IgA binds to the AD‐2 epitope of glycoprotein B and neutralizes human cytomegalovirus

Siddiqui, Saima; Hackl, Sarah; Ghoddusi, Hamid B.; McIntosh, Megan; Gomes, Ariane; Ho, Joshua W. K.; Reeves, Matthew B.; McLean, Gary R.

doi:10.1111/imm.13286

Cited by 6 publications

(5 citation statements)

References 48 publications

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“…That said, we note that it has been demonstrated that a bivalent AD2 antibody (but not an AD4 targeted antibody) can still neutralize HCMV infection post-binding using a similar approach [48]. This appears to be partially in contrast to our data, since we have previously shown that QG1 monoclonal antibodies used in our study are targeted against AD2 [35]. That said, here we demonstrate that our AD2 antibodies are less effective at +4 °C compared to 37 °C, but without detailed side-by-side characterization of different AD2 antibodies it is not sensible to infer too many conclusions apropos the prior study.…”

Section: Discussioncontrasting

confidence: 92%

“…To investigate whether this was HCMV37-specific, we took advantage of two monoclonal antibodies directed against AD2 that we have previously reported to neutralize HCMV infection [35]. Using the same experimental approach, we incubated HCMV with QG1 IgG and IgA monoclonal antibodies directed against the AD2 epitope as before at concentrations known to promote partial neutralization.…”

Section: Resultsmentioning

confidence: 99%

“…To assess sera for neutralizing capacity by standard assay, HCMV was pre-incubated with heat-inactivated sera for 1 h and then used to infect HFFs. Alternatively, virus was incubated with anti-gB antibodies HCMV37 (abcam) or QG1 IgG and IgA monoclonal antibodies targeting AD-2 of gB that have been characterized previously [35]. After 24 h, cells were fixed and stained for IE gene expression using anti-IE (Millipore; 1 : 2000) and goat anti-mouse Alexa Fluor 568 nm (Life Technologies; 1 : 1000).…”

Section: Methodsmentioning

confidence: 99%

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A temperature-dependent virus-binding assay reveals the presence of neutralizing antibodies in human cytomegalovirus gB vaccine recipients’ sera

Gomes

Baraniak

McIntosh

et al. 2023

Journal of General Virology

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Human cytomegalovirus (HCMV) remains an important cause of mortality in immune-compromised transplant patients and following congenital infection. Such is the burden, an effective vaccine strategy is considered to be of the highest priority. The most successful vaccines to date have focused on generating immune responses against glycoprotein B (gB) – a protein essential for HCMV fusion and entry. We have previously reported that an important component of the humoral immune response elicited by gB/MF59 vaccination of patients awaiting transplant is the induction of non-neutralizing antibodies that target cell-associated virus with little evidence of concomitant classical neutralizing antibodies. Here we report that a modified neutralization assay that promotes prolonged binding of HCMV to the cell surface reveals the presence of neutralizing antibodies in sera taken from gB-vaccinated patients that cannot be detected using standard assays. We go on to show that this is not a general feature of gB-neutralizing antibodies, suggesting that specific antibody responses induced by vaccination could be important. Although we can find no evidence that these neutralizing antibody responses are a correlate of protection in vivo in transplant recipients their identification demonstrates the utility of the approach in identifying these responses. We hypothesize that further characterization has the potential to aid the identification of functions within gB that are important during the entry process and could potentially improve future vaccine strategies directed against gB if they prove to be effective against HCMV at higher concentrations.

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Section: Discussioncontrasting

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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A temperature-dependent virus-binding assay reveals the presence of neutralizing antibodies in human cytomegalovirus gB vaccine recipients’ sera

Gomes

Baraniak

McIntosh

et al. 2023

Journal of General Virology

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“…Although differences in vaccine versus native gB structure may explain differences in the antibody repertoire it does not completely explain why if AD-6 can be recognized in the context of infected cells by antibodies we rarely see these antibodies in vivo. We know from studies of AD-2 that the VDJ re-arrangement required is a rare event 27,28 . However, we and others still see 50% AD-2 reactivity in HCMV seropositive individuals [29][30][31] -much higher than the 5% we report here for AD-6.…”

Section: Discussionmentioning

confidence: 99%

The cytomegalovirus gB/MF59 vaccine candidate induces antibodies against an antigenic domain controlling cell-to-cell spread

Gomes¹,

Baraniak²,

Lankina³

et al. 2023

Nat Commun

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Vaccination against human cytomegalovirus (CMV) infection remains high priority. A recombinant form of a protein essential for CMV entry, glycoprotein B (gB), demonstrated partial protection in a clinical trial (NCT00299260) when delivered with the MF59 adjuvant. Although the antibody titre against gB correlated with protection poor neutralising responses against the 5 known antigenic domains (AD) of gB were evident. Here, we show that vaccination of CMV seronegative patients induces an antibody response against a region of gB we term AD-6. Responses to the polypeptide AD-6 are detected in >70% of vaccine recipients yet in <5% of naturally infected people. An AD-6 antibody binds to gB and to infected cells but not the virion directly. Consistent with this, the AD-6 antibody is non-neutralising but, instead, prevents cell-cell spread of CMV in vitro. The discovery of AD-6 responses has the potential to explain part of the protection mediated by gB vaccines against CMV following transplantation.

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“…This analysis was designed to establish relative levels of S-and N-binding immunoglobulins contained within the NIBSC plasma preparations. We performed ELISA as described previously [15], with minor modifications. SARS-CoV-2 antigens were diluted to 1 µg/mL in PBS and coated into ELISA plate wells.…”

Section: Enzyme-linked Immunosorbent Assay (Elisa)mentioning

confidence: 99%

Rapid Quantification of SARS-CoV-2 Neutralising Antibodies Using Time-Resolved Fluorescence Immunoassay

et al. 2022

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The quantification of neutralising antibodies (NAb) for SARS-CoV-2 has become an important tool for monitoring protective immunity following infection or immunisation. In this study, we evaluated using World-Health-Organisation-standard immunoglobulin preparations, a novel point-of-care test that quantitates NAb by time-resolved fluorescent immunoassay. The assay provided robust data of binding antibody units (BAU) in 15 min that were well correlated with NAb values obtained by traditional in vitro neutralisation assay. The data also correlated well to spike-receptor-binding domain-binding antibodies over a broad range of plasma dilutions. The assay was extremely sensitive, able to detect positive samples after dilution 1:10,000 and over a wide range of BAU. Assay specificity was estimated at 96% using Pre-COVID-19 serum samples when applying a cut-off value of 47 BAU/mL, although readings of up to 100 BAU/mL could be considered borderline. This point-of-care diagnostic test is useful for rapid population screening and includes the use of capillary blood samples. Furthermore, it provides results for SARS-CoV-2 NAb in 15 min, which can inform immediate decisions regarding protective immunity levels and the need for continued COVID immunisations.

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IgA binds to the AD‐2 epitope of glycoprotein B and neutralizes human cytomegalovirus

Cited by 6 publications

References 48 publications

A temperature-dependent virus-binding assay reveals the presence of neutralizing antibodies in human cytomegalovirus gB vaccine recipients’ sera

A temperature-dependent virus-binding assay reveals the presence of neutralizing antibodies in human cytomegalovirus gB vaccine recipients’ sera

The cytomegalovirus gB/MF59 vaccine candidate induces antibodies against an antigenic domain controlling cell-to-cell spread

Rapid Quantification of SARS-CoV-2 Neutralising Antibodies Using Time-Resolved Fluorescence Immunoassay

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