Arch Virol (2002) 147: 659–663
Importance of thymidine kinase activity for normal growth
of lumpy skin disease virus (SA-Neethling)
D. B. Wallace and G. J. Viljoen
Applied BiotechnologyDivision, Onderstepoort VeterinaryInstitute,
Pretoria, South Africa
Accepted July10, 2001
Summary. In order to studythe importance of an intact thymidine kinase (TK)
gene for the vaccine strain of a southern African capripoxvirus, namely, lumpy
skin disease virus (LSDV) (type SA-Neethling), a TK disruption recombinant
was generated expressing the Escherichia coli
-galactosidase (lacZ) reporter
gene. A comparative growth studyof the recombinant and wild-type (wt) LSDV
in TK-positive primaryand secondarycells and TK-negative secondarycells was
performed. It was found that although recombinant and wt virus both grew in
TK-positive cells without selection, the recombinant was unable to grow in TK-
negative cells (with or without selection), indicating that TK activityis important,
if not essential, for normal growth of LSDV.
Poxviruses have been extensivelyinvestigated for their potential use as vectors in
recombinant vaccine production [1, 3, 5, 6, 12, 16, 17]. Vaccinia virus, belonging
to the Orthopoxvirus genus, was the ﬁrst poxvirus used to generate recombinants
with insertion of foreign genes into the viral thymidine kinase (TK) gene [7, 16].
This was made possible since the TK gene was found to be non-essential for the
normal growth of the virus.
Due to their narrow host-range speciﬁcity, members of the Capripoxvirus
genus are being targeted as vectors for recombinant vaccines . The genus
virus (LSDV) (of cattle) .
A recombinant capripoxvirus from a north African isolate, KS-1, express-
ing the fusion gene of rinderpest virus was shown to protect cattle against both
rinderpest and lumpyskin disease (LSD) . In southern Africa onlyone
capripoxvirus, namelyLSDV (type SA-Neethling), is known to occur.We are