Measles viruses continue to spread globally, despite the availability of a safe and effective vaccine. Molecular surveillance of measles virus has become an essential tool to demonstrate whether cascades of infections in a certain region or country are the result of endemic spread or the repeatedly introduction of the virus in contained outbreaks. Currently, molecular surveillance of measles viruses worldwide is mainly based on 450 nucleotides of the C-terminal region of the nucleoprotein (N450). However, as a result of the disappearance of particular measles virus clades over the past decades, this gene segment does not provide sufficient resolution anymore to answer these questions. To increase the molecular resolution, sequence data were collected from three regions of the measles virus genome, the partial non-coding region between the M and F gene (M-F NCR4465-4754), partial H gene (H8022-8621) and the partial L gene (L10724-11438) for measles viruses detected in 2018 and 2019 in the Netherlands. Analysis of obtained sequence data indicated that sequencing of these three regions resulted in an increase in molecular resolution for measles virus genotype B3 and D8 viruses, two of the four global genotypes currently predominant in the European region. Furthermore, this improved resolution was sufficient to support an epidemiology characterized by repeat introduction of measles virus rather than endemic virus spread. In conclusion, sequencing of the M-F NCR4465-4754, H8022-8621 and L10724-11438 regions of the measles virus is an efficient and useful approach for molecular surveillance of measles viruses.

TP53 harbors somatic mutations in more than half of human tumors with some showing characteristic mutation spectra that have been linked to environmental exposures. In bladder cancer, a unique distribution of mutations amongst several codons of TP53 has been hypothesized to be caused by environmental carcinogens including 4-aminobiphenyl (4-ABP). 4-ABP undergoes metabolic activation to N-hydroxy-4-aminobiphenyl (N-OH-4-ABP) and forms pre-mutagenic adducts in DNA, of which N-(deoxyguanosin-8-yl)-4-ABP (dG-C8-4-ABP) is the major one. Human TP53 knock-in mouse embryo fibroblasts (HUFs) are a useful model to study the influence of environmental carcinogens on TP53-mutagenesis. By performing the HUF immortalization assay (HIMA) TP53-mutant HUFs are generated and mutations can be identified by sequencing. Here we studied the induction of mutations in human TP53 after treatment of primary HUFs with N-OH-4-ABP. In addition, mutagenicity in the bacterial lacZ reporter gene and the formation of dG-C8-4-ABP, measured by 32 P-postlabelling analysis, were determined in N-OH-4-ABP-treated primary HUFs. A total of 6% TP53-mutants were identified after treatment with 40 μM N-OH-4-ABP for 24 hr (n = 150) with G>C/C>G transversion being the main mutation type. The mutation spectrum found in the TP53 gene of immortalized N-OH-4-ABP-treated HUFs was unlike the one found in human bladder cancer. DNA adduct formation (~40 adducts/108 nucleotides) was detected after 24 hr treatment with 40 μM N-OH-4-ABP, but lacZ mutagenicity was not observed. Adduct levels decreased substantially (sixfold) after a 24 hr recovery period indicating that primary HUFs can efficiently repair the dG-C8-4-ABP adduct possibly before mutations are fixed. In conclusion, the observed difference in the N-OH-4-ABP-induced TP53 mutation spectrum to that observed in human bladder tumors do not support a role of 4-ABP in human bladder cancer development.