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Emerging infectious diseases2002; 8(4); 380-386; doi: 10.3201/eid0804.010239

Experimental infection of horses with West Nile virus.

Abstract: A total of 12 horses of different breeds and ages were infected with West Nile virus (WNV) via the bites of infected Aedes albopictus mosquitoes. Half the horses were infected with a viral isolate from the brain of a horse (BC787), and half were infected with an isolate from crow brain (NY99-6625); both were NY99 isolates. Postinfection, uninfected female Ae. albopictus fed on eight of the infected horses. In the first trial, Nt antibody titers reached >1:320, 1:20, 1:160, and 1:80 for horses 1 to 4, respectively. In the second trial, the seven horses with subclinical infections developed Nt antibody titers >1:10 between days 7 and 11 post infection. The highest viremia level in horses fed upon by the recipient mosquitoes was approximately 460 Vero cell PFU/mL. All mosquitoes that fed upon viremic horses were negative for the virus. Horses infected with the NY99 strain of WNV develop low viremia levels of short duration; therefore, infected horses are unlikely to serve as important amplifying hosts for WNV in nature.
Publication Date: 2002-04-25 PubMed ID: 11971771PubMed Central: PMC3393377DOI: 10.3201/eid0804.010239Google Scholar: Lookup
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  • Journal Article
  • Research Support
  • Non-U.S. Gov't
  • Research Support
  • U.S. Gov't
  • Non-P.H.S.

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The study experimented on the effects of West Nile virus (WNV) on horses, and concluded that due to low and short-lived viremia levels, infected horses may not serve as significant hosts for WNV amplification in nature.

About the Research

In this research, scientists aimed to investigate the role of horses in spreading West Nile virus by purposely infecting different breeds and ages of horses, and assessing the subsequent effects of the virus.

  • Twelve horses were deliberately infected with West Nile virus via bites from infected Aedes albopictus mosquitoes. The virus isolates used for infection were from two sources- one from the brain of a horse identified as ‘BC787’, and another from a crow brain identified as ‘NY99-6625’. Both isolates belonged to the NY99 strain of the virus.
  • Apart from this, clean, uninfected female mosquitoes were also allowed to feed on eight of these infected horses to study the potential transmission link.

Results of the Experiment

Findings from the experiment highlight how the horses responded to infection and how the virus was or wasn’t passed on to the mosquitoes that fed on them.

  • The examination of the horses’ antibody response showed variable results. In the first trial, the Nt antibody titers were calculated for horses ranging from 1:320 to 1:80. In the second trial, seven horses with subclinical infections (i.e., infections without apparent signs or symptoms) developed Nt antibody titers above 1:10 within 7 to 11 days post-infection.
  • The highest recorded viremia level, which is the presence of virus particles in the blood, in horses fed upon by the ‘recipient’ mosquitoes was estimated to be about 460 Vero cell PFU/mL.
  • Interestingly, the mosquitoes that had fed on viremic horses did not contract the virus, revealing a potential barrier to mosquito-borne transmission.

Conclusion

The culmination of the experiment points to a conclusion that emphasizes the limited role of horses in the natural amplification cycle of West Nile virus.

  • Examining the two key points from the results — the low viremia levels in horses and the absence of the virus in mosquitoes that had fed on viremic horses — the researchers posit that horses infected with the NY99 strain of West Nile virus do not play a significant role in enhancing the availability and spread of the virus in nature.

This research provides important insights for disease control strategies and furthers our understanding of the complex dynamics between hosts, vectors, and viruses.

Cite This Article

APA
Bunning ML, Bowen RA, Cropp CB, Sullivan KG, Davis BS, Komar N, Godsey MS, Baker D, Hettler DL, Holmes DA, Biggerstaff BJ, Mitchell CJ. (2002). Experimental infection of horses with West Nile virus. Emerg Infect Dis, 8(4), 380-386. https://doi.org/10.3201/eid0804.010239

Publication

ISSN: 1080-6040
NlmUniqueID: 9508155
Country: United States
Language: English
Volume: 8
Issue: 4
Pages: 380-386

Researcher Affiliations

Bunning, Michel L
  • Centers for Disease Control and Prevention, Atlanta, GA 30333, USA. mbunning@cdc.gov
Bowen, Richard A
    Cropp, C Bruce
      Sullivan, Kevin G
        Davis, Brent S
          Komar, Nicholas
            Godsey, Marvin S
              Baker, Dale
                Hettler, Danielle L
                  Holmes, Derek A
                    Biggerstaff, Brad J
                      Mitchell, Carl J

                        MeSH Terms

                        • Aedes / physiology
                        • Aedes / virology
                        • Animals
                        • Antibodies, Viral / blood
                        • Antibodies, Viral / immunology
                        • Bird Diseases / virology
                        • Brain / virology
                        • Chlorocebus aethiops
                        • Female
                        • Horse Diseases / blood
                        • Horse Diseases / immunology
                        • Horse Diseases / transmission
                        • Horse Diseases / virology
                        • Horses / blood
                        • Horses / immunology
                        • Horses / virology
                        • Insect Vectors / physiology
                        • Insect Vectors / virology
                        • Male
                        • Saliva / immunology
                        • Saliva / virology
                        • Songbirds / virology
                        • Vero Cells
                        • Viremia / blood
                        • Viremia / immunology
                        • Viremia / transmission
                        • Viremia / virology
                        • West Nile Fever / blood
                        • West Nile Fever / immunology
                        • West Nile Fever / transmission
                        • West Nile Fever / virology
                        • West Nile virus / immunology
                        • West Nile virus / physiology

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