VOLUME 1, No.1 VIRAL EPlZOOTlCS IN SHRIMP - Central Institute ...

inn) small subunits and chesc are utiliz~d forspthesk of che \iral nucleic acid. Thus, che \irdnucleic acid is repliatd many fines. \lira1 DNAalso directs the cell (through nicsscngr KNA)to s!nthcsu*. protcuis that arc required for itscoat. Thus, the complcrc \iruscs are pnxluccdusing nc\\.ly formed topic.\ of tirat nuclcic nc~d\viU hc. rclc.z\cd outside up)n rupture of rhc ccll\vhicIi cxi infect frcsll Iic~lrhy cells to continuethe cycle. \'iru\cl\ hy d~ni~~cl\.c\ cxinor po\v ornlulnyly xq hacrcr~n or othcr lijing orgmilsnls rlo.Ilpon cntn, into the hosr ccll, rhc \.iruscshring ahout sc\,crnl ch.uigcs i\.irlii~i the ccll.\'arious al.rnorm.ll grnnulcs call he oliscr\fcd\virli~n vlms ~nfcctcd cells. Tlic\c inclusions mayhc. agpcgntc of \~n~\c\ or ~norlifiril ~,c.llul.~rco~nponcnt~. The ty[x'\ of thcsc ~nclusion\ ,111rltlic~r IOditlOll \\.1tll111 the CCIItoeach \.irurcs.RTC ~llar.iitc~-~st~i'The \.iru\c\ thus ilctroy the cells ofdifirc~ir tissuu. ((iiscqi~cnrl!; the f~~ncrion\ ofthe organs of \hrinil> nrc .ilfccrcd Icad~ng ro~i1sc.1~~ :LI~LI 17s q\~nipto~n\. The \prcn~l of' \,trus~nfkt~on is so f.nr rhar 111 thc cnc of ycllo\\, lic.lilor the \\.li~rc 5por. vlru.\ ~nfcct~ons (;il,out 3-4d~y~i.How viral diseases spread in theshrimps?injuries on the M y . Once inside the body cavityof shrimp, the viruses may hc carricd to thcirtarget organs through haclniolymph.Recent viral disease outbreaks inIndian Shrimp farmThc epi./~x)ric..\ affccring the shrimp f,mnsin niost of rli~ 11i.iriri1iic states of OIU cou11trydur~ng the p.~\t n180 yc.lrs ha\^ ken caused byvin~sm, ~nor.ihly, thc ycllo\v head-like virus N I ~tlic systcnilc cctodcrm.il and ~i~csoderrnalliaculo\~iri~\ .\(u.liitc spot discz~).Yellow head(YHD)-like diseaseTlic first m.ijor cpixootic of culturedsliri~iiliw~i 1nd1.1 \\,.L\ rccordcrl rluring Julj, roSclitcnil~r 1994 111 rlic slirinili far~ns .ilong thcK.in~l.llcru creek arc.1 111 Ncllorc riisrrict ofAnii1ir.1 1'r.iJcsIi. 'l'lic cliin)otic tiger shrimp,I1cn.lcu\ niontxlori \fpn.ilfccrcd by the disexqe.Al.i\r nio-tal~y of shrinip was artrihutcd to1~r1111ary \'irnl infection hllowcrl by sccon~iqIi~crcr1~1 infection. Sliri~iips \irere lost ~ ithi~i 3.5d.iy\ of ~nirial niort.lliry It was not possible fortl~r f.irnicrs to Jctcct rlic onsct of rI~\easc sincetlic affected \lirinilis d~d not cxhihit any\ynil>tonis. AItIiougli I>.lttcrn of disc;~+c ;11idriiortnliry u,crc \inlilar to rlic yclloi\~ licad diseaserclx)rtcd frorii 'IIi.~il.uid, the Kandalcrn cl~sea..cniarkcdly dilfcrcd froni Y HI) in li~stoparhologySninll crust.iccans and othcr aquaticorg.~nisnis Inn!. c.uy shrimp parhogc~lic \.ir~~\c\nnri ~f tlirsc enter i~~lturc ponds can i.lu\c1111i.it101ls m h~~ltli!. slir~mp. Hc.dthy sIirinil>sWhite spot diseasebllrhirc spot disci~sc, scientifically hiown asS!S~CIIIIC r~toclcr~ii.iI anrl nicsoder~nalliaculovirus (SthlI3\') h.~\ Ixcn the major causeInn!. hc .affected h! fccd~ng on 111f~it~rl dead of Iargc \talc niortalitio of ct~lrurcd shrimps inaqunrlc an~mals or cannih~l~snl o~infcctcdnlorihund ,urimals. I'iral d~seztm in groiv-ourpolid Inn!, also lie rr.uis~nittcd through h~rds,\vllicli may plik up infcctcd and dead slirirnptand drop them in uriinfcetcd ponds. Infccticjnmay also take place when the Iv~mpt injcstpathogenic \.iru\cs prescnt in the contaminatedrearing i\.atcr. The iirusa may gin cntr!. intothe shrimps rhrough abrasions, wounds orIndia. The discz\c i4.s firsr reported stx)~i dterthe onset of Norrhc,zct Inonsoon in Novcmber1904 from some shrimp farnis in Nellorc area.S~ncc tlicn, rliis L~ISCA\C lia ra\lagcd shrimp farmsin al~nosr all the niarit~me statcs of our countryand 11.u bee11 rcsponsiblc for hruigi~ig dewshrimp prtduction from the culrurc sector.Unlike the YHI), wlicih affects only I? mo~i(*n,this di5c.u~ affects both tiger and white shrimps