Relapsing-remitting multiple sclerosis and human herpesvirus 6 active infection.
BACKGROUND
Recent studies have focused on the relationship between human herpesvirus 6 (HHV-6) and multiple sclerosis (MS).


OBJECTIVE
To analyze HHV-6 messenger RNA expression in patients with relapsing-remitting (RR) MS vs healthy blood donors (HBDs).


METHODS
One hundred fifty-four subjects were enrolled in the study: 105 patients with RRMS (32 in relapse) and 49 HBDs. Total DNA and messenger RNA were extracted from serum and blood samples, respectively, and analyzed by quantitative real-time reverse transcription-polymerase chain reaction for the detection of 3 HHV-6 immediate-early genes (U16/U17,U89/U90, and U94) and both HHV-6 variants (HHV-6A and HHV-6B).


RESULTS
Active HHV-6 infection was detected in 16% of patients with RRMS vs 0% of HBDs (P = .003). Seven patients with RRMS with exacerbation had HHV-6 active replication, and the virus remained latent in only 1 of them. We did not find any statistically significant difference between HHV-6 active or latent infection for patients in remission (P = .12). Among patients with RRMS with HHV-6 active replication, viral load was higher when they experienced an acute attack than when in remission (P = .04). In those patients with RRMS who had an active infection only, HHV-6A was found. Cell-free HHV-6 DNA detected in serum samples confirmed the results.


CONCLUSIONS
The results show that a subset of patients with RRMS experience HHV-6 active infection, and there likely is an association between the viral active replication and relapses; therefore, HHV-6 active infection may imply a greater risk of exacerbations in a subgroup of patients with RRMS.
Alvarez-Lafuente
Roberto
R
Servicio de Neurología, Hospital Clínico San Carlos, 28040 Madrid, Spain. labesmul@hcsc.es
De las Heras
Virginia
V
Bartolomé
Manuel
M
Picazo
Juan José
JJ
Arroyo
Rafael
R
D000328:Adult; D004279:DNA, Viral / Q000097:blood; D005260:Female; D006566:Herpesviridae Infections / Q000097:blood / Q000150:complications / Q000821:virology*; D015654:Herpesvirus 6, Human / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D008297:Male; D008875:Middle Aged; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000097:blood / Q000150:complications / Q000821:virology*; D012333:RNA, Messenger / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D019562:Viral Load / Q000706:statistics & numerical data
D004279:DNA, Viral; D012333:RNA, Messenger