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Ogliastro, M.

Publications and source records attributed to Ogliastro, M..

5 recordsLinked to original sources
bioRxiv2026

Stranger Swings: Temperature-Dependent Upsides and Downsides of a Densovirus in Aedes albopictus

Vector-borne diseases remain a significant global health concern, with the invasive mosquito Aedes albopictus playing a key role in the transmission of arboviruses including dengue, chikungunya, and Zika viruses. As this species expands in novel territories, effective vector control strategies are increasingly critical. Densoviruses (DVs) have emerged as potential biological control agents, either through direct pathogenic effects on mosquito populations or via paratransgenesis. However, the influence of combined environmental factors, such as temperature and densovirus infection on mosquito life-history traits remains largely unexplored. In this study, we investigated the effects of different temperatures (28{degrees}C, 31{degrees}C, and 34{degrees}C) and exposure to the densovirus AalDV2 on the survival of Ae. albopictus and on several mosquito life-history traits including its development time, size and symmetry at adult stage. Larvae were individually reared under controlled conditions and exposed to AalDV2 or a control treatment. Temperature had a strong nonlinear effect on survival, with dramatic mortality increases at 34{degrees}C. Unexpectedly, AalDV2-infected larvae showed significantly higher survival than controls at this extreme temperature, suggesting a protective effect under thermal stress. Across all temperatures, viral infection delayed pupation in a sex-dependent manner, with females experiencing greater delays and reduced adult wing size. Quantitative PCR revealed high infection rates (>96%) across all conditions with a viral load increasing with higher temperature in a sex-dependent manner. Our findings reveal a paradoxical outcome: while AalDV2 imposes fitness costs through delayed development and reduced body size, it confers an unexpected survival advantage at the extreme temperature. This represents the first documentation of temperature-dependent protective effects by an entomopathogenic virus in mosquitoes, challenging conventional assumptions about pathogen impacts. These results have critical implications for vector biocontrol strategies in a warming climate, as densovirus deployment could inadvertently enhance mosquito resilience in heat-stressed regions. Further research is needed to elucidate the underlying mechanisms and assess the impact on mosquito population dynamics.

evolutionary biology↗
bioRxiv2022

African army ants at the forefront of virome surveillance in a remote tropical forest

In this study, we used a predator-enabled metagenomics strategy to sample the virome of a remote and difficult-to-access densely forested African tropical region. Specifically, we focused our study on the use of army ants of the genus Dorylus that are obligate collective foragers and group predators that attack and overwhelm a broad array of animal prey. Using 209 army ant samples collected from 29 colonies and the virion-associated nucleic acid-based metagenomics approach, we showed that a broad diversity of bacterial, plant, invertebrate and vertebrate viral sequences were accumulated by army ants: including sequences from 157 different viral genera in 56 viral families. This suggests that using predators and scavengers such as army ants to sample broad swathes of tropical forest viromes can shed light on the composition and the structure of viral populations of these complex and inaccessible ecosystems.

microbiology↗
bioRxiv2020

Mosquito densoviruses: the revival of a biological control agent against urban Aedes vectors of arboviruses

Urban Aedes mosquitoes are vectors of many viruses affecting human health such as Dengue, Chikungunya and Zika viruses. Insecticide resistance and environmental toxicity risks hamper the effectiveness of chemical control against these mosquito vectors. Alternative control methods, such as the use of mosquito-specific entomopathogenic viruses should be explored. Numerous studies have focused on evaluating the potential of different densoviruses species as biological control agent. However, knowledge on the extent of inter- and intra-specific variations in the susceptibility of Aedes mosquitoes to infection by different densoviruses remains insufficient. In this study, we compared infection and mortality rates induced by the Aedes albopictus densovirus 2 in different strains of Aedes albopictus and Aedes aegypti mosquitoes. The two Aedes species were different in terms of susceptibility to viral infection. Under laboratory conditions, Aedes albopictus densovirus 2 appeared more virulent for the different strains of Aedes aegypti tested than for those of Aedes albopictus. In addition, we also found significant intra-specific variation in infection and mortality rates. Thus, although even if Aedes albopictus densoviruses could be powerful biocontrol agents used in the management of urban Aedes populations, our results also call into question the use of single viral isolate as biocontrol agents.

microbiology↗
bioRxiv2020

Capsid Proteins are Necessary for Replication of a Densovirus

AO_SCPLOWBSTRACTC_SCPLOWDespite tight genetic compression, viral genomes are often organized in functional gene clusters, a modular structure that might favor their evolvability. This has greatly facilitated biotechnological developments, such as the recombinant Adeno-Associated Virus (AAV) systems for gene therapy. Following this lead, we endeavored to engineer the related insect parvovirus Junonia coenia densovirus (JcDV) to create addressable vectors for insect pest biocontrol. To enable safer manipulation of capsid mutants, we translocated the non-structural (ns) gene cluster outside the viral genome. To our dismay, this yielded a virtually non-replicable clone. We linked the replication defect to an unexpected modularity breach, as ns translocation truncated the overlapping 3 UTR of the capsid transcript (vp). We found that native vp 3UTR is necessary to high VP production, but that decreased expression do not adversely impact the expression of NS proteins, which are known replication effectors. As nonsense vp mutations recapitulate the replication defect, VP proteins appear directly implicated in the replication process. Our findings suggest intricate replication-encapsidation couplings that favor maintenance of genetic integrity. We discuss possible connections with an intriguing cis-packaging phenomenon previously observed in parvoviruses, whereby capsids preferentially package the genome from which they were expressed. IO_SCPLOWMPORTANCEC_SCPLOWDensoviruses could be used as biological control agents to manage insect pests. Such applications require in depth biological understanding and associated molecular tools. However, the genomes of these viruses remain hard to manipulate due too poorly tractable secondary structures at their extremities. We devised a construction strategy that enable precise and efficient molecular modifications. Using this approach, we endeavored to create a split clone of the Junonia coenia densovirus (JcDV) that can be used to safely study the impact of capsid mutations on host specificity. Our original construct proved to be non-functional. Fixing this defect led us to uncover that capsid proteins and their correct expression are essential for continued rolling-hairpin replication. This points to an intriguing link between replication and packaging, which might be shared with related viruses. This serendipitous discovery illustrates the power of synthetic biology approaches to advance our knowledge of biological systems.

microbiology↗