Culex Tarsalis Mosquitoes as Vectors of Highlands J Virus.

The research article explores how the Culex Tarsalis mosquito can transmit the Highlands J virus (HJV). The article reveals that different strains of the virus exhibit varying infection rates and shed light on possible transmission patterns in the western United States.

Introduction to HJV and Related Research

• The research revolves around the Highlands J virus (HJV), an avian pathogen associated primarily with birds and does not cause diseases in humans or equines.
• The virus is predominantly found in the eastern United States but its behavior is not entirely understood.
• The paper seeks to determine if the virus may be transmitted by the Culex species mosquitoes, in similarity to Western equine encephalitis virus (WEEV), a virus with which it shares a genetic similarity.
• To investigate this, seven strains of HJV were examined to evaluate the possibility of transmission via Culex tarsalis mosquitoes.

Strains and Infection Rates

• The research identified four distinct lineages of the HJV virus, referred to as lineages 1-4, through a comprehensive analysis of the complete sequences of the virus’s genome.
• Interestingly, the different lineages were found to have varying infection rates. It was identified that lineage 1 strains of the virus exhibited low infection rates, while lineages 2 and 4 demonstrated significantly higher infection rates. These higher rates were comparable to those recorded for the Western equine encephalitis virus (WEEV).

Mosquito Body Viral Titers

• The team also measured average mosquito body viral titers, which were found to be at their peak at 8 days post-infection (dpi).
• It was observed that nearly 45% of mosquitoes which had been infected with strain AB-80-9 virus were able to transmit the virus through their saliva, with its titer at an average of 5.02 log10 pfu equivalents/saliva.

Role of Single Amino Acid

• An intriguing finding in the study was the identification of a single amino acid difference between the strains with high and low infectivity rates.
• This difference was observed at genome position 8605, in the E2 gene of the virus. A nonpolar glycine was present in the low-infectivity lineage 1 strains, while an acidic glutamic acid was present in the higher infectivity lineage 2 and 4 strains.

Implication of Findings

• This research asserts the ability of Cx. tarsalis mosquitoes to carry and transmit the HJV virus, thereby indicating the possibility of transmission in the western United States, an area where this specific mosquito species is prevalent.
• The study also highlights the necessity of further research to understand the transmission patterns of the Culex species, underlining the connection between the virus and its vector.