PMID- 34065570
OWN - NLM
STAT- MEDLINE
DCOM- 20210816
LR  - 20210816
IS  - 1999-4915 (Electronic)
IS  - 1999-4915 (Linking)
VI  - 13
IP  - 5
DP  - 2021 May 20
TI  - Reduction in Virulence over Time in Ostreid herpesvirus 1 (OsHV-1) Microvariants 
      between 2011 and 2015 in Australia.
LID - 10.3390/v13050946 [doi]
LID - 946
AB  - Microvariant genotypes of Ostreid herpesvirus 1 (OsHV-1) are associated with mass 
      mortality events of Pacific oysters in many countries. The OsHV-1 microvariant 
      (microVar) emerged in France 2008 and caused significant economic losses as it became 
      endemic and displaced the previously dominant OsHV-1 reference genotype. 
      Recently, considerable genotypic variation has been described for OsHV-1 
      microvariants, however, less is known about variation in viral phenotype. This 
      study used an in vivo laboratory infection model to assess differences in total 
      cumulative mortality, peak viral load, transmissibility, and dose-response for 
      three OsHV-1 isolates obtained between 2011 and 2015 from endemic waterways in 
      Australia. This followed field observations of apparent reductions in the 
      severity of mass mortalities over this time. Significantly higher hazard of death 
      and cumulative mortality were observed for an isolate obtained in 2011 compared 
      to isolates from 2014-2015. In keeping with other studies, the hazard of death 
      was higher in oysters challenged by injection compared to challenge by 
      cohabitation and the mortality was higher when the initial dose was 1 x 10(4) 
      OsHV-1 DNA copies per oyster injection compared to 1 x 10(2) DNA copies. There 
      was no difference in the quantity of OsHV-1 DNA at time of death that could be 
      related to isolate or dose, suggesting similar pathogenetic processes in the 
      individual oysters that succumbed to end-stage disease. While the isolates 
      examined in this study were biased towards pathogenic types of OsHV-1, as they 
      were collected during disease outbreaks, the variation in virulence that was 
      observed, when combined with prior data on subclinical infections, suggests that 
      surveillance for low virulence genotypes of OsHV-1 would be rewarding. This may 
      lead to new approaches to disease management which utilize controlled exposure to 
      attenuated strains of OsHV-1.
FAU - Cain, Georgia
AU  - Cain G
AD  - Sydney School of Veterinary Science, The University of Sydney, Camden 2570, 
      Australia.
FAU - Liu, Olivia
AU  - Liu O
AD  - Sydney School of Veterinary Science, The University of Sydney, Camden 2570, 
      Australia.
FAU - Whittington, Richard J
AU  - Whittington RJ
AD  - Sydney School of Veterinary Science, The University of Sydney, Camden 2570, 
      Australia.
FAU - Hick, Paul M
AU  - Hick PM
AD  - Sydney School of Veterinary Science, The University of Sydney, Camden 2570, 
      Australia.
LA  - eng
PT  - Historical Article
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20210520
PL  - Switzerland
TA  - Viruses
JT  - Viruses
JID - 101509722
RN  - Ostreid herpesvirus 1
SB  - IM
MH  - Animal Diseases/*epidemiology/history/*virology
MH  - Animals
MH  - Australia/epidemiology
MH  - DNA Virus Infections/*veterinary
MH  - DNA Viruses/*genetics/isolation & purification/*pathogenicity
MH  - *Genetic Variation
MH  - History, 21st Century
MH  - Kaplan-Meier Estimate
MH  - Mortality
MH  - Ostreidae/*virology
MH  - Proportional Hazards Models
MH  - Public Health Surveillance
MH  - Virulence
PMC - PMC8160646
OTO - NOTNLM
OT  - Crassostrea gigas
OT  - Ostreid herpesvirus 1
OT  - Pacific oyster
OT  - phenotype
OT  - virulence
COIS- The authors declare no conflict of interest. The funders had no role in the 
      design of the study; in the collection, analyses, or interpretation of data; in 
      the writing of the manuscript; or in the decision to publish the results.
EDAT- 2021/06/03 06:00
MHDA- 2021/08/17 06:00
PMCR- 2021/05/20
CRDT- 2021/06/02 01:13
PHST- 2021/04/12 00:00 [received]
PHST- 2021/05/06 00:00 [revised]
PHST- 2021/05/17 00:00 [accepted]
PHST- 2021/06/02 01:13 [entrez]
PHST- 2021/06/03 06:00 [pubmed]
PHST- 2021/08/17 06:00 [medline]
PHST- 2021/05/20 00:00 [pmc-release]
AID - v13050946 [pii]
AID - viruses-13-00946 [pii]
AID - 10.3390/v13050946 [doi]
PST - epublish
SO  - Viruses. 2021 May 20;13(5):946. doi: 10.3390/v13050946.