ImportanceThe SARS-CoV-2 alpha variant posed increased risk for COVID-19 complications in pregnant women. However, its impact on the maternal humoral response and placental IgG transport remains unclear.ObjectiveTo characterize the maternal humoral waning and neonate immunity acquired during the 3rd COVID-19 wave in Israel, dominated by the Alpha variant, as compared to earlier Wildtype infections and humoral response to vaccination across gestation.DesignMaternal and fetal blood serum were collected at delivery since April 2020 from parturients. Sera IgG and IgM titers were measured using the Milliplex MAP SARS-CoV-2 Antigen Panel supplemented with additional HA-coupled microspheres.SettingA nationwide multicenter cohort study on SARS-CoV-2 infections and vaccination during pregnancy.ParticipantsExpectant women presenting for delivery were recruited at 8 medical centers across Israel and assigned to 3 primary groups: SARS-CoV-2 positive (n = 157) and fully vaccinated during pregnancy (n = 125), and unvaccinated noninfected controls matched to the infected group by BMI, maternal age, comorbidities and gestational age (n = 212). Eligibility criteria included pregnant women without active COVID-19 disease, age ≥18 years and willingness to provide informed consent.Main Outcome(s) and Measure(s)Pregnant women’s humoral response is dependent on the SARS-CoV-2 strain.ResultsThe humoral response to infection as detected at birth, showed a gradual and significant decline as the interval between infection/vaccination and delivery increased. Significantly faster decay of antibody titers was found for infections occurring during the 3rd wave compared to earlier infections/vaccination. Cord blood IgG antigens levels correlated with maternal IgG. However, cord IgG-HA variance significantly differed in SARS-CoV2 infections as compared to the other groups. No sexual dimorphism in IgG transfer was observed. Lastly, high fetal IgM response to SARS-CoV-2 was detected in 17 neonates, all showing elevated IgM to N suggesting exposure to SARS-Cov-2 antigens.Conclusions and RelevanceInfections occurring during the 3rd wave induced a faster decline in humoral response when compared to Wildtype infections or mRNA BNT162b2 vaccination during pregnancy, consistent with a shift in disease etiology and severity induced by the Alpha variant. Vaccination policies in previously infected pregnant women should consider the timing of exposure along pregnancy as well as the risk of infection to specific variants of concern.Key PointsQuestionWhat is the difference in the maternal-fetal humoral response between Alpha variant and SARS-CoV-2 Wildtype infections?FindingsIn this nationwide multicenter study including 494 pregnant women, the maternal humoral response to Alpha variant infection was weaker and shorter when compared to Wildtype infections. Placental transport compensated for the maternal waning of immunity. Fetal sex did not affect humoral response.MeaningVaccination policies should be adjusted to account for the timing of infection and the SARS-CoV-2 variant.

Background Plasmodium falciparum (Pf) is the leading protozoan causing malaria, the most devastating parasitic disease. To ensure transmission, a small subset of Pf parasites differentiate into the sexual forms (gametocytes). Since the abundance of these essential parasitic forms is extremely low within the human host, little is currently known about the molecular regulation of their sexual differentiation, highlighting the need to develop tools to investigate Pf gene expression during this fundamental mechanism. Methods We developed a high-throughput quantitative Reverse-Transcription PCR (RT-qPCR) platform to robustly monitor Pf transcriptional patterns, in particular, systematically profiling the transcriptional pattern of a large panel of gametocyte-related genes (GRG). Initially, we evaluated the technical performance of the systematic RT-qPCR platform to ensure it complies with the accepted quality standards for: (i) RNA extraction, (ii) cDNA synthesis and (iii) evaluation of gene expression through RT-qPCR. We then used this approach to monitor alterations in gene expression of a panel of GRG upon treatment with gametocytogenesis regulators. Results We thoroughly elucidated GRG expression profiles under treatment with the antimalarial drug dihydroartemisinin (DHA) or the metabolite choline over the course of a Pf blood cycle (48 h). We demonstrate that both significantly alter the expression pattern of PfAP2-G, the gametocytogenesis master regulator. However, they also markedly modify the developmental rate of the parasites and thus might bias the mRNA expression. Additionally, we screened the effect of the metabolites lactate and kynurenic acid, abundant in severe malaria, as potential regulators of gametocytogenesis. Conclusions Our data demonstrate that the high-throughput RT-qPCR method enables studying the immediate transcriptional response initiating gametocytogenesis of the parasites from a very low volume of malaria-infected RBC samples. The obtained data expand the current knowledge of the initial alterations in mRNA profiles of GRG upon treatment with reported regulators. In addition, using this method emphasizes that asexual parasite stage composition is a crucial element that must be considered when interpreting changes in GRG expression by RT-qPCR, specifically when screening for novel compounds that could regulate Pf sexual differentiation. Graphical Abstract