Institute for Animal Health, Pirbright Laboratory, Ash Road Pirbright Surrey GU24 0NF, UK.
Abstracts of the papers presented at the International Conference of Indian Virological Society on “Emerging and Re-emerging viral Diseases of the Tropics and Subtropics” at Indian Agricultural Research Institute, New Delhi, India, December 11–14, 2007.
The development of reverse genetics for morbilliviruses has greatly advanced our knowledge of the biology of this virus group. The technology, which allows efficient site-specific mutagenesis of genes, has enabled us to study the molecular factors that govern host range and to identify specific sequences motifs essential for replication. Sequence analysis of different virus strains has, in combination with reverse genetics, enabled us to identify regions in the promoters which are essential for replication and others which when changed can affect virus virulence but not replication in cell culture. In addition, the ability to express foreign genes in recombinant viruses allows us to establish the effects these foreign genes have on virus growth in vivo and in vitro. This can also be a means of adding genetic markers to the virus vaccines which will subsequently allow vaccinated animals to be identified and distinguished from naturally infected ones. In this presentation I will describe work with rinderpest virus which has enabled us to identify changes that are common to vaccines strains of rinderpest and peste des petits ruminants (PPR) viruses which if altered have the ability to attenuate the virus in vivo. Other work with GFP labelled viruses has shown that the effects of insertion of the GFP coding sequence vary, depending on the positioning of the GFP coding sequence in the virus genome. This provides both the means to study virus replication by live cell imaging using confocal microscopy and to follow the spread of the virus in the tissues and organs of an infected animal.
