Background: Marek’s disease (MD) is a pathology affecting chickens caused by Marek’s disease virus (MDV), an acute transforming alphaherpesvirus of the genus Mardivirus. MD is characterized by paralysis, immune suppression, and the rapid formation of T-cell (primarily CD4+) lymphomas. Over the last 50 years, losses due to MDV infection have been controlled worldwide through vaccination; however, these live-attenuated vaccines are non-sterilizing and potentially contributed to the virulence evolution of MDV field strains. Mutations common to field strains that can overcome vaccine protection were identified in the C-terminal proline-rich repeats of the oncoprotein Meq (Marek’s EcoRI-Q-encoded protein). These mutations in meq have been found to be distinct to their region of origin, with high virulence strains obtained in Europe differing from those having evolved in the US. The present work reports on meq mutations identified in MDV field strains in Nigeria, arising at farms employing different vaccination practices. Materials and Methods: DNA was isolated from FTA cards obtained at 12 farms affected by increased MD in the Plateau State, Nigeria. These sequences included partial whole genomes as well as targeted sequences of the meq oncogenes from these strains. Several of the meq genes were cloned for expression and their localization ability to interact with the chicken NF-IL3 protein, a putative Meq dimerization partner, were assessed. Results: Sequence analysis of the meq genes from these Nigerian field strains revealed an RB1B-like lineage co-circulating with a European Polen5-like lineage, as well as recombinants harboring a combination of these mutations. In a number of these isolates, Meq mutations accumulated in both N-terminal and C-terminal domains. Discussion: Our data, suggest a direct effect of the vaccine strategy on the selection of Meq mutations. Moreover, we posit the evolution of the next higher level of virulence MDVs, a very virulent plus plus pathotype (vv++).

PURPOSE: Routine confirmatory testing of p16+ oropharyngeal cancers (OPCs) for human papillomavirus (HPV) mRNA is nonstandard despite evidence that negative confirmatory tests are common and may indicate poor prognosis. This study aimed to evaluate the utility of confirmatory testing by assessing the etiologies and prognostic significance of negative HPV mRNA tests in a surgically treated cohort of p16+ OPCs enriched for recurrence-prone tumors. METHODS: Fifty tumors that later recurred (cases) and 50 cured tumors (controls) were matched for key clinical features. Patients were predominantly White males with a median age of 62 years. Confirmatory testing was performed with a clinically used E6/E7 RNA in situ hybridization assay (RNAScope). RNA sequencing (RNAseq) was used to define true HPV positivity and profile HPV mRNA levels. HPV genotypes and integration were evaluated by sequencing HPV DNA and detecting HPV-host fusion mRNAs, respectively. RESULTS: Positive p16 was 100% specific for high-risk HPV mRNA expression. Content of HPV types, lineages, and sublineages did not differ significantly between cases and controls. Cases contained more frequent HPV integration based on increased HPV-host mRNA fusions ( P < .0007). False-negative confirmatory assays, which occurred in 6% (n = 6) of the cohort, were equally distributed between groups and not prognostic of survival. False negatives included three tumors containing HPV types absent from the RNAScope probe set and an episomal tumor with E6/E7 mRNA below the detection threshold by RNAseq. CONCLUSION: HPV RNAScope appears unlikely to detect HPV status misclassification or be prognostic in typical p16+ OPCs treated surgically in the United States. Confirmatory RNAScope can produce misleading false negatives in this population through various mechanisms and should be used selectively rather than routinely.