Detection of human herpesvirus-6 in cerebrospinal fluid of patients with encephalitis
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Karen Yao1, Somayeh Honarmand, Alex Espinosa
1Viral Immunology Section, Neuroimmunology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
Objective:
Virus infections are the most common causes of encephalitis, a syndrome characterized by acute inflammation of the brain. More than 150 different viruses have been implicated in the pathogenesis of encephalitis; however, because of limitations with diagnostic testing, causative factors of more than half of the cases remain unknown.
Methods:
To investigate whether human herpesvirus-6 (HHV-6) is a causative agent of encephalitis, we examined for evidence of virus infection by determining the presence of viral sequence using polymerase chain reaction and assessed HHV-6 antibody reactivity in the cerebrospinal fluid of encephalitis patients with unknown cause. In a cohort study, we compared virus-specific antibody levels in cerebrospinal fluid samples of patients with encephalitis, relapsing-remitting multiple sclerosis, and other neurological diseases.
Results:
Our results demonstrated increased levels of HHV-6 IgG, as well as IgM levels, in a subset of encephalitis patients compared with other neurological diseases. Moreover, cell-free viral DNA that is indicative of active infection was detected in 40% (14/35) of encephalitis patients, whereas no amplifiable viral sequence was found in either relapsing-remitting MS or other neurological diseases patients. In addition, a significant correlation between polymerase chain reaction detection and anti-HHV-6 antibody response was also demonstrated.
Interpretation:
Collectively, these results suggested HHV-6 as a possible pathogen in a subset of encephalitis cases.
Insights
Human herpesvirus-6 (HHV-6) may cause encephalitis, a brain inflammation. Researchers found HHV-6 DNA and antibodies in some encephalitis patients, suggesting it as a potential pathogen.
Area of Science:
- Neurology
- Virology
- Infectious Diseases
Background:
- Virus infections are primary causes of encephalitis, leading to acute brain inflammation.
- The causative agents for over half of encephalitis cases remain unidentified due to diagnostic limitations.
Purpose of the Study:
- To investigate the role of human herpesvirus-6 (HHV-6) as a potential cause of encephalitis.
- To determine if HHV-6 is present in patients with unexplained encephalitis.
Main Methods:
- Examined cerebrospinal fluid (CSF) from encephalitis patients for HHV-6 DNA using polymerase chain reaction (PCR).
- Assessed HHV-6 specific antibody (IgG and IgM) levels in CSF.
- Compared findings with CSF samples from patients with multiple sclerosis and other neurological diseases.
Main Results:
- Elevated HHV-6 IgG and IgM antibodies were detected in a subset of encephalitis patients.
- Cell-free viral DNA, indicating active infection, was found in 40% of encephalitis patients.
- A significant correlation was observed between PCR detection of HHV-6 and the presence of anti-HHV-6 antibodies.
Conclusions:
- Human herpesvirus-6 (HHV-6) is suggested as a potential pathogen in some cases of encephalitis.
- These findings highlight the importance of considering HHV-6 in the differential diagnosis of encephalitis.
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