West Nile virus: an overview of its spread in Europe and the Mediterranean basin in contrast to its spread in the Americas

Novel flavivirus or new lineage of West Nile virus, central Europe

Rabensburg virus, isolated from Culex pipiens mosquitoes in central Europe, represents a new lineage of West Nile virus or a novel flavivirus of the Japanese encephalitis virus group.

A flavivirus (strain 97-103) was isolated from Culex pipens mosquitoes in 1997 following floods in South Moravia, Czech Republic. The strain exhibited close antigenic relationship to West Nile virus (WNV) prototype strain Eg-101 in a cross-neutralization test. In this study, mouse pathogenicity characteristics and the complete nucleotide and putative amino acid sequences of isolate 97-103, named Rabensburg virus (RabV) after a nearby Austrian city, were determined. RabV shares only 75%–77% nucleotide identity and 89%–90% amino acid identity with representative strains of WNV lineages 1 and 2. Another RabV strain (99-222) was isolated in the same location 2 years later; it showed >99% nucleotide identity to strain 97-103. Phylogenetic analyses of RabV, WNV strains, and other members of the Japanese encephalitis virus (JEV) complex clearly demonstrated that RabV is either a new (third) lineage of WNV or a novel flavivirus of the JEV group.

Sindbis viruses and other alphaviruses as cause of human arthritic disease

Amongst the arthritis-causing arboviruses, i.e. those spread by insects, the alphavirus group is of special interest. These viruses occasionally cause vast outbreaks, such as O'nyong-nyong in Africa in 1959. In Fennoscandia, Sindbis-related Ockelbo, Pogosta, or Karelian fever viruses have been found to cause significant morbidity. The major symptoms in addition to joint inflammation are fever, fatigue, headache and rash. The joint symptoms may persist for weeks, even months. The diagnosis is based on the clinical picture and serology. The causative viruses are closely related but not identical. It appears that at least in Finland the Pogosta disease is more common than thought, and the symptoms may often be overlooked. Several factors related to the viruses, their hosts, and global environmental changes may affect the spread of these viruses. All over the world arbovirus-caused diseases have increased, because of global changes.

Solution Structure and Antibody Binding Studies of the Envelope Protein Domain III from the New York Strain of West Nile Virus

The solution structure of domain III from the New York West Nile virus strain 385-99 (WN-rED3) has been determined by NMR methods. The West Nile domain III structure is a beta-barrel structure formed from seven anti-parallel beta-strands in two beta-sheets. One anti-parallel beta-sheet consists of beta-strands beta1 (Phe(299)-Asp(307)), beta2 (Val(313)-Tyr(319)), beta4 (Arg(354)-Leu(355)), and beta5 (Lys(370)-Glu(376)) arranged so that beta2 is flanked on either side by beta1 and beta5. The short beta4 flanks the end of the remaining side of beta5. The remaining anti-parallel beta-sheet is formed from strands beta3 (Ile(340)-Val(343)), beta6 (Gly(380)-Arg(388)), and beta7 (Gln(391)-Lys(399)) arranged with beta6 at the center. Residues implicated in antigenic differences between different West Nile virus strains (and other flaviviruses) and neutralization are located on the outer surface of the protein. Characterization of the binding of monoclonal antibodies to WN-rED3 mutants, which were identified through neutralization escape experiments, indicate that antibody neutralization directly correlates with binding affinities. These studies provide an insight into theoretical virus-receptor interaction points, structure of immunogenic determinants, and potential targets for antiviral agents against West Nile virus and highlight differences between West Nile virus and other flavivirus structures that may represent critical determinants of virulence.