Passive immunization with anti-ActA and anti-listeriolysin O antibodies protects against Listeria monocytogenes infection in mice Original paper
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Divine Aleru
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Divine Aleru
Read MoreI am a biochemist with a deep curiosity for the human microbiome and how it shapes human health, and I enjoy making microbiome science more accessible through research and writing. With 2 years experience in microbiome research, I have curated microbiome studies, analyzed microbial signatures, and now focus on interventions as a Microbiome Signatures and Interventions Research Coordinator.
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Microbes
Microbes
Microbes are microscopic organisms living in and on the human body, shaping health through digestion, vitamin production, and immune protection. When microbial balance is disrupted, disease can occur. This guide explains key microbe types—bacteria, viruses, fungi, protozoa, and archaea—plus major pathogenic and beneficial examples.
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Divine Aleru
Read More
Researched by:
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Divine Aleru
ID
Divine Aleru
Read More
Microbiome Signatures identifies and validates condition-specific microbiome shifts and interventions to accelerate clinical translation. Our multidisciplinary team supports clinicians, researchers, and innovators in turning microbiome science into actionable medicine.
Divine Aleru
What was studied?
This study investigated the effects of passive immunization with antibodies targeting two virulence factors of Listeria monocytogenes, ActA and listeriolysin O (LLO), to assess their potential in protecting against listerial infection in mice. The study specifically examined how these antibodies neutralize bacterial activities and reduce infection severity.
Who was studied?
The study focused on Listeria monocytogenes, its virulence factors (ActA and LLO), and their interactions with immune responses in C57BL/6 mice, including IFN-γ−/− and TNF-α−/− knockout mice. The immune responses were evaluated using passive immunization with antibodies produced against ActA and LLO in rabbits.
What were the most important findings?
The study found that passive immunization with antibodies targeting ActA and LLO significantly protected mice from Listeria monocytogenes infection. Survival rates in antibody-treated mice were substantially improved compared to controls, especially when both anti-ActA and anti-LLO antibodies were used in combination. These antibodies reduced bacterial load in organs such as the spleen and liver, indicating that they inhibited bacterial growth and dissemination. The study also found that the protective effect was partially dependent on the presence of immune factors like IFN-γ and TNF-α. Additionally, anti-LLO antibodies were shown to neutralize LLO activity, reducing bacterial escape from lysosomes, while anti-ActA antibodies inhibited actin tail formation and cell-to-cell spread, further limiting bacterial dissemination. The antibodies did not significantly affect bacterial adhesion but played a critical role in reducing intracellular bacterial numbers.
What are the greatest implications of this study?
The findings of this study suggest that passive immunization with specific antibodies against ActA and LLO could serve as a promising therapeutic strategy for preventing or mitigating Listeria monocytogenes infections, especially in immunocompromised individuals or pregnant women who are most vulnerable to listeriosis. The ability of these antibodies to reduce bacterial spread and intracellular growth could be pivotal in managing severe infections. Furthermore, this study underscores the importance of targeting bacterial virulence factors, such as ActA and LLO, which play critical roles in immune evasion and intracellular survival. The approach of using antibodies to neutralize bacterial toxins and inhibit cell-to-cell spread could be applied not only to Listeria but also to other intracellular pathogens.
Listeria monocytogenes
Listeria monocytogenes is an opportunistic pathogen capable of surviving in diverse environments, including soil, water, and decaying vegetation. L. monocytogenes has the unique ability to evade the immune system by moving directly from cell to cell within the host. This intracellular lifestyle allows the bacterium to avoid extracellular immune detection, contributing to its ability to cause invasive diseases like meningitis and septicemia, particularly in the elderly and immunocompromised.