Virus-like particles associated with marine mussel mortalities in New Zealand

Abstract

ABSTRACT. Green-lip mussel Perna canaliculus spat (15 to 30 m m length) in the outer Marlborough Sounds, New Zealand, suffered 50 to 100% mortal~t)! during January to April 1994 (summer/autumn) following thinning and reseeding of the mussel lines by farmers Adult mussel ~nortalities of 2 to 5 % continued from February to early h4ay 1994 Histolog~cal examination showed extensive haemocytosis and multifocal liquefact~on necrosls of i n t e r s t~t~a l cells, basal cells and digest~ve tubule ep~thelial cells. Sloughed pyknot~c 01-karyolyt~c digestive tubule epithelia1 cells formed charactenst~c rounded granular b o d~e s 10 to 15 pm diameter both In digestive tubules and free in lesions. No v~r a l inclusion bodies were observed Ultrastructural examination showed highly mod~fied rough endoplasn~ic reticulum assoc~ated with small, 25 to 45 nm diameter, electron-dense uncoated virus-like particles Identical cell damage and virus-like particles were subsequently found In moribund adult (75 to 110 mm length) P canallculus and stunted (25 to 47 mm length) subtidal 12-li'tilus galloprov~ncial~s from the same area.Following purification of extracts of the moribund spat b}! isopycnlc centl-ifugation in CsCI, large numbers of 25 nm diameter, unenveloped, virus pal-t~cles were scvn by electron mlcroscopy These part~cles had a density of 1.364 g cm-3 A broad band at a d e n s~t y c~xpected for enveloped particles (1 21 to 1 24 g cm ') was also observed but contained few v~rus-like particles Cell damage a n d mussel mortalit~es are thus likely due to a small unenveloped virus.

Prokaryote infections in the New Zealand scallops Pecten novaezelandiae and Chlamys delicatula

“…A subsequent ultrastructural study revealed the presence of virus-like particles (V-LPs) in sloughing cells (Hine & Wesney 1997). As similar V-LPs were previously reported to be associated with mortalities among cultured mussels Perna canaliculus (Jones et al 1996), the V-LPs in scallops may cause excessive sloughing and mortalities. However, subsequent observations on P. novaezelandiae showed that many sloughing digestive epithelial cells also contained prokaryotes, in the presence or absence of V-LPs.…”

Differential effects of adult mussels on the retention and fine-scale distribution of juvenile seed mussels and biofouling organisms in long-line aquaculture

“…3 in the present study, Buchanan & Babcock 1997). Losses of juvenile mussels from aquaculture substrata could also be due to other factors that include variations in genetics and fitness among individuals (Phillips 2002, Alcapán et al 2007, Sim-Smith & Jeffs 2011, disease (Jones et al 1996), predation pressure (Hayden 1995, Peteiro et al 2010, biofouling (Fitridge et al 2014) and stressors associated with the relay of juveniles from the hatchery or wild collection sites to the nursery farm location that might increase mortality or trigger secondary settlement (Webb & Heasman 2006, Carton et al 2007). Quantifying the relative importance of the causes of loss has not been satisfactorily achieved in this and other studies and remains an important research priority.…”

Virus-like particles associated with mortalities of the Manila clam Ruditapes philippinarum in England

“…Elston (1997) suggested a resemblance of these virus particles with picornaviruses. The absence of mitochondrial inclusions and arrays and the characteristic proliferation of endoplasmic reticulum suggest that the New Zealand virus may be different from that reported in Denmark (Jones et al 1996). Hine & Wesney (1997) reported cytological changes in scallops Pecten novaezelandiae and toheroa Paphies ventricosum similar to those reported from Perna canaliculus in New Zealand.…”

“…Mortalities of cultivated seed and adult greenlipped mussels Perna canaliculus in New Zealand were associated with large numbers of unenveloped particles (Jones et al 1996). Elston (1997) suggested a resemblance of these virus particles with picornaviruses.…”