Genetic characteristics of field and attenuated rabies viruses ... - Evira

Nadin-Davis et al., 2001, 2003; Favoretto et al., 2002).
Most of the rabies cases in terrestrial animals and human beings are due to the
genotype 1 viruses, but some cases are caused by viruses from other genotypes. Spillover
of the EBLV1 virus into the stone marten (Martes foina) under natural conditions has
been recorded in Germany (Muller et al., 2004). Also in 1998 cases of rabies in sheep
that were shown to have been infected with the EBLV-1a possibly derived from
insectivorous bats were observed in Denmark (Stougaard and Ammendrup, 1998), and in
2002, a second occurrence of the EBLV-type 1 in sheep was reported (Ronsholt, 2002).
Also, several human cases caused by EBLVs and ABLV strains have been reported in
some European countries and in Australia (Lumio et al., 1986; McColl et al., 2000; Fooks
et al., 2003; Spooner, 2003).
One of the most important issues in the field of rabies research is the identification
and characterization of new genotypes. Due to PCR and nucleotide sequencing during
the last ten years, one new genotype has been identified and four additional were
proposed. Fraser et al. (1996) isolated a new Lyssavirus from bats in Australia, which was
later identified by nucleotide sequencing as the new seventh genotype: Australian bat
Lyssavirus or ABLV (Gould et al., 1998). The phylogenetic analysis of the ABLV viruses
has shown that they form a monophyletic group distinct from the other Lyssaviruses, and
two antigenic variants of ABLV were described (Guyatt et al., 2003). Arai et al., (2003)
studied rabies virus isolated from the Lesser Mouse-eared Bat (Myotis blythi) in
Kyrgyzstan and have suggested that it belonged to a new genotype of the rabies virus
(Aravan virus). Furthermore, the Khujand virus isolated from northern Tajikistan in 2001
can be classified as a separate genotype of Lyssavirus (Kuzmin et al., 2003). Two unique
viruses (Irkut and West Caucasian) have been isolated from bats in Russia and based on
genetic studies it has been suggested that they belong to new genotypes (Botvinkin et al.,
2003; Kuzmin et al., 2005).
1.7.3. Entire genome sequencing of vaccine strains
The entire genome sequencing of the vaccine strains provides important data
relative to the rabies virus genome and allows its antigenic, genetic, and immunogenic
properties to be predicted and analyzed. To conduct complete sequencing of the rabies
virus genome, several techniques can be employed. Tordo et al. (1986, 1988) used
cloning in plasmid vector pBR322 and sequence determination by the chain-terminating
inhibitor method after inserting endonuclease restriction fragments of the cDNA inserts
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