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Researchers from the University of Connecticut (UConn) have successfully determined the complete protein-coding sequences of West Nile virus strains found in an alpaca and a crow. The study, published in Frontiers in Veterinary Science, sheds light on the diversity of virus strains circulating among different animal species and geographic locations.
The investigation began when the Connecticut Veterinary Medical Diagnostic Laboratory (CVMDL) received eight cases of West Nile virus for diagnosis in 2021. These cases included both domestic and wild birds, as well as a single alpaca. Driven by the unique cohort of cases, Natalie Tocco, a resident in anatomic pathology at the Department of Pathobiology and Veterinary Science, and her team decided to explore research avenues related to the West Nile virus.
Among the cases, the alpaca from Massachusetts and a crow from Connecticut exhibited the highest viral loads at the time of diagnosis. The researchers focused on these two cases to investigate potential genetic differences between the strains found in different species and states.
By sequencing the complete genomes of the viruses, the team compared them to existing data. The West Nile virus identified in the crow displayed similarities to a virus previously found in mosquitoes and birds in New York between 2007 and 2013. However, the virus found in the alpaca resembled West Nile viruses discovered in mosquitoes from New York, Texas, and Arizona between 2012 and 2016.
"[These findings] show the variety of the strains that are circulating and that can really alter what we see in the populations of what mosquitoes are dragging around in different areas," explained Tocco.
The knowledge gained from this research has the potential to aid scientists in predicting the emergence of different strains of the virus based on the movement patterns of mosquitoes and birds across the country.
The researchers determined that differences in the genetic makeup of the viruses indicate that vector-host feeding preferences likely drive viral transmission. Distinct mosquito species exhibit preferences for specific animal hosts, leading to the infection of multiple animal species by various West Nile virus strains.
Tocco emphasized the need for further investigation to uncover the patterns associated with different strains of the virus and the diseases they cause. "It could open up a whole can of worms," she said. "In reality, I think we need to do more research on that to see what we’re finding and what kinds of patterns we should expect in terms of the different strains and what kind of diseases we see with those."
First detected in New York City in 1999, West Nile virus rapidly spread throughout the United States and reached Connecticut by 2000. Since then, it has remained a significant public health concern in the country. During the early 2000s, the CVMDL published one of the initial papers on West Nile virus in the United States. Tocco highlighted the importance of conducting research on this virus through the analysis of diagnostic cases, not only as a public health concern but also as a means to advance knowledge in the field.
Despite only focusing on two cases during the study, the researchers are currently working on another paper that will analyze the specific symptoms observed in all eight cases.
The number of West Nile virus cases diagnosed by the CVMDL varies each year, with a higher incidence during wet summers when mosquito populations thrive. In 2022, the laboratory diagnosed 30 cases. Birds, especially corvids like crows, ravens, and jays, are commonly known carriers of West Nile virus. Symptoms observed in these animals typically include seizures, paralysis, neurological abnormalities, and ocular signs. Raptors, such as eagles, owls, and hawks, are particularly susceptible to eye-related symptoms and heart disease caused by the virus.
"There’s a variety of lesions we can see with West Nile so it’s more about being proactive with these diagnostic cases at certain times of year and keeping on high alert because it’s not just the nervous system signs in some animals," Tocco noted.
Although the typical West Nile virus season occurs between August and October, the changing climate in Connecticut is expanding the virus's range. Tocco has diagnosed West Nile cases as early as May and as late as November. These cases may serve as indicators of future trends, urging researchers to remain open to a broader window for potential infections.
The genetic analysis of West Nile virus strains found in an alpaca and a crow has provided valuable insights into viral transmission dynamics and the diversity of strains in different species and regions. This research contributes to the understanding of host preferences among mosquitoes and emphasizes the importance of ongoing investigations to anticipate disease patterns and potential outcomes for affected animals and public health.
The investigation began when the Connecticut Veterinary Medical Diagnostic Laboratory (CVMDL) received eight cases of West Nile virus for diagnosis in 2021. These cases included both domestic and wild birds, as well as a single alpaca. Driven by the unique cohort of cases, Natalie Tocco, a resident in anatomic pathology at the Department of Pathobiology and Veterinary Science, and her team decided to explore research avenues related to the West Nile virus.
Among the cases, the alpaca from Massachusetts and a crow from Connecticut exhibited the highest viral loads at the time of diagnosis. The researchers focused on these two cases to investigate potential genetic differences between the strains found in different species and states.
By sequencing the complete genomes of the viruses, the team compared them to existing data. The West Nile virus identified in the crow displayed similarities to a virus previously found in mosquitoes and birds in New York between 2007 and 2013. However, the virus found in the alpaca resembled West Nile viruses discovered in mosquitoes from New York, Texas, and Arizona between 2012 and 2016.
"[These findings] show the variety of the strains that are circulating and that can really alter what we see in the populations of what mosquitoes are dragging around in different areas," explained Tocco.
The knowledge gained from this research has the potential to aid scientists in predicting the emergence of different strains of the virus based on the movement patterns of mosquitoes and birds across the country.
The researchers determined that differences in the genetic makeup of the viruses indicate that vector-host feeding preferences likely drive viral transmission. Distinct mosquito species exhibit preferences for specific animal hosts, leading to the infection of multiple animal species by various West Nile virus strains.
Tocco emphasized the need for further investigation to uncover the patterns associated with different strains of the virus and the diseases they cause. "It could open up a whole can of worms," she said. "In reality, I think we need to do more research on that to see what we’re finding and what kinds of patterns we should expect in terms of the different strains and what kind of diseases we see with those."
First detected in New York City in 1999, West Nile virus rapidly spread throughout the United States and reached Connecticut by 2000. Since then, it has remained a significant public health concern in the country. During the early 2000s, the CVMDL published one of the initial papers on West Nile virus in the United States. Tocco highlighted the importance of conducting research on this virus through the analysis of diagnostic cases, not only as a public health concern but also as a means to advance knowledge in the field.
Despite only focusing on two cases during the study, the researchers are currently working on another paper that will analyze the specific symptoms observed in all eight cases.
The number of West Nile virus cases diagnosed by the CVMDL varies each year, with a higher incidence during wet summers when mosquito populations thrive. In 2022, the laboratory diagnosed 30 cases. Birds, especially corvids like crows, ravens, and jays, are commonly known carriers of West Nile virus. Symptoms observed in these animals typically include seizures, paralysis, neurological abnormalities, and ocular signs. Raptors, such as eagles, owls, and hawks, are particularly susceptible to eye-related symptoms and heart disease caused by the virus.
"There’s a variety of lesions we can see with West Nile so it’s more about being proactive with these diagnostic cases at certain times of year and keeping on high alert because it’s not just the nervous system signs in some animals," Tocco noted.
Although the typical West Nile virus season occurs between August and October, the changing climate in Connecticut is expanding the virus's range. Tocco has diagnosed West Nile cases as early as May and as late as November. These cases may serve as indicators of future trends, urging researchers to remain open to a broader window for potential infections.
The genetic analysis of West Nile virus strains found in an alpaca and a crow has provided valuable insights into viral transmission dynamics and the diversity of strains in different species and regions. This research contributes to the understanding of host preferences among mosquitoes and emphasizes the importance of ongoing investigations to anticipate disease patterns and potential outcomes for affected animals and public health.