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Updated: Jul 15, 2026
Arbovirus Infections As Screening Tools for the Identification of Viral Immunomodulators and Host Antiviral Factors
Published on: September 13, 2018
Genome sequence analysis of La Crosse virus and in vitro and in vivo phenotypes
Richard S Bennett1, David R Ton, Christopher T Hanson
1Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA. bennettri@niaid.nih.gov
Background:
La Crosse virus (LACV), family Bunyaviridae, is a mosquito-borne virus recognized as a major cause of pediatric encephalitis in North America with 70-130 symptomatic cases each year. The virus was first identified as a human pathogen in 1960 after its isolation from a 4 year-old girl who suffered encephalitis and died in La Crosse, Wisconsin. The majority of LACV infections are mild and never reported, however, serologic studies estimate infection rates of 10-30/100,000 in endemic areas.
Results:
In the present study, sequence analysis of the complete LACV genomes of low-passage LACV/human/1960, LACV/mosquito/1978, and LACV/human/1978 strains and of biologically cloned derivatives of each strain, indicates that circulating LACVs are genetically stable over time and geographic distance with 99.6-100%, 98.9-100%, 97.8-99.6%, and 99.2-99.7% amino acid identity for N, NsS, M polyprotein, and L proteins respectively. We identified 5 amino acid differences in the RNA polymerase and 4 nucleotide differences in the non-coding region of the L segment specific to the human virus isolates, which may result in altered disease outcomes.
Conclusion:
All three wild type viruses had similar in vitro growth kinetics and phenotypes in mosquito C6/36 and Vero cells, and similar levels of neurovirulence and neuroinvasiveness in Swiss Webster mice. The biologically cloned derivative of LACV/human/1960 was significantly less neuroinvasive than its uncloned parent and differed in sequence at one amino acid position in the GN glycoprotein, identifying this residue as an attenuating mutation.
