Encephalitis Caused by Jamestown Canyon Virus in a Liver Transplant Patient, North Carolina, USA, 2017

Two Insects, Two Bites, One Patient: A Lyme Disease and Jamestown Canyon Co-infection

Lyme disease (LD) is the most common tick-borne illness across the United States, caused by the bacterium Borrelia burgdorferi sensu lato and transmitted to humans by the bite of infected Ixodes ticks. Jamestown Canyon Virus (JCV) is an emerging mosquito-borne pathogen found mostly in the upper Midwest and Northeastern United States. Co-infection between these two pathogens has not been previously reported since it would require the host to be bitten by the two infected vectors at the same time. We report a 36-year-old man who presented with erythema migrans and meningitis. While erythema migrans is a pathognomonic sign of early localized Lyme disease, Lyme meningitis does not occur in this stage but in the early disseminated stage. Furthermore, CSF tests were not supportive of neuroborreliosis, and the patient was ultimately diagnosed with JCV meningitis. We review JCV infection, LD, and this first reported co-infection to illustrate the complex interaction between different vectors and pathogens and to emphasize the importance of considering co-infection in people who live in vector-endemic areas.

Structure, function, and evolution of the Orthobunyavirus membrane fusion glycoprotein

La Crosse virus, responsible for pediatric encephalitis in the United States, and Schmallenberg virus, a highly teratogenic veterinary virus in Europe, belong to the large Orthobunyavirus genus of zoonotic arthropod-borne pathogens distributed worldwide. Viruses in this under-studied genus cause CNS infections or fever with debilitating arthralgia/myalgia syndromes, with no effective treatment. The main surface antigen, glycoprotein Gc (∼1,000 residues), has a variable N-terminal half (Gc^S) targeted by the patients' antibody response and a conserved C-terminal moiety (Gc^F) responsible for membrane fusion during cell entry. Here, we report the X-ray structure of post-fusion La Crosse and Schmallenberg virus Gc^F, revealing the molecular determinants for hairpin formation and trimerization required to drive membrane fusion. We further experimentally confirm the role of residues in the fusion loops and in a vestigial endoplasmic reticulum (ER) translocation sequence at the Gc^S-Gc^F junction. The resulting knowledge provides essential molecular underpinnings for future development of potential therapeutic treatments and vaccines.

Vector competence of Anopheles quadrimaculatus and Aedes albopictus for genetically distinct Jamestown Canyon virus strains circulating in the Northeast United States

BACKGROUND

Jamestown Canyon virus (JCV; Peribunyaviridae, Orthobunyavirus) is a mosquito-borne pathogen belonging to the California serogroup. The virus is endemic in North America and increasingly recognized as a public health concern. In this study, we determined the vector competence of Anopheles (An.) quadrimaculatus and Aedes (Ae.) albopictus for five JCV strains belonging to the two lineages circulating in the Northeast.

METHODS

An. quadrimaculatus and Ae. albopictus were fed blood meals containing two lineage A strains and three lineage B strains. Vector competence of both mosquito species was evaluated at 7- and 14-days post-feeding (dpf) by testing for virus presence in bodies, legs, and saliva.

RESULTS

Our results demonstrated that Ae. albopictus mosquitoes are a competent vector for both lineages, with similar transmission levels for all strains tested. Variable levels of infection (46-83%) and dissemination (17-38%) were measured in An. quadrimaculatus, yet no transmission was detected for the five JCV strains evaluated.

CONCLUSIONS

Our results demonstrate that establishment of Ae. albopictus in the Northeast could increase the risk of JCV but suggest An. quadrimaculatus are not a competent vector for JCV.