First evidence of West Nile virus lineage 2 circulation in Turkey.

The research article discusses the detection of a West Nile Virus (WNV) strain in Turkey, specifically in a horse in 2014. This event is significant as it marks the first-ever recorded incidence of WNV lineage 2 circulation in the country.

Summary of Findings

• The article opens with the disclosure of how West Nile virus (WNV), a typically lineage 1 disease, was discovered in lineage 2 form in Turkey in August 2014. The virus was identified in the brain tissues of a nine-year-old horse that was euthanised due to severe clinical signs of the disease.
• Phylogenetic analyses of a portion of the NS3 coding region of the virus revealed that this Turkish strain was similar to those isolated in Greece between 2010 and 2012. This points to possible commonalities in the strain types of the virus found in different geographical regions.
• The researchers also found WNV antibodies in other horses in the vicinity of the outbreak. Specifically, two horses carried both IgG and IgM type WNV antibodies while an additional 11 horses had only IgG type WNV antibodies. This appears to suggest an exposure to the virus within the horse population in that region.
• However, the study could not identify WNV RNA in a number of mosquitoes (Culex pipiens, Ochlerotatus caspius, and Culex theileri) collected from the infected premises. The absence of WNV RNA indicates that these mosquitoes were not carriers of the virus at the time of the study.

Implications and Significance

• The discovery of this WNV lineage 2 strain in Turkey highlighted a possible shift or expansion in the geographical range of this virus lineage. Typically, lineage 1 is predominant in the Western hemisphere, while lineage 2 was initially limited to sub-Saharan Africa but has been increasingly found in Europe in recent years.
• The detection of antibodies in other horses suggests that the virus might be circulating within the horse population. As WNV is zoonotic (transmissible from animals to humans), the implication for public health should be considered.
• The lack of detectable WNV RNA in the mosquito species sampled indicates that they were not actively transmitting the virus at the time of sampling. However, it does not rule out the possibility that they could be potential vectors of the disease in the right conditions.