from the bench
Alaska communities, 160 miles apart
and both experiencing parvovirus
outbreaks. The hope was the lab’s NGS
technology could reveal whether they
were due to gaps in canine immunization,
a novel strain or possibly both.
The Alaska State Virology Lab is one
of a growing number of public health
labs with NGS technology. In a year, all
state labs are expected to have acquired
NGS technology, many with support
from the US Centers for Disease Control
and Prevention’s (CDC’s) Advanced
Molecular Detection (AMD) initiative.
Part of the early wave of adopters, the
Alaska State Virology Lab first brought
its NGS technology on site in 2014. The
lab is still in the process of validating
its use as an official diagnostic tool ,
rather than only a reference tool. The
parvovirus experiment helped move
that validation process forward, Chen
said, adding to a growing evidence base
that NGS technology can be effectively
used in outbreak investigation.
Canine Parvovirus
Parker noted that the NGS results did seem to match the parvovirus strains
used to make the canine vaccine, which means better immunization coverage
may have prevented or slowed the outbreaks.
To conduct the parvovirus study,
results from which were published last
August in Scientific Reports, Parker, Chen
and colleagues tested 12 rectal-swab
specimens from dogs involved in the
larger outbreaks and with clinical signs
consistent with parvovirus. Using NGS,
they were able to detect and characterize
replicating canine parvovirus in the
samples—that’s significant, Parker said,
because it means the virus was mostly
likely the cause of the dogs’ symptoms.
NGS also revealed two distinct subtypes
of parvovirus that were geographically
distant. The NGS results, coupled with
more traditional serological testing for
virus antibodies, suggested that the
outbreak wasn’t due to a novel strain of
parvovirus, but likely to exposures within
an under- or unvaccinated dog population.
Parker noted that the NGS results did
seem to match the parvovirus strains
used to make the canine vaccine, which
means better immunization coverage may
have prevented or slowed the outbreaks.
“It was surprising because we had
thought it was one giant outbreak,” Parker
said. “But instead, one community had
one virus and the other had a different
one—they were two distinct events.”
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Beyond demonstrating the capacity
for NGS in outbreak investigation, the
study also helped demonstrate its use
in post-mortem testing, said Chen, who
also serves as an associate professor
in the Department of Biology and
Wildlife at the University of Alaska-
Fairbanks. It’s difficult to find assays
validated for cadaver blood, Parker
said, but NGS was able to reveal reliable
information using rectal swab samples
from deceased canines. Overall, Parker,
Chen and study co-authors Molly
Murphy and Karsten Hueffer concluded
that the “NGS methodology proved
to be an effective diagnostic tool.”
While both the Fairbanks lab and the state
public health lab in Anchorage are still
validating their NGS methodology, they’re
the only labs in the state with the capacity
to use NGS in infectious disease outbreak
investigation. That’s important, Parker
said, because it will allow lab workers
to turnaround critical epidemiological
information much quicker than before.
For example, Chen said the lab hopes
to use NGS to better understand
transmission networks related to hepatitis
C infection, case counts of which have
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tripled nationally in the past few years
among young adults with a history of
injection drug use. If the Fairbanks lab can
use NGS to reveal a clearer geographic
picture of transmission risks, fellow public
health workers could more precisely
target hepatitis C prevention strategies,
such as disease screening and education.
In fact, the Fairbanks lab is already
immersed in such work as one of four
state labs participating in the CDC/APHL
project GHOST—Global Health Outbreak
and Surveillance Technology—which is
focused on hepatitis C transmission.
Back to the parvovirus outbreak, Parker
said the NGS results didn’t come out
until after the state’s big mushing races,
so researchers weren’t able to alleviate
any fears of a novel strain before the
dog-sledding races took off. Still, the
findings do underscore the importance of
keeping Alaska’s dogs fully immunized.
“Dog mushing is our state sport,” Parker
said. “Bad publicity can be really hurtful
to our communities and to our state, so
it’s important to everyone to get a handle
on it.” n
Winter 2018 LAB MATTERS
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