Biology subjects

Karthigeyan, K. P.

Publications and source records attributed to Karthigeyan, K. P..

4 recordsLinked to original sources

bioRxiv2026

B cell response to HCMV gH/UL116 elicits neutralizing and FcγR-activating antibodies

Humoral immune mechanisms that can contribute to limiting HCMV disease include neutralizing antibodies that block viral entry and Fc-mediated effector functions that promote elimination of infected cells. Here, we identify the gH/UL116 envelope complex as a naturally immunogenic target that elicits antibodies capable of mediating both of these immune mechanisms. Using single-cell sorting of antigen-specific memory B cells, we isolated gH/UL116-reactive monoclonal antibodies from HCMV-seropositive donors. Epitope mapping showed that gH binding was required for virus neutralization, whereas UL116 targeting was associated with potent and broad Fc{gamma} receptor (Fc{gamma}R) activation. Furthermore, cryo-electron microscopy provided high-resolution structures revealing how UL116-specific antibodies bind gH/UL116. In mice, gH/UL116 immunization elicited serum IgG responses whose binding titers strongly correlated with both neutralization and mouse Fc{gamma}R activation. Together, these findings provide an epitope-level map linking antibody specificity to neutralization and Fc{gamma}R activation across HCMV gH-associated complexes and position gH/UL116 as a promising HCMV vaccine candidate.

immunology↗

bioRxiv2024

A human cytomegalovirus prefusion-like glycoprotein B subunit vaccine elicits similar humoral immunity to that of postfusion gB in mice

Human cytomegalovirus (HCMV) is the leading infectious cause of birth defects. Despite the global disease burden, there is no FDA-approved HCMV vaccine. The most efficacious HCMV vaccine candidates to date have used glycoprotein B (gB), a class III viral fusion protein, in its postfusion form. While some viral fusion proteins have been shown to elicit stronger neutralizing responses in their prefusion conformation, HCMV prefusion-like and postfusion gB were recently shown to elicit antibodies with similar fibroblast neutralization titers in mice. We aimed to define and compare the specificity and functionality of plasma IgG elicited by distinct prefusion-like and postfusion gB constructs. Prefusion-like and postfusion gB elicited comparable IgG responses that predominantly mapped to AD-5 antigenic domain known to elicit neutralizing antibodies. Interestingly, postfusion gB elicited significantly higher plasma IgG binding to cell-associated gB and antibody dependent cellular phagocytosis than that of prefusion-like gB. The vaccines elicited comparable neutralization titers of heterologous HCMV strain AD169r in fibroblasts, yet neither elicited neutralizing titers against the vaccine-matched strain Towne in fibroblasts. Our data indicate that gB in this prefusion-like conformation elicits similar specificity and functional humoral immunity to that of postfusion gB, unlike certain class I viral fusion proteins which have been used as vaccine antigens. These findings deepen our understanding of the immune response elicited by class III fusion proteins and may inform further design and testing of conformationally-dependent herpesvirus glycoprotein vaccine candidates.

immunology↗

bioRxiv2021

Heat efficiently inactivates coronaviruses inside vehicles

Heat is an established method to inactivate coronaviruses, and there is utility in using heat to reduce viral load on common touch points in vehicles exposed to a person shedding SARS-CoV-2. As SARS-CoV-2 is a Biosafety level (BSL)-3 pathogen, real world testing of heat as a sanitation method for public and private vehicles becomes a challenge, requiring a surrogate coronavirus that can be handled safely outside of a BSL-3 facility. In this study, we used Bovine Coronavirus (BCoV) as a surrogate for SARS-CoV-2 to test the efficacy of heat-based betacoronavirus inactivation. In vitro, a 30-minute exposure to 56{degrees}C completely inactivated BCoV in solution, and a 15-minute exposure reduced recovery of BCoV >1000-fold. When heated to 56{degrees}C for 15 minutes, the infectivity of BCoV spotted and dried on typical porous and non-porous automobile interior materials was reduced by 99 - 99.99%. When BCoV was spotted and dried on hard plastic (seat) material placed inside an out of service transit bus, 56{degrees}C heat for 30 minutes reduced BCoV infectivity 85 - 99.5%. Thus, 56{degrees}C is an accessible, rapid, and effective method to inactivate coronaviruses inside motor vehicles.

microbiology↗

bioRxiv2021

A bioorthogonal chemical reporter for fatty acid synthase-dependent protein acylation

Cells acquire fatty acids from dietary sources or via de novo palmitate production by fatty acid synthase (FASN). Although most cells express FASN at low levels, it is upregulated in cancers and during replication of many viruses. The precise role of FASN in disease pathogenesis is poorly understood, and whether de novo fatty acid synthesis contributes to host or viral protein acylation has been traditionally difficult to study. We describe a cell permeable, click-chemistry compatible alkynyl-acetate analog (Alk-4) that functions as a reporter of FASN-dependent protein acylation. In a FASN-dependent manner, Alk-4 selectively labeled the cellular protein interferon-induced transmembrane protein 3 (IFITM3) at its palmitoylation sites, and the HIV-1 matrix protein at its myristoylation site. Alk-4 metabolic labeling also enabled biotin-based purification and identification of more than 200 FASN-dependent acylated cellular proteins. Thus, Alk-4 is a useful bioorthogonal tool to selectively probe FASN-mediated protein acylation in normal and diseased states.

microbiology↗