Senecavirus A (SVA), aka Seneca Valley Virus (SVV)

Test code: S0270 - Ultrasensitive qualitative detection of Senecavirus A by reverse transcription coupled real time polymerase chain reaction

Senecavirus A (SVA), also known as Seneca Valley Virus (SVV), is a non-enveloped, positive-sense single-stranded RNA virus in the genus Senecavirus within the Picornaviridae family. The virus was first identified in 2002 as a cell culture contaminant, likely from porcine trypsin or fetal bovine serum. Since then, SVA has been detected in swine in the United States, Canada, Brazil, China, Thailand, and other countries. Although animals infected with this virus develop symptoms very similar to those caused by the foot-and-mouth disease virus (FMV), SVA is not zoonotic, and it is imperative to differentiate the two diseases through diagnostic testing.

SVA primarily affects pigs and is associated with porcine idiopathic vesicular disease (PIVD), with symptoms similar to foot-and-mouth disease (FMD), including fluid-filled vesicles, erosions, and ulcers on the snout, coronary bands, and hooves, as well as lameness, fever, and lethargy. SVA can also lead to transient neonatal mortality in piglets less than 7 days old, with symptoms such as lethargy, diarrhea, neurological signs, or sudden death, resulting in mortality rates of 30–70% in affected litters.

The virus can be transmitted through direct contact, particularly via oral or nasal secretions; the virus is also shed in feces. Because the virus is stable in the environment, contaminated equipment, clothing, and surfaces can transmit SVA. Ingestion of contaminated feed, water, or feces is also a pathway. Rodents, houseflies, and other pests may act as mechanical vectors, carrying the virus between locations or between herds. Limited evidence suggests the possibility of short-distance airborne spread by aerosols, particularly in high-density farm settings. Vertical transmission from sows to piglets has been suspected but not fully confirmed.

Serological tests, such as ELISA and virus neutralization, detect antibodies to SVA but are not suitable for rapid outbreak response since it takes time for the infected animals to develop antibodies. Serological tests cannot be used for environmental screening. Virus isolation in cell culture can confirm SVA but is rarely used for routine diagnostics because it is time-consuming and not very sensitive. PCR is the preferred method as it is highly specific and sensitive (Bracht et al., 2016; Mu et al., 2020).

Utilities:

• Help confirm the disease causing agent
• Environmental monitoring
• Help ensure that swine herds are free of Senecavirus A
• Early prevention of spread of this virus among swine populations
• Minimize human exposure to this virus
• Safety monitoring of biological products that derive from pigs

References:
Bracht, A. J., O'Hearn, E. S., Fabian, A. W., Barrette, R. W., & Sayed, A. (2016). Real-time reverse transcription PCR assay for detection of Senecavirus A in swine vesicular diagnostic specimens. PLoS ONE, 11(1), e0146211..

Mu, S., Abdullah, S. W., Zhang, Y., Han, S., Guo, H., Li, M., et al. (2020). Development of a novel SYBR green I-based quantitative RT-PCR assay for Senecavirus A detection in clinical samples of pigs. Molecular and Cellular Probes, 53, 101643.

Specimen requirements: 0.2 ml feces, or rectal swab, or oral swab, or respiratory swab, or 0.2 ml fresh or frozen tissue, or 0.2 ml cell culture.

Contact Zoologix if advice is needed to determine an appropriate specimen type for a specific diagnostic application. For specimen types not listed here, please contact Zoologix to confirm specimen acceptability and shipping instructions.

For all specimen types, if there will be a delay in shipping, or during very warm weather, refrigerate specimens until shipped and ship with a cold pack unless more stringent shipping requirements are specified. Frozen specimens should be shipped so as to remain frozen in transit. See shipping instructions for more information.

Turnaround time: 2 business days

Methodology: Qualitative reverse transcription coupled real time PCR

Normal range: Nondetected