q & a: cyprinid herpes virus-3 (cyhv-3) aka koi herpes virus (khv) · 2018-08-28 · 1. do high...

Q & A:

Cyprinid Herpes Virus-3 (CyHV-3)aka

Koi Herpes Virus (KHV)

Nick PhelpsOctober 13, 2017

Q: What is KHV?

Ilouze et al. ER. 2011.

Q: What is KHV?

Infected KF-1 Cells

-KF cell line at 25C

-Include gill tissue in sample

-Difficult to culture: 3+ blind passes

K. Way

Q: What is KHV?

N. Phelps

Columnaris

C. Banner

R. Holt

Q: Where did the KHV come from?

• Israel koi ponds in the mid 1990s…?• “The KHV cure”!

• Naturally Infected Fish (NIF)

• Effective management strategy?

60F

80F70F

90F

Ronen et al. Vaccine. 2003.

Hedrick et al. JAAH. 2000.Davidovich et al. AoV. 2007Sadler et al. JFD. 2008.Ilouze et al. ER. 2011.McColl et al. JFD. 2017

• Highly susceptible to disease• Common carp/koi

• Moderately susceptible to disease• Koi/Goldfish hybrid

• Potential carrier• Goldfish

• Resistant• Silver carp, black carp, tilapia, silver perch, many more fish and non-fish

• In vitro studies• Cell culture positive: Common carp, koi, silver carp, goldfish• Cell culture negative: Fathead minnow, channel catfish

Q: Does KHV affect native species of fish? Could minnows and other cyprinids be a carrier of KHV?

Q: The fish kills appear to be significant and unusually high suggesting KHV is being introduced to naïve populations?

• Population density and water temperature strongly influence mortality

• Expected mortality rates for naïve carp/koi populations:• Lab trials: 90-100%• Farm ponds: 80-100%• Wild populations: Unknown and highly variable, models estimate ~75%

Hedrick et al. JAAH. 2000.Sunarto et al. VR. 2014.

Q: What is KHV impact on aquaculture? If MN becomes a hot spot for KHV will it affect our ability to export fish to other areas that raise carp for food?

• Koi/carp: Huge economic losses worldwide, direct and indirect• Non-carp: Negligible impact

• OIE has KHV listed as a ’notifiable pathogen’, but they consider KHV endemic to the USA (= little regulatory oversight for international trade)

• USDA does not regulate KHV, but it is ‘reportable’• MN DNR does not regulate KHV

Q: What is KHV’s impact on commercial fishing?

• Locally, could reduce densities and be a problem. • However, there are many lakes with carp that have ongoing efforts by

managers to reduce/manage population levels...

Q: Why is KHV important?

Q: Why is KHV important?

Q: Why is KHV important?

PestSmart 2017

McColl et al. BC. 2014.

Q: Why is KHV important?

Q: How widespread is the disease?

• 1996: First reported in United Kingdom and from Israel farm ponds• 1998: First reported in USA• 2008: First reported in Minnesota hobby pond• 2017: First reported in Minnesota wild carp

• Today: Assumed global distribution (via koi trade). Sporadic mortality events in wild/captive fish across North America.

Q: How widespread is the disease?2017 UMN Carp surveys

= KHV Positive= Mortality event, not tested= KHV Negative

Q: Do these lakes have a history of carp kills?

• Elysian: -• Dora: -• Tetonka: 2006 (sunfish), 2007 (sunfish)• Washington: 2006 (crappie)• Gorman: -• Sabre: -• Cannon: 2007 (perch, minnow, drum, other)• Clear: 2007 (crappie/sunfish)

• **REPORT FISH KILLS!**

Q: How is KHV spreading to these other watersheds?

• Virus is viable in water for 4hrs, maybe up to 3 days • Virus is viable in hosts for years

• Movement of infected/carrier fish?• Birds?• Boat movement?• Aquaculture practices?

Pokovora et al. VM. 2005.Ilouze et al. ER. 2011.Phelps et al. NAJFM. 2014.

Q: We are seeing KHV pop up in many new places. Is this because we are now looking for it or is this something new and spreading?

• More likely: First time we are really looking• Less likely: Front line of invasion

• Both possible!

Q: What research is going on related to KHV?

• CSIRO: HUGE effort to evaluate KHV for carp biocontrol

• CEFAS: Diagnostics and epidemiology, focus on aquaculture

• Israel: Lab trials, control measures, focus on aquaculture

• U of FL: Molecular analysis and systematics of herpes viruses

• U of MN: 2013-2019 funded project… plus other side projects related to fish kills

Q: What research is going on?

• “Understanding the virome of carp species in the Upper Midwest”

1. Do high density invasive carp disrupt the ecology of endemic viruses?2. Are there species-specific viruses that could be used for biocontrol?

• Ongoing surveys of healthy and dead carp, as well as other fish kills• Many new viruses identified in the last few years

Phelps et al. PLoSOne. 2014.Mor et al. JVM. 2015.Mor and Phelps. AofV 2016.Mor and Phelps. AofV. 2016.Mor et al. AofV. 2017.

More questions?

Next steps…?