Ultra Structure of White Spot Syndrome Virus

8/6/2019 Ultra Structure of White Spot Syndrome Virus

1/14


2/14


3/14


4/14


5/14


6/14


7/14

Wang et al.: In vitro propagatio n of WSSV 97

Fig. 4 (facin gpag e, above, an d next page). Electron micrographs of th e 6 types of cultu red lymphoi d cells of Pen aeus monodo n,showing (A )Fibroblast-like cells, (B ) phagocyte, (C ) granulocyte, (D ) reticular cells, (E l , E2) large an d small cells, respectively,with pycnotic nuclei and (F) adipose cells. C l : collagen-lik e fibers; C2: collagen-like fibers with amorph ic matrix; D: desmosome-like junction; G: granu le; GB: Golgi body; L: lipid droplet; M: mitochondria; N: nucleus;NM : nuclear memb rane; Nu: nucleolus;P: phagosome; Ph: phagocy te; rER: rough endoplasm ic reticulunl; sER; smooth endoplasmic reticulum; VL : large vacuole in fibro-blast-like cell. Scale bar = 1 pm


8/14

Dis Aquat Org 41.91-104,200 0

Fig. 4 (continued)

able 3. WSSV infection prevalence of 6 different cell types in 250 observed cultured lymphoid cells at 3 d post-inoculation

revalence cell typeFibroblast- Phagocyte Granulocyte Reticular Denso- Adipocytelike cell cell nuclear cell

nfected celIs/total 2/250 0/250 5/250 2/250 0/250 3750bserved cells (% ) (0.8) (0.0) (2.0) (0.8) (0.0) (1.2)nfected cells/ 2/11 0/83 5/89 2/25 0/14 3/28ell-type total (% ) (18.2) (0.0) (5.6) (8.0) (0.0) (10.7)

Fig. 5. Electron micrographs of WSSV-infected cultured lymphoid cells of Penaeusmonodon at 3 d post-inoculation. (A) Fibro-blast-like cell, (B ) granulocyte, (C ) reticularcell, and (D ) adipose cells. Cl: collagen-likefibers; F: fibrillar mass; G: granule; L: lipiddroplet;M: mitochondria; MB: multivesicular

body; V: virion. Scale bar = 1 pm


9/14

Wang et al.: In vitro propagation of WSSV 99

(6) Adipose cells (Ad cells, Fig. 4F)were electron-lu cent, and ha d few cyto-plasmic processes. Their cytoplasm con-tained many lipid droplets, secondarylysosomes and smooth endoplasmicreticulum.

Based on electron microscopic obser-vation of these uninfected, control pri-mary cultured lymphoid cells at 4 d afterinitial seeding, G r cells accounted forabout 35.6% of the population. Nextmost common were Ph cells (33.2%),followed by Ad cells (11 .2%) , Re cells(10. 0%) , Pn cells (5 .6%),and F cells(4.476).The electron micrographs of theinfected cultured lymphoid cells at 3 dpost-inoculation were examined an d theWSSV infection per centag e was also de-termined (Table 3). Except for Ph cellsand Pn cells, all the other cells were sus-cepti ble to WSSV infection (Figs. 5A-D& 6A-C). Infected Gr cells accounted for2.0% of 250 observed cells. Next wereinfected Ad cells ( 1 . 2%) , followed by Fcells (0.8% ) nd Re cells (0.8% ).On theother hand , cornpallson of cell type in-fection prevalence showed that 18% ofF cells (2/11 )were infected followed byl l % Ad cells, 8% of Re cells and 6 % ofGr cells (Tab le 3). During the course ofinfection these susceptible cells all ex-hibited similar cytopathogen esis.

Early cytopathic changes associatedwith WSSV infection included increas-ing hypertrophy of the nucleus andmargination and diminution of nuclearchromatin. The hyp ertrophic nuclei ofWSSV-infected cells consisted of 2 dis-tinct areas: a marginal layer mad e up ofelectron-dense chromatin with severalspots of heterochromatin, and a cen-tral, homogenous, electron-lucent matrixarea with several clusters of developingvirions (Fig. 6A,B). This central are awas approximately round in sha pe, andits diameter depended on the progressof infection. In heavily infected cells(i.e. those full of mature virions), themarginal layer became very faintand often could not be seen by TEM(Fig. 6C). The infected cells alsoshowed enlarged perinuclear cisternaeand multivesicular bodies (F ig. 6A,B),an d, especially in heavily infected cells,degenerate organelles could be seen in


10/14

10 0 Dis Aquat Org 41: 91-104, 2000

the cytoplasm. No obvious virogenic stroma appeared the multivesicular bodies fused with th e outer nuclearin the nuclei of infected cells. Fibrillar masse s wer e not mem bran e and digital processes from them seemed tosee n in the nuclei, but in the cytoplasm multivesicular extend directly to the nuclear pore (Fig. 6B) . The cen-bodies containing 1 to 6 fibrillar masse s we re see n. In tral nuclea r areas of infected cells wer e filled withprofile, they appe ared as spiral coils. Thes e multivesic- many empty nucleocapsid shells (capsids; Figs. 6B &ular bodies also contained many electron-dense par- ?A) . Most of th ese empty capsids were su rrounde dticles 30 nm in diameter (Fig.6A ,B) .The membrane of loosely with an envelope, and both the shell and enve-


11/14


12/14


13/14


14/14

Documents

Ultra Structure of White Spot Syndrome Virus