Parvovirus B19 (B19V) can cause inflammatory
cardiomyopathy and endothelial dysfunction. Pathophysiological mechanisms involved include
lysophosphatidylcholine producing
phospholipase A2 (PLA2) activity of the B19V
capsid protein VP1. Most recently, VP1 and
lysophosphatidylcholine have been shown to inhibit Na(+)/K(+)
ATPase. The present study explored whether VP1 modifies the activity of Kv1.3 and Kv1.5 K(+) channels.
cRNA encoding Kv1.3 or Kv1.5 was injected into Xenopus oocytes without or with
cRNA encoding VP1 isolated from a patient suffering from fatal B19V-induced
myocarditis. K(+) channel activity was determined by dual
electrode voltage clamp. Injection of
cRNA encoding Kv1.3 or Kv1.5 into Xenopus oocytes was followed by appearance of Kv K(+) channel activity, which was significantly decreased by additional injection of
cRNA encoding VP1, but not by additional injection of
cRNA encoding PLA2-negative VP1 mutant (H153A). The effect of VP1 on Kv current was not significantly modified by transcription inhibitor
actinomycin (10 μM for 36 h) but was mimicked by
lysophosphatidylcholine (1 μg/ml). The B19V
capsid protein VP1 inhibits host cell Kv channels, an effect at least partially due to
phospholipase A2 (PLA) dependent formation of
lysophosphatidylcholine.