Epstein Barr virus (EBV) infection in Argentina occurs at an early age and occasionally develops infectious mononucleosis (IM). EBV is also related with lymphomas. LMP1, the viral oncoprotein is polymorphic and is used to define viral variants.AimTo study LMP1 variants distribution among children with EBV+ malignant and benign conditions as well as in healthy carriers.MethodsOral secretions and blood cells from 31 children with IM, and biopsies from 14 EBV+ reactive lymphoid hyperplasia and 33 EBV+ lymphomas were included. LMP1 was amplified by nested PCR and sequenced. Phylogenetic reconstructions were made under Maximun Likelihood, Bayesian and coalescent algorithms.ResultsSix clades were defined (China1, China2, Med-, Alaskan, B95.8 and Argentine). Argentine variants, the most prevalent (46%), harbored 3 distinctive mutations and were a recombination between Raji and China1. Despite no pathology or compartment associations were observed for LMP1, the Argentine clade showed a phylogeographic association with our region. LMP1 estimated evolution rate was 8.591x10-5s/s/y and the estimated tMRCA for Raji and Argentine was 136ybp.ConclusionsAn LMP1 Argentine clade was defined. LMP1 evolutionary rate was higher than expected for herpesviruses. The tMRCA for Raji and the Argentine agrees with African immigration and could explain the recombinant nature of the Argentine variant.

The ubiquitous Epstein-Barr virus (EBV) is related to the development of lymphoma and is also the etiological agent for infectious mononucleosis (IM). Sequence variations in the gene encoding LMP1 have been deeply studied in different pathologies and geographic regions. Controversial results propose the existence of tumor-related variants, while others argued in favor of a geographical distribution of these variants. Reports assessing EBV variants in IM were performed in adult patients who displayed multiple variant infections. In the present study, LMP1 variants in 15 pediatric patients with IM and 20 pediatric patients with EBV-associated lymphomas from Argentina were analyzed as representatives of benign and malignant infections in children, respectively. A 3-month follow-up study of LMP1 variants in peripheral blood cells and in oral secretions of patients with IM was performed. Moreover, an integrated linkage analysis was performed with variants of EBNA1 and the promoter region of BZLF1. Similar sequence polymorphisms were detected in both pathological conditions, IM and lymphoma, but these differ from those previously described in healthy donors from Argentina and Brazil. The results suggest that certain LMP1 polymorphisms, namely, the 30-bp deletion and high copy number of the 33-bp repeats, are associated with EBV-related pathologies, either benign or malignant, instead of just being tumor related. Additionally, this is the first study to describe the Alaskan variant in EBV-related lymphomas that previously was restricted to nasopharyngeal carcinomas from North America.

Background The TREM2 R47H variant is one of the strongest genetic risk factors for late-onset Alzheimer’s Disease (AD). Unfortunately, many current Trem2R47H mouse models are associated with cryptic mRNA splicing of the mutant allele that produces a confounding reduction in protein product. To overcome this issue, we developed the Trem2R47H NSS (Normal Splice Site) mouse model in which the Trem2 allele is expressed at a similar level to the wild-type Trem2 allele without evidence of cryptic splicing products. Methods Trem2R47H NSS mice were treated with the demyelinating agent cuprizone, or crossed with the 5xFAD mouse model of amyloidosis, to explore the impact of the TREM2 R47H variant on inflammatory responses to demyelination, plaque development, and the brain’s response to plaques. Results Trem2R47H NSS mice display an appropriate inflammatory response to cuprizone challenge, and do not recapitulate the null allele in terms of impeded inflammatory responses to demyelination. Utilizing the 5xFAD mouse model, we report age- and disease-dependent changes in Trem2R47H NSS mice in response to development of AD-like pathology. At an early (4-month-old) disease stage, hemizygous 5xFAD/homozygous Trem2R47H NSS (5xFAD/Trem2R47H NSS) mice have reduced size and number of microglia that display impaired interaction with plaques compared to microglia in age-matched 5xFAD hemizygous controls. This is associated with a suppressed inflammatory response but increased dystrophic neurites and axonal damage as measured by plasma neurofilament light chain (NfL) level. Homozygosity for Trem2R47H NSS suppressed LTP deficits and loss of presynaptic puncta caused by the 5xFAD transgene array in 4-month-old mice. At a more advanced (12-month-old) disease stage 5xFAD/Trem2R47H NSS mice no longer display impaired plaque-microglia interaction or suppressed inflammatory gene expression, although NfL levels remain elevated, and a unique interferon-related gene expression signature is seen. Twelve-month old Trem2R47H NSS mice also display LTP deficits and postsynaptic loss. Conclusions The Trem2R47H NSS mouse is a valuable model that can be used to investigate age-dependent effects of the AD-risk R47H mutation on TREM2 and microglial function including its effects on plaque development, microglial-plaque interaction, production of a unique interferon signature and associated tissue damage.

The ubiquitous Epstein-Barr virus (EBV) is related to the development of several lymphoid and epithelial malignancies and is also the aetiological agent for infectious mononucleosis (IM). BZLF1, an immediate early gene, plays a key role in modulating the switch from latency to lytic replication, hence enabling viral propagation. Polymorphic variations in the coded protein have been studied in other geographical regions in a search for viral factors that are inherent to malignancies and differ from those present in benign infections. In the present study, in samples of paediatric patients with benign IM and paediatric patients with malignant lymphomas, we detected previously described sequence variations as well as distinctive sequence polymorphisms from our region. By means of phylogenetic reconstruction, we characterized new phylogenetically distinct variants. Moreover, we described an association between specific variants and the studied pathologies in our region, particularly variant BZLF1-A2 with lymphomas and BZLF1-C with IM. Additionally, length polymorphisms within intron 1 were also assessed and compared between pathologies resulting in an association between 29-bp repeated units and lymphomas. In conclusion, this is the first report to characterize BZLF1 gene polymorphisms in paediatric patients from our geographical region and to suggest the association of these polymorphisms with malignant lymphomas.