Assay Detects Interferon Antibodies, Drug Bioactivity in Hepatitis C Patients

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Assay Detects Interferon Antibodies, Drug Bioactivity in Hepatitis C

Patients

NEW YORK (Reuters Health) Jan 06 - German researchers have developed

a new screening system to identify interferon-neutralizing antibodies

in patients with hepatitis C who are not responding to interferon

alpha therapy.

The assay includes a real-time RT-PCR test that identifies MxA

expression in peripheral blood mononuclear cells. MxA is a GTPase

induced by interferon that is a " highly specific and reliable " marker

for the drug's bioactivity, Dr. Georg Kochs of the Institute for

Medical Microbiology and Hygiene in Freiburg and colleagues write in

the January issue of the Journal of Medical Virology.

Dr. Kochs and his team used the assay to identify interferon alpha-

neutralizing antibodies in sera from 3 of 38 patients not responding

to interferon, but did not find the antibodies in 24 patients with

hepatitis C who responded to interferon therapy or in 21 healthy

controls.

The researchers also found a correlation between presence of the

antibodies and a lack of MxA induction after interferon treatment,

indicating a " complete lack of IFN bioactivity. "

The role of anti-interferon antibodies in interferon resistance to

hepatitis C " is still a matter of debate, " the researchers

note. " This new and convenient bioassay constitutes a helpful tool

for answering this important question. "

The test, based on a reporter plasmid containing the luciferase gene

controlled by the Mx1 promoter, does not require special bioassay

conditions, and is both convenient and sensitive, the researchers

note. They suggest that it could be used to identify patients who are

not responding to interferon early in therapy and monitor them for

the development of interferon-neutralizing antibodies.

" The data obtained should be used to optimize further treatment and

possibly to identify alternative interferon preparations not

neutralized by the patient's serum, " the researchers conclude.

J Med Virol 2005;78:74-82.