And Why That’s Actually Expected

Yoon Hang Kim, MD, MPH

Board-Certified in Preventive Medicine; Integrative & Holistic Medicine

Certified Medical Acupuncturist (UCLA) | Osher Fellow (University of Arizona)

www.DirectIntegrativeCare.com

Disclaimer: This article is for educational purposes only and does not constitute medical advice. Always consult your healthcare provider before making changes to your treatment plan.

Introduction

One of the most common questions I encounter in my LDN Support Group is a version of this: “My thyroid antibodies are the lowest they’ve ever been, and my ANA finally went negative after almost 20 years—but my EBV and CMV IgG levels haven’t budged. Some are even higher. How is that possible? I’m taking antivirals AND LDN!”

This experience is more common than most patients realize, and it does not mean that treatment is failing. In fact, the pattern of improving autoimmune markers alongside stable herpesvirus IgG titers is immunologically expected. Understanding why requires a closer look at how different types of antibodies behave and what LDN actually does at the immune level.

1. EBV and CMV IgG: A Marker of Memory, Not Active Infection

Once a person has been infected with Epstein-Barr virus (EBV) or cytomegalovirus (CMV), the immune system generates long-lived plasma cells (LLPCs) that take up residence in the bone marrow and continue producing IgG antibodies indefinitely. Research published in Nature Communications (2016) and Frontiers in Immunology (2019) has demonstrated that these LLPCs can persist for decades—potentially for the lifetime of the individual—continuously secreting antibodies regardless of whether the virus is active or dormant.

This is a critical distinction. A positive EBV VCA IgG or CMV IgG tells you that the person was infected at some point. It does not reliably indicate whether the virus is currently reactivating. IgG to these herpesviruses is fundamentally a marker of immunological memory, not disease activity.

Clinicians who specialize in herpesvirus-associated illness generally use different markers to assess viral reactivation:

• EBV Early Antigen-Diffuse (EA-D) IgG: Elevated levels suggest recent or ongoing lytic (active) replication.
• EBV Viral Capsid Antigen (VCA) IgM: A positive IgM may indicate recent primary infection or reactivation.
• EBV PCR Viral Load: Quantitative measurement of viral DNA in blood, providing direct evidence of active viral replication.
• CMV PCR: Similarly quantifies CMV DNA and is the standard for monitoring active CMV infection.

In short, if your EBV or CMV IgG titers remain unchanged, it most likely reflects the persistent, normal output of long-lived plasma cells—not treatment failure.

2. IgG Levels Can Actually Rise When Immunity Improves

This is a counterintuitive point that confuses many patients and even some clinicians. When the immune system begins to function more effectively—as can occur with LDN therapy—IgG titers to previously encountered pathogens may actually increase temporarily.

Possible mechanisms include:

• Enhanced B-cell signaling and antigen presentation: As immune surveillance improves, the immune system may recognize viral proteins more efficiently, leading to a stronger antibody output from existing memory B cells.
• Improved T-regulatory cell balance: LDN is known to modulate T-regulatory cells, which can shift the overall immune tone. This recalibration may temporarily upregulate certain antibody responses.
• Increased endorphin-mediated immune surveillance: LDN’s transient opioid receptor blockade leads to upregulation of endogenous endorphins, which in turn enhance NK cell activity and broader immune vigilance.

A rising EBV or CMV IgG in the context of improving autoimmune markers may therefore paradoxically represent better immune function, not worse.

3. LDN Modulates Autoimmunity—It Does Not Target Latent Herpesviruses

Low Dose Naltrexone works primarily by modulating the immune system through opioid receptor dynamics. Its clinical benefits in autoimmune disease are thought to involve downregulation of pro-inflammatory cytokines, improved T-regulatory cell function, and normalization of immune signaling. Clinical and anecdotal evidence consistently supports its ability to lower thyroid peroxidase (TPO) and thyroglobulin (TG) antibodies in Hashimoto’s thyroiditis, and some patients—like the one who prompted this article—experience normalization of ANA titers as well.

However, LDN has no known direct antiviral mechanism against latent herpesviruses. It does not inhibit herpesvirus DNA polymerase, interfere with viral latency programs, or clear EBV-infected memory B cells. EBV and CMV achieve latency through fundamentally different biological strategies than the autoimmune pathways LDN modulates.

