR identification of confirmatory transcripts. Spleens of Jamaican fruit bats possess about half the number of T cells than do human or mouse spleens, and we identified an unusual population of cells that expressed the B cell marker CD19 and the T cell marker CD3. The availability of these monoclonal antibodies will permit a more thorough examination of adaptive immune responses in Jamaican fruit bats that should help clarify how the bats control viral infections and without disease. ImportanceBats naturally host a number of viruses without disease, but which can cause significant disease in humans. Virtually nothing is known about adaptive immune responses in bats because of a lack of immunological tools to examine such responses. We have begun to address this deficiency by identifying several commercially available monoclonal antibodies to human and mouse antigens that are cross-reactive to Jamaican fruit bat lymphocyte orthologs. We also generated monoclonal antibodies to Jamaican fruit bat CD3{gamma}, CD4 and CD8 that are suitable for identifying T cell subsets by flow cytometry and immunofluorescent staining of fixed tissues. Together, these reagents will allow a more detailed examination of lymphocyte populations in Jamaican fruit bats.

immunology↗

bioRxiv2017

Improved Aedes aegypti mosquito reference genome assembly enables biological discovery and vector control

Female Aedes aegypti mosquitoes infect hundreds of millions of people each year with dangerous viral pathogens including dengue, yellow fever, Zika, and chikungunya. Progress in understanding the biology of this insect, and developing tools to fight it, has been slowed by the lack of a high-quality genome assembly. Here we combine diverse genome technologies to produce AaegL5, a dramatically improved and annotated assembly, and demonstrate how it accelerates mosquito science and control. We anchored the physical and cytogenetic maps, resolved the size and composition of the elusive sex-determining \"M locus\", significantly increased the known members of the glutathione-S-transferase genes important for insecticide resistance, and doubled the number of chemosensory ionotropic receptors that guide mosquitoes to human hosts and egg-laying sites. Using high-resolution QTL and population genomic analyses, we mapped new candidates for dengue vector competence and insecticide resistance. We predict that AaegL5 will catalyse new biological insights and intervention strategies to fight this deadly arboviral vector.

genomics↗