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Background: Parvovirus B19 (B19 V) infection during pregnancy can cause adverse fetal outcomes. Our aim was to characterize both clinical and asymptomatic maternal and neonatal cases by studying virological and serological markers of B19 V infection, and to sequence the complete genome of the circulating virus in Argentina., Methods: Symptomatic patients were included based on maternal and/or fetal-neonatal signs attributable to B19 V infection during gestation. Pregnant patients were analyzed in either the timely diagnosis group (TD, samples obtained when symptoms were present and infection was suspected) or the retrospective diagnosis group (RD, samples collected immediately postpartum), and newborns were analyzed at birth. A sample of asymptomatic individuals was also analyzed. Diagnostic tests (PCR/qPCR/serology) and sequencing were performed on archived serum samples from 2018 to 2023, and clinical data were obtained from medical records., Results: We studied 328 symptomatic patients, including 185 pregnant patients (73 TD and 112 RD) and 143 newborns. Among them, we identified 27/328 (8.2 %) positive cases (B19V+): 12/73 (16.4 %) in the TD group, 6/112 (5.4 %) in the RD group, and 9/143 (6.3 %) newborns. Within the 77 mother-newborn pairs included, there were 8 (10.4 %) B19 V infections and 6 cases of vertical transmission. Additionally, B19 V infection was detected in 26/310 (8.4 %) asymptomatic patients. Phylogenetic analysis identified genotype 1a as a circulating strain in Argentina., Conclusions: Our findings highlight the need to raise awareness and enhance diagnostic approaches in Argentina to more effectively identify and manage B19 V infections during pregnancy in our region., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper, (Copyright © 2024. Published by Elsevier B.V.)

Introduction: Villous cytotrophoblast (vCTB) cells fuse to generate and maintain the syncytiotrophoblast layer required for placental development and function. Krüppel-like factor 6 (KLF6) is a ubiquitous transcription factor with an N-terminal acidic transactivation domain and a C-terminal zinc finger DNA-binding domain. KLF6 is highly expressed in placenta, and it is required for proper placental development. We have demonstrated that KLF6 is necessary for cell fusion in human primary vCTBs, and in the BeWo cell line., Materials and Methods: Full length KLF6 or a mutant lacking its N-terminal domain were expressed in BeWo cells or in primary vCTB cells isolated from human term placentas. Cell fusion, gene and protein expression, and cell proliferation were analyzed. Moreover, Raman spectroscopy and atomic force microscopy (AFM) were used to identify biochemical, topography, and elasticity cellular modifications., Results: The increase in KLF6, but not the expression of its deleted mutant, is sufficient to trigger cell fusion and to raise the expression of β-hCG, syncytin-1, the chaperone protein 78 regulated by glucose (GRP78), the ATP Binding Cassette Subfamily G Member 2 (ABCG2), and Galectin-1 (Gal-1), all molecules involved in vCTB differentiation. Raman and AFM analysis revealed that KLF6 reduces NADH level and increases cell Young's modulus. KLF6-induced differentiation correlates with p21 upregulation and decreased cell proliferation. Remarkable, p21 silencing reduces cell fusion triggered by KLF6 and the KLF6 mutant impairs syncytialization and decreases syncytin-1 and β-hCG expression., Discussion: KLF6 induces syncytialization through a mechanism that involves its regulatory transcriptional domain in a p21-dependent manner., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Purpose: Human parvovirus B19 (B19V) can cause anemia in immunocompromised patients. We aimed to investigate the presence of B19V in HIV+ adults with different CD4+ T cell counts, to recognise the frequency of B19V in these different conditions and its possible association with anemia., Methodology: We studied B19V specific IgM, IgG and DNA in 98 HIV+ patients and in 52 healthy individuals. HIV load, CD4+ counts and haemoglobin level were also determined in the patients., Results: No individual in the control group had detectable IgM, 41/52 (78.8 %) had IgG and 5/52 (9.6 %) had B19V DNA. Among HIV+ patients, we found 5/98 (5.1 %) IgM+, 66/98 (67.3 %) IgG+ and 15/98 (15.3 %) had B19V DNA (no significant differences between the two groups compared). Considering the CD4+ cell range in HIV patients, 37 had <200 CD4+ cells ml -1 , 31 had 200-500, and 30 had >500. Anti-B19V IgG prevalence in patients with >500 CD4+ cells ml -1 was significantly higher than in the rest (P=0.004) and compared to the control (P=0.046). B19V DNA concentration was always <10 3  IU ml -1 , including 5 healthy individuals and 15 HIV+ patients. There was no significant association between B19V IgM or DNA and anemia nor between B19V DNA and HIV load., Conclusions: The results indicate that B19V is not a high-risk factor for anemia in adult HIV+ patients under HAART treatment. Further studies will contribute to elucidate the mechanisms and significance of B19V DNA prevalence/persistence in adults, independently of the CD4+ cell status.