seal parvovirus

Clinical and molecular epidemiology of seal parvovirus infection in seals

of Northwestern Europe

Rebriarina HapsariProf. dr. A.D.M.E Osterhaus, DVM (supervisor)

R. Bodewes, Ph.D, DVM (supervisor)

A novel parvovirus was found in the brain tissue of a harbor seal

Bodewes, et al. PLOS One, 2013

A novel parvovirus was found in the brain tissue of a harbor seal

Erythroparvoviruses

AsymptomaticErythema infectiosum

Arthritis

Fetal hydropsHealthy

???

AnemiaIn non-human

primates

Aplastic crisis

CNS disease

???

Our hypotheses: Seal parvovirus…

has been circulating among seals for at least 10 years

gives clinical manifestations of anemia or low red blood cell count in seals

has an evolutionary pattern similar to other parvoviruses

*PDV epizootic years in North-Western Europe

Seal sera (2002-2014)

Seal spleen tissues (1988*, 2002*, 1989-2001)

Seal parvovirus screening and herpesvirus detection

Genome sequencing and phylogenetic analysis

LIPS assay development

Clinical, hematological, and pathological description

Samples Molecular Analysis Clinical picture analysis

Low prevalence of seal parvovirus in sera samples

2002

2003

2004

2005

2006

2007

2008

2009

2011

2012

2013

2014

0

4

8

12

16

20

Harbor seals (PV) n=131Grey seals (HG) n=69

Year

Num

ber o

f se

al s

era

test

ed

Prevalence of 0.5%

*

*

*

Prevalence of 8%

Seal parvovirus was more prevalent in seal spleen tissue samples

Table overview of clinical parameters and pathological diagnoses

Sample ID Sex Age Sample

Co-infection with Pathological diagnoses and/or

major clinical signs PDV PhHV-1

PV880823.6 NI NI spleen NI - NI


HG020628.02 F (sub)adult spleen - - Acute non-infectious cause of dead (possible drowning)

PV020628.13 M (sub)adult spleen - + Intestinal volvulus

PV020718.12 F juvenile spleen + + Extensive, acute, severe, interstitial pneumonia

PV020719.08 F (sub)adult spleen + + Extensive, acute, severe, interstitial pneumonia

PV020719.09 M (sub)adult spleen + - Extensive, acute, severe, interstitial pneumonia

PV020919.03 F (sub)adult spleen + -Euthanized due to presence of severe neurological

signs, PDV detected in the brain

PV021004.1 M (sub)adult spleen - -Emaciation; diffuse, subacute, marked, purulent

bronchopneumonia

HG06-130 F juvenile serum - -Several wounds on flippers and skin lesions suggestive

of pox virus infection

PV12-410* M juvenile serum and spleen - - Chronic, mild, non-suppurative meningo-encephalitis

PV121216.01* F juvenile spleen - +Acute, moderate necrotizing bronchitis and bronchiolitis

and acute interstitial pneumonia















bronchopneumonia




















bronchopneumonia




















bronchopneumonia






SePV from 1988-2012 displayed only one amino acid change in 1 most recent variant

12 (1.3%) variant nt positions in partial NS

13 (0.76%) variant nt positions in VP2, 1 amino acid change (S540T)

P. Norja, et.al. 2008

Seal parvovirus showed high substitution rate per site per year

Estimated nt substitution rate:

Partial NS = 2.00x10-4/site/year(HPD, 1.36x10-5-4.04x10-4)

VP2 = 1.15x10-4/site/year(HPD, 1.43x10-5-2.22x10-4)dN/dS=0.33

Discussion

Seal parvovirus has been circulating for more than 24 years among seals of Northwestern Europe

Low prevalence of 0.5% in the serum and 8% in the spleen tissue Relatively higher in PDV outbreak 2002 Seroprevalence?? LIPS assay hasn’t worked well

Low red blood cell count (RBC) was seen in two cases No more additional positive cases in a group of seals with low RBC

at admission

Neurological signs were in at least two cases Co-infection with PDV and/or PhHV-1, the spectrum of clinical

signs associated with SePV infection remained unclear

Discussion

Seal parvovirus has a high nucleotide substitution rates Similar to other parvoviruses, eg. B19, canine parvovirus type 2,

human bocavirus, etc. Only one amino acid change in the latest variant available from

2012 (S540T) strong negative selection

Minimal sequence variations of seal parvovirus found in harbor seal and grey seal

Similar to herpesviruses among phocids; and parapoxvirus in two species of pinnipeds

Metapopulation serves as single reservoir for the virus

Conclusions

Seal Parvovirus…

has been circulating in both harbor and grey seals since at least 1988

could not be attributed to any specific clinical manifestation

showed similar substitution rate to other parvoviruses but with a strong negative selection

Acknowledgments

Marco W.G. van de Bildt Thijs KuikenBart Haagmans

(virus discovery group)Miranda de Graaf Rogier Bodewes ADME Osterhaus

Ana Rubio GarciaGuillermo J. Sanchez-Contreras

Frank van VlietJan Nouwen

Submitted to PLoSONE on 14 August 2014

Our LIPS assay showed inconsistent results and high LU for the blank

The use of fresh antigen didn’t change the results

Buffers used in the assay did matter

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seal parvovirus