scholarly journals Infectivity variation and genetic diversity among strains of Western equine encephalitis virus

2006 ◽  
Vol 87 (8) ◽  
pp. 2353-2361 ◽  
Author(s):  
Les P. Nagata ◽  
Wei-Gang Hu ◽  
Michael Parker ◽  
Damon Chau ◽  
George A. Rayner ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Amino Acid ◽  
Amino Acid Identity ◽  
Encephalitis Virus ◽  
Structural Proteins ◽  
Structural Protein ◽  
Time To Death ◽  
Equine Encephalitis Virus ◽  
Western Equine Encephalitis Virus ◽  
Western Equine Encephalitis

Variation in infectivity and genetic diversity in the structural proteins were compared among eight strains of Western equine encephalitis virus (WEEV) to investigate WEEV virulence at the molecular level. A lethal intranasal infectivity model of WEEV was developed in adult BALB/c mice. All eight strains examined were 100 % lethal to adult mice in this model, but they varied considerably in the time to death. Based on the time to death, the eight strains could be classified into two pathotypes: a high-virulence pathotype, consisting of strains California, Fleming and McMillan, and a low-virulence pathotype, comprising strains CBA87, Mn548, B11, Mn520 and 71V-1658. To analyse genetic diversity in the structural protein genes, 26S RNAs from these eight strains were cloned and sequenced and found to have >96 % nucleotide and amino acid identity. A cluster diagram divided the eight WEEV strains into two genotypes that matched the pathotype grouping exactly, suggesting that variation in infectivity can be attributed to genetic diversity in the structural proteins among these eight strains. Furthermore, potential amino acid differences in some positions between the two groups were identified, suggesting that these amino acid variations contributed to the observed differences in virulence.

scholarly journals Identification of Western Equine Encephalitis Virus Structural Proteins That Confer Protection after DNA Vaccination

2009 ◽  
Vol 17 (1) ◽  
pp. 176-179 ◽  
Author(s):  
Penelope J. Gauci ◽  
Josh Q. H. Wu ◽  
George A. Rayner ◽  
Nicole D. Barabé ◽  
Leslie P. Nagata ◽  
...  
Keyword(s):  
Mouse Model ◽  
Dna Vaccination ◽  
Encephalitis Virus ◽  
Structural Proteins ◽  
Structural Protein ◽  
Complete Protection ◽  
Equine Encephalitis Virus ◽  
Homologous Strain ◽  
Western Equine Encephalitis Virus ◽  
Western Equine Encephalitis

ABSTRACT DNA vaccines encoding different portions of the structural proteins of western equine encephalitis virus were tested for the efficacy of their protection in a 100% lethal mouse model of the virus. The 6K-E1 structural protein encoded by the DNA vaccine conferred complete protection against challenge with the homologous strain and limited protection against challenge with a heterologous strain.

scholarly journals Virulence variation among isolates of western equine encephalitis virus in an outbred mouse model

2009 ◽  
Vol 90 (8) ◽  
pp. 1848-1858 ◽  
Author(s):  
Christopher H. Logue ◽  
Christopher F. Bosio ◽  
Thomas Welte ◽  
Kimberley M. Keene ◽  
Jeremy P. Ledermann ◽  
...  
Keyword(s):  
Mouse Model ◽  
Genome Sequence ◽  
Cultured Cells ◽  
Distribution Patterns ◽  
Encephalitis Virus ◽  
Full Genome Sequence ◽  
Time To Death ◽  
Equine Encephalitis Virus ◽  
Western Equine Encephalitis Virus ◽  
Western Equine Encephalitis

Little is known about viral determinants of virulence associated with western equine encephalitis virus (WEEV). Here, we have analysed six North American WEEV isolates in an outbred CD1 mouse model. Full genome sequence analyses showed ≤2.7 % divergence among the six WEEV isolates. However, the percentage mortality and mean time to death (MTD) varied significantly when mice received subcutaneous injections of 103 p.f.u. of each virus. Two WEEV strains, McMillan (McM) and Imperial 181 (IMP), were the most divergent of the six in genome sequence; McM caused 100 % mortality by 5 days post-infection, whereas IMP caused no mortality. McM had significantly higher titres in the brain than IMP. Similar differences in virulence were observed when McM and IMP were administered by aerosol, intranasal or intravenous routes. McM was 100 % lethal with an MTD of 1.9 days when 103 p.f.u. of each virus was administered by intracerebral inoculation; in contrast, IMP caused no mortality. The presence of IMP in the brains after infection by different routes and the lack of observed mortality confirmed that IMP is neuroinvasive but not neurovirulent. Based on morbidity, mortality, MTD, severity of brain lesions, virus distribution patterns, routes of infection and differences in infection of cultured cells, McM and IMP were identified as high- and low-virulence isolates, respectively.

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