Early pathogenesis of Venezuelan equine encephalitis virus infection in horses

2004 2004

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Abstract (summary)

In horses, it is not known which tissues support Venezuelan equine encephalitis virus (VEEV) replication during the early stages of disease, nor how the virus gains access to the CNS. My research focused on the early viral titers in tissues, the interferon response in horses and diagnosis of VEEV viremia by a quantitative RT-PCR.

Two horses each were challenged with the virulent Trinidad donkey strain of VEEV, and two sacrificed at 24, 48, 96 and 144 hours post challenge. Viremic titers peaked at 103.8 to 104.5 PFU/mL between 60 and 72 hours after challenge. VEEV titers peaked in the draining lymph nodes (103.9 to 106.1 PFU/g tissue) at 24 to 48 hours. Highest tissue titers were noted in the bone marrow (106.2 to 108.6 PFU/g) at 48 and 96 hours, the olfactory bulb (106.5 PFU/g) and tract (106.8 PFU/g) at 96 hours post challenge. Virus was detected in the dental pulp (102.8 to 105.1 PFU/g), trigeminal nerve (102.9 to 103.6 PFU/g), and olfactory tract and bulb, prior to detection of virus in the cerebrum. This data indicates the virus replicates in the lymph nodes and bone marrow, prior to entry into the CNS through the olfactory and trigeminal nerves.

The serum interferon (IFN) responses were assayed in horses challenged with four strains of VEEV, the TrD strain, a non-virulent IE strain, a virulent IE strain, and the V3526 vaccine strain. IFN response was greatest (320–1280 IU/mL) for the TrD strain challenge. The initiation, peak, and length of serum IFN titers in horses challenged with TrD correlated with the initiation, peak and length of viremic titers. Virulent IE VEEV challenge of three horses resulted in no detectable serum IFN response, although clinical illness was severe in the horses. The avirulent IE and V3526 VEEV strains resulted in a low, transient but detectable IFN response. Results of the quantitative RT-PCR indicate viral antigen can be detected in horse sera at titers as low as 2.0 PFU/mL.

Indexing (details)

Veterinary services;
Animal diseases
0410: Microbiology
0778: Veterinary services
0476: Animal diseases
Identifier / keyword
Biological sciences; Equine encephalitis virus; Horses; Pathogenesis
Early pathogenesis of Venezuelan equine encephalitis virus infection in horses
Teehee, Max L.
Number of pages
Publication year
Degree date
School code
DAI-B 66/01, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
9780496931965, 0496931962
Bowen, Richard
Colorado State University
University location
United States -- Colorado
Source type
Dissertations & Theses
Document type
Dissertation/thesis number
ProQuest document ID
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
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