Hepatitis B is one of the major public health problems worldwide since approximately 350 million, i.e. 5% of the total population, are infected chronically [
1]. An important way to prevent infections encompasses disinfection measures to interrupt transmission by the inactivation of the virus on instruments, surfaces and in biological materials [
2]. The hepatitis B virus (HBV) can be inactivated effectively inter alia by chemical biocides characterized by broad-spectrum virucidal activity according to the norm EN 14476:2007 [
3]. However, the number of agents achieving broad-spectrum virucidal efficacy is limited and they are not required for the inactivation of HBV such as other human blood-borne viruses since these lipophilic viruses with an envelope are characterized by lower stability than viruses without envelope [
4]. Thus, a German guideline for testing the virucidal activity of chemical disinfectants in the human medical area [
5] differentiates between disinfectants with virucidal activity effective against non-enveloped plus enveloped viruses and disinfectants with limited virucidal activity exclusively effective against enveloped viruses. Limited virucidal activity has been declared when there is a proven efficacy against two representatives of enveloped viruses, the vaccinia virus strain Lister Elstree (VACV) or the modified vaccinia Ankara strain (MVA) [
6] and the bovine viral diarrhea virus (BVDV) strain NADL. Even though biocides with limited virucidal activity can be assumed to be effective against HBV, an efficacy cannot be predicted reliably and, therefore, the virucidal efficacy against HBV has to be validated by the use of robust laboratory methods.
So far, the virucidal efficacy of biocides against HBV can be stringently determined only
in vivo by chimpanzee infection assays [
7] with less sensitivity or by the use of primary hepatocyte cultures derived from Tupaias, small-squirrel-like animals living in Southeast Asia [
8]. However, while animal protection and economic reasons prohibit the use of higher primates for routine tests on commercial products, the Tupaia model is expensive, the availability of hepatocytes is limited and the test requires human sera with high viral load. Furthermore, surrogate assays for measuring integrity of viral DNA [
9], activity of viral DNA polymerase [
10], reactivity of HBV surface antigen [
11] and the physical integrity of infectious viral particles [
12] do not correlate reliably with the infectivity of HBV. In addition, the use of the hepatoma cell line HepG2 [
13] is very doubtful. However, redifferentiated Hepa RG cells [
14] are well accepted and reproducible as HBV infectivity system, but they have not been applied for testing the hepatitis B virucidal activity of biocides. Thus, the most promising and feasible assay is at present the use of a taxonomically related surrogate virus of the same virus family
Hepadnaviridae, namely, the duck hepatitis B virus (DHBV), which can be propagated in ducklings or in primary duck embryonic hepatocytes [
15,
16]. Duck hepatitis B virus shares many physical properties with the closely related HBV [
17] and similar inactivation kinetics by disinfectants compared with chimpanzee transmission studies of HBV have been reported [
7]. In Germany, the infection of primary duck embryonic hepatocytes with DHBV was established and evaluated for virucidal testing in several studies [
18‐
20].
The objective of the present study was to compare the limited virucidal activity of different biocides, which are often used as ingredients in disinfectants, against DHBV and VACV/MVA. The results should provide information whether the virucidal activity of biocides against VACV/MVA, the most important model viruses for the determination of limited virucidal activity, includes the inactivation of DHBV.