Humoral and cellular responses to repeated COVID-19 exposure in multiple sclerosis patients receiving B-cell depleting therapies: a single-center, one-year, prospective study.

Multiple sclerosis patients treated with anti-CD20 therapy (aCD20-MS) are considered especially vulnerable to complications from SARS-CoV-2 infection due to severe B-cell depletion with limited viral antigen-specific immunoglobulin production. Therefore, multiple vaccine doses as part of the primary vaccination series and booster updates have been recommended for this group of immunocompromised individuals. Even though much less studied than antibody-mediated humoral responses, T-cell responses play an important role against CoV-2 infection and are induced efficiently in vaccinated aCD20-MS patients. For individuals with such decoupled adaptive immunity, an understanding of the contribution of T-cell mediated immunity is essential to better assess protection against CoV-2 infection. Here, we present results from a prospective, single-center study for the assessment of humoral and cellular immune responses induced in aCD20-MS patients (203 donors/350 samples) compared to a healthy control group (43/146) after initial exposure to CoV-2 spike antigen and subsequent re-challenges. Low rates of seroconversion and RBD-hACE2 blocking activity were observed in aCD20-MS patients, even after multiple exposures (responders after 1st exposure = 17.5%; 2nd exposure = 29.3%). Regarding cellular immunity, an increase in the number of spike-specific monofunctional IFNγ+-, IL-2+-, and polyfunctional IFNγ+/IL-2+-secreting T-cells after 2nd exposure was found most noticeably in healthy controls. Nevertheless, a persistently higher T-cell response was detected in aCD20-MS patients compared to control individuals before and after re-exposure (mean fold increase in spike-specific IFNγ+-, IL-2+-, and IFNγ+/IL-2+-T cells before re-exposure = 3.9X, 3.6X, 3.5X/P< 0.001; after = 3.2X, 1.4X, 2.2X/P = 0.002, P = 0.05, P = 0.004). Moreover, cellular responses against sublineage BA.2 of the currently circulating omicron variant were maintained, to a similar degree, in both groups (15-30% T-cell response drop compared to ancestral). Overall, these results highlight the potential for a severely impaired humoral response in aCD20-MS patients even after multiple exposures, while still generating a strong T-cell response. Evaluating both humoral and cellular responses in vaccinated or infected MS patients on B-cell depletion therapy is essential to better assess individual correlations of immune protection and has implications for the design of future vaccines and healthcare strategies.

Strong T-cell activation in response to COVID-19 vaccination in multiple sclerosis patients receiving B-cell depleting therapies.

Immunocompromised individuals, including multiple sclerosis (MS) patients on certain immunotherapy treatments, are considered susceptible to complications from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and specific vaccination regimens have been recommended for suitable protection. MS patients receiving anti-CD20 therapy (aCD20-MS) are considered especially vulnerable due to acquired B-cell depletion and impaired antibody production in response to virus infection and COVID-19 vaccination. Here, the humoral and cellular responses are analyzed in a group of aCD20-MS patients (n=43) compared to a healthy control cohort (n=34) during the first 6 months after a 2-dose cycle mRNA-based COVID-19 vaccination. Both IgG antibodies recognizing receptor binding domain (RBD) from CoV-2 spike protein and their blocking activity against RBD-hACE2 binding were significantly reduced in aCD20-MS patients, with a seroconversion rate of only 23.8%. Interestingly, even under conditions of severe B-cell depletion and failed seroconversion, a significantly higher polyfunctional IFNγ+ and IL-2+ T-cell response and strong T-cell proliferation capacity were detected compared to controls. Moreover, no difference in T-cell response was observed between forms of disease (relapsing remitting- vs progressive-MS), anti-CD20 therapy (Rituximab vs Ocrelizumab) and type of mRNA-based vaccine received (mRNA-1273 vs BNT162b2). These results suggest the generation of a partial adaptive immune response to COVID-19 vaccination in B-cell depleted MS individuals driven by a functionally competent T-cell arm. Investigation into the role of the cellular immune response is important to identifying the level of protection against SARS-CoV-2 in aCD20-MS patients and could have potential implications for future vaccine design and application.

Inhibition of the Super Elongation Complex Suppresses Herpes Simplex Virus Immediate Early Gene Expression, Lytic Infection, and Reactivation from Latency.

Induction of herpes simplex virus (HSV) immediate early (IE) gene transcription promotes the initiation of lytic infection and reactivation from latency in sensory neurons. IE genes are transcribed by the cellular RNA polymerase II (RNAPII) and regulated by multiple transcription factors and coactivators. The HCF-1 cellular coactivator plays a central role in driving IE expression at multiple stages through interactions with transcription factors, chromatin modulation complexes, and transcription elongation components, including the active super elongation complex/P-TEFb (SEC-P-TEFb). Here, we demonstrate that the SEC occupies the promoters of HSV IE genes during the initiation of lytic infection and during reactivation from latency. Specific inhibitors of the SEC suppress viral IE expression and block the spread of HSV infection. Significantly, these inhibitors also block the initiation of viral reactivation from latency in sensory ganglia. The potent suppression of IE gene expression by SEC inhibitors indicates that transcriptional elongation represents a determining rate-limiting stage in HSV IE gene transcription and that the SEC plays a critical role in driving productive elongation during both phases of the viral life cycle. Most importantly, this supports the model that signal-mediated induction of SEC-P-TEFb levels can promote reactivation of a population of poised latent genomes.IMPORTANCE HSV infections can cause pathologies ranging from recurrent lesions to significant ocular disease. Initiation of lytic infection and reactivation from latency in sensory neurons are dependent on the induced expression of the viral immediate early genes. Transcription of these genes is controlled at multiple levels, including modulation of the chromatin state of the viral genome and appropriate recruitment of transcription factors and coactivators. Following initiation of transcription, IE genes are subject to a key regulatory stage in which transcriptional elongation rates are controlled by the activity of the super elongation complex. Inhibition of the SEC blocks both lytic infection and reactivation from latency in sensory neurons. In addition to providing insights into the mechanisms controlling viral infection and reactivation, inhibitors of critical components such as the SEC may represent novel antivirals.

Transcriptional Elongation of HSV Immediate Early Genes by the Super Elongation Complex Drives Lytic Infection and Reactivation from Latency.

The cellular transcriptional coactivator HCF-1 is required for initiation of herpes simplex virus (HSV) lytic infection and for reactivation from latency in sensory neurons. HCF-1 stabilizes the viral Immediate Early (IE) gene enhancer complex and mediates chromatin transitions to promote IE transcription initiation. In infected cells, HCF-1 was also found to be associated with a network of transcription elongation components including the super elongation complex (SEC). IE genes exhibit characteristics of genes controlled by transcriptional elongation, and the SEC-P-TEFb complex is specifically required to drive the levels of productive IE mRNAs. Significantly, compounds that enhance the levels of SEC-P-TEFb also potently stimulated HSV reactivation from latency both in a sensory ganglia model system and in vivo. Thus, transcriptional elongation of HSV IE genes is a key limiting parameter governing both the initiation of HSV infection and reactivation of latent genomes.