Y. Ito et al., Detection of influenza virus RNA by reverse transcription-PCR and proinflammatory cytokines in influenza-virus-associated encephalopathy, J MED VIROL, 58(4), 1999, pp. 420-425
Eleven children with acute encephalopathy associated with an influenza viru
s infection were treated during the 1997-1998 influenza season. Reverse tra
nscription-polymerase chain reaction (RT-PCR) assay was used to detect the
viral genome in peripheral blood and cerebrospinal fluid (CSF) samples. The
results were compared with those of control influenza patients without neu
rological complications. Viral RNA was detected only in the peripheral bloo
d mononuclear cells of one patient with influenza-virus-associated encephal
opathy (1 of 9; 11%) and in the CSF of another patient (1 of 11; 9%). RT-PC
R was negative in the blood of all the controls, but the percentage of RT-P
CR-positive samples in the two groups was not significantly different. Cyto
kines and soluble cytokine receptors in plasma and CSF were then quantified
using an enzyme-linked immunosorbent assay. The CSF concentrations of solu
ble tumor necrosis factor receptor-1 were elevated in two patients and inte
rleukin-6 (IL-6) was elevated in one patient with influenza-virus-associate
d encephalopathy. On the other hand, the plasma concentrations of IL-6 were
elevated in four of nine patients. The number of encephalopathy patients w
ho had elevated plasma concentrations of IL-6 100 pg/ml was significantly h
igher than that of controls (P = .01). In conclusion, the infrequent detect
ion of the viral genome in the CSF and blood showed that direct invasion of
the virus into the central nervous system was an uncommon event. Proinflam
matory cytokines and soluble cytokine receptors may mediate the disease. Th
e high plasma concentration of IL-6 could be an indicator of the progressio
n to encephalopathy. J. Med. Virol. 58:420-425, 1999. (C) 1999 Wiley-Liss,
Inc.