Human herpesvirus 6 (HHV-6) like other herpesviruses, expresses sequentially immediate early (IE), early, and late genes during lytic infection. Evidence of ability to establish latent infection has not been available, but by analogy with other herpesviruses it could be expected that IE genes that regulate and transactivate late genes would not be expressed. We report that peripheral blood mononuclear cells of healthy individuals infected with HHV-6 express the U94 gene, transcribed under IE conditions. Transcription of other IE genes (U16͞17, U39, U42, U81, U89͞90, U91) was not detected. To verify that U94 may play a role in the maintenance of the latent state, we derived lymphoid cell lines that stably expressed U94. HHV-6 was able to infect these cells, but viral replication was restricted. No cytopathic effect developed. Furthermore, viral transcripts were present in the first days postinfection and declined thereafter. A similar decline in the level of intracellular viral DNA also was observed. These findings are consistent with the hypothesis that the U94 gene product of HHV-6 regulates viral gene expression and enables the establishment and͞or maintenance of latent infection in lymphoid cells.
Natural killer cells are important in the control of viral infections. However, the role of NK cells during severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has previously not been identified. Peripheral blood NK cells from SARS-CoV and SARS-CoV-2 naïve subjects were evaluated for their activation, degranulation, and interferon-gamma expression in the presence of SARS-CoV and SARS-CoV-2 spike proteins. K562 and lung epithelial cells were transfected with spike proteins and co-cultured with NK cells. The analysis was performed by flow cytometry and immune fluorescence. SARS-CoV and SARS-CoV-2 spike proteins did not alter NK cell activation in a K562 in vitro model. On the contrary, SARS-CoV-2 spike 1 protein (SP1) intracellular expression by lung epithelial cells resulted in NK cell-reduced degranulation. Further experiments revealed a concomitant induction of HLA-E expression on the surface of lung epithelial cells and the recognition of an SP1-derived HLA-E-binding peptide. Simultaneously, there was increased modulation of the inhibitory receptor NKG2A/CD94 on NK cells when SP1 was expressed in lung epithelial cells. We ruled out the GATA3 transcription factor as being responsible for HLA-E increased levels and HLA-E/NKG2A interaction as implicated in NK cell exhaustion. We show for the first time that NK cells are affected by SP1 expression in lung epithelial cells via HLA-E/NKG2A interaction. The resulting NK cells’ exhaustion might contribute to immunopathogenesis in SARS-CoV-2 infection.
Eighty-nine tissue specimens from the urinary tract and prostate were analyzed for the presence and physical state of BK virus (BKV) DNA. Large T antigen gene sequences were amplified by PCR from prostate, kidney, ureter, and bladder with prevalences ranging from 50 to 83%. Sequence analysis of PCR products from the high variable BKV regulatory region showed that these tissues contained a new BKV strain (URO1). URO1 presents a duplication of part of the 68- and 39-bp elements of the viral enhancer, and a 68-bp deletion spanning part of the 39- and 63-bp enhancer elements. Six neoplastic specimens (11.5%), but none of the control tissues, contained viral DNA in amounts detectable by Southern blot hybridization (P < 0.05). The tumors positive by Southern blot hybridization harbored rearranged and/or integrated DNA sequences whose size was apparently incompatible with assembly into a viral particle. A full-length, macroscopically intact BKV early region was amplified from these tumors by PCR. The restriction pattern of the rearranged sequences was simple, suggesting that tumors were clonal and that DNA rearrangement occurred at an early stage of neoplastic initiation or progression.
To elucidate the roles of human herpesvirus (HHV)-6 primary unexplained infertile women, a prospective randomized study was conducted on a cohort of primary unexplained infertile women and a cohort of control women, with at least one successful pregnancy. HHV-6 DNA was analyzed and the percentage and immune-phenotype of resident endometrial Natural Killer (NK) cells, as the first line of defense towards viral infections, was evaluated in endometrial biopsies. Cytokine levels in uterine flushing samples were analyzed. HHV-6A DNA was found in 43% of endometrial biopsies from primary unexplained infertile women, but not in control women. On the contrary, HHV-6B DNA was absent in endometrial biopsies, but present in PBMCs of both cohorts. Endometrial NK cells presented a different distribution in infertile women with HHV6-A infection compared with infertile women without HHV6-A infection. Notably, we observed a lower percentage of endometrial specific CD56brightCD16- NK cells. We observed an enhanced HHV-6A-specific endometrial NK cell response in HHV-6A positive infertile women, with a marked increase in the number of endometrial NK cells activating towards HHV-6A infected cells. The analysis of uterine flushing samples showed an increase in IL-10 levels and a decrease of IFN-gamma concentrations in infertile women with HHV6-A infection. Our study indicates, for the first time, that HHV-6A infection might be an important factor in female unexplained infertility development, with a possible role in modifying endometrial NK cells immune profile and ability to sustain a successful pregnancy.
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