Genetic and biological characterisation of Zika virus isolates from different Brazilian regions

Abstract

BACKGROUND Zika virus (ZIKV) infections reported in recent epidemics have been linked to clinical complications that had never been associated with ZIKV before. Adaptive mutations could have contributed to the successful emergence of ZIKV as a global health threat to a nonimmune population. However, the causal relationships between the ZIKV genetic determinants, the pathogenesis and the rapid spread in Latin America and in the Caribbean remain widely unknown. OBJECTIVES The aim of this study was to characterise three ZIKV isolates obtained from patient samples during the 2015/2016 Brazilian epidemics. METHODS The ZIKV genomes of these strains were completely sequenced and in vitro infection kinetics experiments were carried out in cell lines and human primary cells. FINDINGS Eight nonsynonymous substitutions throughout the viral genome of the three Brazilian isolates were identified. Infection kinetics experiments were carried out with mammalian cell lines A549, Huh7.5, Vero E6 and human monocyte-derived dendritic cells (mdDCs) and insect cells (Aag2, C6/36 and AP61) and suggest that some of these mutations might be associated with distinct viral fitness. The clinical isolates also presented differences in their infectivity rates when compared to the well-established ZIKV strains (MR766 and PE243), especially in their abilities to infect mammalian cells. MAIN CONCLUSIONS Genomic analysis of three recent ZIKV isolates revealed some nonsynonymous substitutions, which could have an impact on the viral fitness in mammalian and insect cells.

Downregulation of IGF2 expression in third trimester placental tissues from Zika virus infected women in Brazil

“…Notably, ZIKV MR766 is a laboratory-adapted strain, while the Asian isolates used in this study were recently obtained from Brazilian clinical samples not extensively passaged. 15 Remarkably, differences in the ability to downregulate IGF2 between the two recently obtained low-passage clinical Asian ZIKV isolates (ZV BR 2015/15261 and ZV BR 2016/16288) were observed. This finding was intriguing since similar RNA and percentages of cells expressing E protein were observed for both isolates ( Fig.…”

“…36 The mechanisms involved in the regulation of IGF2 gene expression by ZIKV need to be further investigated, but our results indicate the possible involvement of six amino acid differences found between the recent ZIKV clinical isolates ZV BR 2016/16288 and ZV BR 2015/15261 that map to NS1, NS2A, NS3 and NS4B proteins. 15 IGF2 expression modulation has been described for other viruses. Dysregulation of the IGF system by human papillomavirus (HPV), hepatitis B virus (HBV) and hepatitis C virus (HCV) is associated with disease progression and cancer development.…”

“…3 D). Importantly, both ZIKV ZV BR 2016/16288 and ZV BR 2015/15261 were isolated from patients exhibiting similar clinical symptoms in southern Brazil in January 2016 and northeast Brazil in June 2015, 15 respectively. Studies on the effects of ZIKV on human astrocytes have also observed similar profiles among samples, with lower IGF2 release found after astrocyte infection with ZIKV MR766 or Asian PRVABC59 Puerto Rico ZIKV strains but not with the Honduras ZIKV R103451 strain.…”

“…Caco-2 cells (ATCC HTB-37TM Homo sapiens colon colorectal cells), which tested negative for mycoplasma contamination (My-coAlert® Mycoplasma Detection kit, Lonza, Basel, Switzerland), were seeded in 6-well plates at a confluency of 5.0 x 10 5 cells per well. After incubation overnight at 37 °C and 5% CO 2 , the cells were infected with Asian-lineage ZIKV (ZV BR 2015/15261 or ZV BR 2016/16288), which had been recently isolated from clinical specimens, 15 or with the African strain ZIKV MR766 at an MOI of 1. For comparative purposes, the Caco-2 cells were either uninfected (a mock control) or infected with a DENV-1 LRV/13400 isolate, WNV E/7229/06, wild-type YFV M17/09 16 or YFV strain used for vaccines (the 17DD strain) at the same MOI.…”

Picking up a Fight: Fine Tuning Mitochondrial Innate Immune Defenses Against RNA Viruses

“…ZIKV strains from Brazil and Uganda showed delayed activation of the innate immune responses mediated by RIG-I as compared to the milder Cambodia strain that correlates with their pathological outcomes ( Esser-Nobis et al, 2019 ). Studies using these different strains in lung A549 cells revealed the important role of RIG-I sensing in early innate immune response and induction of Type I Interferon responses ( Strottmann et al, 2019 ). However, the role of this pathway in the host tropism of different isolates of ZIKV is yet to be fully uncovered that may provide a deeper insight into the importance of early viral sensing and productive IFN-response via the MAVS signalosome in ZIKV clearance.…”