Two novel genetic groups (VIIb and VIII) responsible for recent Newcastle disease outbreaks in Southern Africa, one (VIIb) of which reached Southern Europe
J. Herczeg et al., Two novel genetic groups (VIIb and VIII) responsible for recent Newcastle disease outbreaks in Southern Africa, one (VIIb) of which reached Southern Europe, ARCH VIROL, 144(11), 1999, pp. 2087-2099
34 strains of Newcastle disease virus (NDV) isolated during epizootics in t
he Republic of South Africa and in Mozambique between 1990 and 1995, and in
Bulgaria and Turkey in 1995-1997 were identified by restriction enzyme and
partial sequence analysis of the fusion (F) protein gene. The majority of
isolates in southern Africa and those from Bulgaria and Turkey were placed
into a novel group which has been termed VIIb. Group VIIb is part of a larg
er genetic cluster (VII) that also includes NDV strains from the Far East a
nd some western European countries (VIIa). The genetic distance of 7-8, 5 %
between genotype VIIa and VIIb viruses excludes the existence of a direct
epidemiological link between recent southern African epizootics and outbrea
ks in either western Europe in the 1990's or those of the Far East. Another
hitherto unrecorded genotype (VIII) was also found in South Africa with de
scendants of putative ancestral members isolated in the 1960's. The genetic
distance of recent group VIII strains from the major epizootic genotype (V
IIb) is over 11%, therefore outbreaks caused by them were epidemiologically
unrelated. Genotype VIII viruses must have been maintained in South Africa
by endemic infections during the past decades while group VIIb appears to
be introduced more recently.