Depickere, S. | Search bioRxiv

bioRxiv2026

Late induction of IgG4 following SARS-CoV-2 mRNA vaccination in pregnant and non-pregnant individuals includes clonotypes raised early in the response

To better understand how pregnancy impacts humoral immunity, we conducted an in-depth longitudinal analysis of the kinetics and characteristics of vaccine responses in a prospective cohort of pregnant and non-pregnant women. Humoral immune responses observed among pregnant participants who received the mRNA-delivered SARS-CoV-2 vaccination, including their effector functions, were in some cases marginally lower than those among non-pregnant controls, while prior infection was associated with some potentiation in humoral responses. Importantly, vaccine-induced antibodies were efficiently transferred across the placenta, providing the fetus with passive immunity and underscoring the dual benefit of maternal vaccination for both mother and neonate against COVID-19. Delayed induction of spike-specific IgG4 following the primary two-dose vaccination series was observed in vaccine recipients, independent of pregnancy status. In a subset (n=6) of pregnant women whose spike-specific serum IgG repertoires were extensively profiled at the clonotypic level over time as part of another study, we proteomically identified secreted IgG clonotypes that had class-switched to IgG4. Matching of these clonotypes detected as IgG4 to those defined as SARS-CoV-2 spike-specific revealed that, while a minority of total clonotypes, they were elicited early in the immunization series and tended to be more highly mutated, more prevalent, and more persistent than clonotypes in the serological repertoire that were not detected as IgG4. Consistent with the increase in secreted vaccine-specific IgG4 over time, but its poorer placental transfer, these clonotypes were detected at greater levels in maternal but not cord blood at the time of delivery as compared to 28 days post the second vaccine dose. These findings indicate some impact in the kinetics, characteristics, and functions of the humoral response that may be associated with pregnancy-related immune modulation. Conservation of the late class-switch recombination to IgG4 that has previously been associated with mRNA-based SARS-CoV-2 vaccines raises questions about how different immunological states and vaccine components influence short- and long-term characteristics of the humoral immune response.

immunology↗

bioRxiv2023

Modeling the development of Triatoma infestans through temperature: Estimating generation time in Bolivia

BackgroundIn Bolivia, controlling Triatoma infestans, the primary vector of Chagas disease, remains challenging in the hot regions of the country. The study aims to establish a temperature-based model of development for T. infestans and explore phenological factors that could partially explain the failures in vector control within these regions of high ambient temperature. MethodsWe employed the Briere-1 model to describe the development time from egg-hatch to adults of T. infestans with temperature. Given that the entire developmental cycle can exceed two years under cooler temperature conditions, direct study of this duration was not undertaken. Instead, simulation was employed. For this purpose, insect cohorts encompassing all six stages (egg, N1, N2, N3, N4, N5) were concurrently raised within temperature-controlled climate chambers. The number of days required for molting between consecutive stages was recorded. Using this recorded dataset, the development time from eggs to adults was statistically simulated for various constant temperatures. The Briere-1 model was then calibrated using the dataset from each molting phase and applied to the simulated complete development cycle. The model was then used in conjunction with field temperatures from four representative localities within Bolivia to compute development times and generation intervals. A GIS approach was also used to map development times and generation intervals in the geographical distribution range of T. infestans. FindingsThe model suggests that the minimum temperature required for the development of T. infestans is approximately 15{degrees}C. The temperature at which its development attains maximum efficiency is around 33{degrees}C, while the threshold for lethal temperature stands at approximately 39{degrees}C. In the warmer regions of Bolivia, T. infestans exhibits an almost bivoltine cycle, with the number of yearly generations (G) ranging from approximately 1.5 to 2.5. In contrast, within the cooler Dry Inter-Andean Valleys, its cycle becomes univoltine or even less frequent (G[≤]1). The model could potentially offer insights into the correlations between insecticide resistance and the number of yearly generations, thereby clarifying why the control of T. infestans in hotter regions proves more challenging to achieve. InterpretationThe notion of generation time arises as a pivotal consideration in the management of T. infestans, especially within Bolivias warmer regions. In areas marked by higher temperatures, the generation time of the vector diminishes, leading to a notable increase in the population growth rate. This, in turn, accelerates the emergence of insecticide resistance, as evidenced by the findings of this current study. Author summaryIn Bolivia, the bug Triatoma infestans is the main carrier of Trypanosoma cruzi, the parasite responsible for Chagas disease. This study aims to understand how these bugs develop in different temperatures and how temperature affects efforts to control Chagas disease. Experiments in controlled environments with different temperatures were carried out and results revealed that the Briere-1 model can accurately imitated how the bugs growth rate changes with temperature: following a sigmoid pattern, higher temperatures make the bugs grow faster up to a maximum before slowing rapidly down. Using this model, the study looked at how long it takes for a new generation of bugs to develop and therefore estimated the generation time as a function of temperature. It appeared that in warmer places, the bugs can have more than one generation in a year, which makes their population grow quickly and increases the risk of Chagas disease spreading. The study also looked at whether the bugs resistance to insecticides is correlated to the generation time and it appeared that areas where bugs reproduce quickly tend to have more resistance to insecticides. This research emphasizes how important it is to consider temperature when trying to control T. infestans. Indeed, in areas with higher temperatures, the bugs reproduce more quickly and show a greater tendency to develop higher levels of resistance to insecticides. This dynamic complicates efforts to control them effectively. This information holds the potential to inform the development of improved strategies to curtail the spread of Chagas disease.

ecology↗

bioRxiv2018

Manipulation of the social and spatial organization of the vector of Chagas disease, Triatoma infestans, by the parasite Trypanosoma cruzi

Insects of Triatominae subfamily are vectors of the parasite Trypanosoma cruzi, the etiological agent of Chagas disease affecting millions of people in Latin America. Some of these vector species, like Triatoma infestans, live in the human neighborhood, aggregating in walls or roof cracks during the day and going out to feed on animal or human blood at night. Except for their feeding specialization, these insects share this cycle of activities with many gregarious arthropod species. The understanding of how sex and T. cruzi infection affect their aggregation and geotaxis behavior is essential for understanding the spatial organization of the insects and the parasite dispersion. Experiments with non-infected and infected adults of T. infestans show that the insects presented a high negative geotaxis and aggregative behavior. Males had a higher negative geotaxis and a higher aggregation level than females. The aggregation level and the negative geotaxis were stronger in infected insects than in non-infected ones, the difference between sexes being maintained. The importance of these results is discussed in term of parasitic manipulation, dispersion of the vector and strategy of its monitoring.

animal behavior and cognition↗