The following table summarizes the expected pattern:

4. Antivirals Suppress Replication—They Do Not Eliminate Latency

A common source of frustration is the expectation that antiviral medications should bring EBV or CMV IgG levels down. In reality, even the most commonly used antivirals—valacyclovir, famciclovir, and valganciclovir—work by inhibiting viral DNA polymerase during active (lytic) replication. They have no effect on the latent viral episome that persists inside memory B cells (for EBV) or myeloid progenitor cells (for CMV).

A landmark study published in the Journal of Virology (2009) demonstrated that even after one year of valacyclovir therapy, the number of EBV DNA copies per B cell remained unchanged, despite a modest reduction in the total number of EBV-infected B cells. The half-life of EBV-infected B cells in untreated individuals was estimated at approximately 31 years, underscoring the extraordinary persistence of latent infection.

A 2022 review in Frontiers in Immunology further confirmed that nucleoside analogs have no effect on latent EBV infection because the viral enzymes required for prodrug activation are not expressed during latency. A 2025 clinical trial published in PLOS Pathogens showed that six months of valaciclovir in healthy older adults had no discernible effect on either CMV or EBV viral load.

Because IgG antibodies are produced by long-lived plasma cells in response to viral antigens they encountered long ago—not in response to current viral replication—suppressing lytic replication with antivirals would not be expected to change IgG titers.

5. Laboratory Variability: A Commonly Overlooked Factor

Before interpreting any change in IgG titers as clinically meaningful, it is important to recognize that immunoassays carry inherent variability. Inter-assay coefficient of variation for EBV and CMV IgG testing can range from 10–25% depending on the laboratory and methodology used. When coupled with normal physiological fluctuations in immune activity, a reported change of 20–40% between draws may fall entirely within the expected range of assay noise.

Additional factors that can influence titers include the specific assay platform used (different manufacturers may yield different absolute values), the timing of the blood draw relative to any intercurrent illness, and variations in sample handling. For these reasons, a single elevated or slightly changed IgG value should not be over-interpreted without clinical correlation.

6. The EBV Marker That Actually Matters for Reactivation

Many standard lab panels check EBV VCA IgG and EBNA IgG—both of which simply confirm past infection and remain positive for life. The marker that correlates most closely with chronic viral reactivation is EBV Early Antigen-Diffuse (EA-D) IgG. Elevated EA-D IgG suggests that the virus has recently entered its lytic (replicative) cycle, which is the phase associated with symptoms and tissue damage.

A more comprehensive EBV evaluation should include:

• EBV VCA IgM (acute or reactivation marker)
• EBV EA-D IgG (lytic reactivation marker)
• EBV PCR (quantitative) (direct viral DNA measurement)
• EBV EBNA IgG (confirms past infection; absence with positive VCA IgG may suggest chronic active infection)

If your provider is only tracking VCA IgG, you may be missing the markers that would actually tell you whether EBV is reactivating. Requesting an EA-D IgG and/or EBV PCR can provide much more clinically useful information.

7. Putting It All Together: Your Improvements Are Significant

The patient who prompted this discussion had achieved something remarkable: the lowest thyroid antibodies in their history and a first negative ANA in nearly two decades. These are not minor achievements—they represent measurable evidence that immune regulation is improving.

Stable EBV and CMV IgG titers in this context are not a sign that something is wrong. They are an immunologically predictable finding that reflects the normal biology of herpesvirus latency and long-lived plasma cell function. The autoimmune markers that improved are the ones LDN is designed to influence. The herpesvirus IgG markers that stayed the same are produced by a different arm of the immune system that LDN does not directly target.

Clinical Bottom Line

1. EBV and CMV IgG antibodies reflect immune memory, not active infection. They are produced by long-lived plasma cells that can persist for decades and are not expected to decline with LDN or antiviral therapy.
2. LDN modulates autoimmunity; it does not target latent herpesviruses. Improvements in TPO antibodies and ANA are expected LDN effects. Stable herpesvirus IgG is also expected.
3. Antivirals suppress lytic replication only. They cannot eliminate latent virus from memory B cells, and therefore do not reliably change IgG titers.
4. IgG titers can fluctuate due to assay variability. Changes of 20–40% may not be clinically meaningful.
5. If you suspect EBV reactivation, ask for EA-D IgG and/or EBV PCR. These are far more informative than VCA IgG for assessing active viral behavior.
6. Improving autoimmune markers while herpesvirus IgG remains stable is a clinical success, not a failure. Celebrate the wins.

References

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Yoon Hang Kim, MD, MPH | Direct Integrative Care

www.DirectIntegrativeCare.com | LDN Support Group