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The genus Megalocytivirus in the family Iridoviridae encompasses isolates of red sea bream iridovirus (RSIV) and grouper sleepy disease iridovirus (GSDIV). In the present study, humpback grouper Cromileptes altivelis juveniles were challenged with GSDIV after vaccination with a commercial RSIV vaccine. The unvaccinated group (in duplicate) showed higher mortalities (59.3 to 66.7%) than the vaccination group (0% mortalitiy, in duplicate). Surviving fish in the vaccinated group displayed masses of enlarged cells in the spleen. Electron microscopy revealed that they contained hemosiderin granules within the cytoplasm. In contrast, moribund fish from the unvaccinated group exhibited large numbers of inclusion body-bearing cells (IBCs) in the spleen, while surviving fish displayed masses of enlarged cells in which a small number of GSDIV virions were assembled. KEY WORDS: Humpback grouper · Cromileptes altivelis · Commercial RSIV vaccine · Grouper sleepy disease iridovirus · Enlarged cells Resale or republication not permitted without written consent of the publisherDis Aquat Org 79: [163][164][165][166][167][168] 2008 Chua et , Matsuoka et al. 1996, Danayadol et al. 1997, Kasornchandra & Khongpradit 1997, Chou et al. 1998, Jung & Oh 2000, Chao et al. 2002, Sano et al. 2002, Sudthongkong et al. 2002b, Weng et al. 2002, Chen et al. 2003, GibsonKueh et al. 2003, Shi et al. 2004. A diagnostic feature of megalocytivirus disease is the formation of inclusion body-bearing cells (IBCs) as well as necrotized cells, both of which are observed as enlarged cells by light microscopy (Miyazaki 2007).Recently, a commercialized formalin-inactivated RSIV vaccine has been shown to be highly efficient in protecting vaccinated red sea bream Pagrus major and other cultured marine fishes against RSIV disease (RSIVD) (Nakajima et al. 1997. However, the ultrastructural features of fish vaccinated against megalocytivirus were not investigated.In order to compare histopathological changes in unvaccinated, surviving fish after challenge with GSDIV with changes in surviving fish after being vaccinated and challenged with GSDIV, we undertook vaccination trials using a commercialized formalininactivated RSIV vaccine 'Biken' (The Research Foundation for Microbial Diseases of Osaka University, Kagawa, Japan). The present study describes the results of the vaccination test and ultrastructural features of the enlarged cells that developed in surviving fish of the vaccinated and unvaccinated groups. MATERIALS AND METHODSExperimental fish. For vaccination experiments, a total of 120 humpback grouper (mean body weight, 5 g) were obtained from a fish breeder in Bali Island. Ten samples of these were examined by PCR assay using a primer set for SJNNV (striped jack nervous necrosis virus) (Nishizawa et al. 1994) and for Pst I restriction fragment of RSIV genomic DNA (Kurita et al. 1998), and all were negative for the presence of NNV (nervous necrosis virus: Betanodavirus) and megalocytivirus.Virus stock. The GSDIV stock used in the experiment...

ABSTRAKPiscine nodavirus sebagai penyebab penyakit VNN (Viral Nervous Necrosis) dan iridovirus merupakan jenis virus yang dikenal menjadi penyebab utama kematian ikan laut yang dibudidayakan. Virus ini mampu menginfeksi ikan dari ukuran benih sampai ukuran konsumsi dan dalam waktu dua minggu, kematian mencapai 80% sampai 100%. Pada pembenihan larva dan benih ikan dalam skala rumah tangga ataupun hatcheri lengkap di sepanjang pantai di wilayah Bali Utara sering mengalami infeksi VNN dan iridovirus Namun, informasi terjadinya infeksi belum didata dengan baik. Tujuan penelitian ini untuk memperoleh data dan informasi mengenai peta infeksi atau serangan virus pada pembudidaya/pembenihan ikan sepanjang tahun 2017 di Bali Utara. Sampling dilakukan pada bulan Februari, Mei, Agustus, dan Oktober. Di samping melakukan sampling, juga dilakukan input data dari hasil analisis sampel di laboratorium bioteknologi yang diperoleh dari pemilik hatcheri/pembudidaya ikan. Analisis VNN menggunakan metode IQ Plus sedangkan analisis iridovirus dengan metode PCR konvensional dengan primer spesifik. Parameter yang diamati adalah prevalensi VNN dan iridovirus dari setiap hatcheri dan keramba jaring apung. Sebagai data penunjang pengukuran parameter kualitas air berupa suhu, salinitas, amoniak, dan nitrit yang dilakukan pada saat pengambilan sampel benih. Hasil penelitian menunjukkan bahwa tingkat infeksi VNN di hatcheri Bali utara terjadi di bulan September sebesar 33,3% dan iridovirus pada bulan Agustus mencapai 18,61%. Sedangkan tingkat prevalensi VNN tertinggi di KJA terjadi pada bulan Oktober mencapai 83,4% dan puncak infeksi iridovirus terjadi di bulan Februari dengan nilai prevalensi sebesar 50,0%. KATA KUNCI: prevalensi; VNN; iridovirus; hatcheri; budidaya laut ABSTRACT: Infection prevalence of viral nervous necrosis (VNN) and iridovirus in hatcheries and mariculture.VNN and iridovirus are viral diseases causing the highest mortality in mariculture. These viruses are able to infect eggs, larvae, juveniles and even marketable size fish. They can cause 80% to 100% mortality in just two weeks. Larvae or fingerlings in small or big scale hatcheries in Northern Bali were frequently infected by VNN or Iridovirus. Unfortunately, information about the local disease outbreaks was not well documented. The aim of this research was to collect data and information about the infection of these viruses in hatcheries and floating net cage mariculture in Northern Bali during 2017. Sampling was conducted in February, May, August, and October, 2017. In addition to the primary data from the field activities, disease infection secondary dataset from the fish farmers who analyzed their infected fish in our laboratory were also used. The identification of VNN infection was performed following IQPlus method while Iridovirus was tested using the conventional PCR method with specific primers. The parameters observed were the VNN and Iridovirus prevalence in each hatchery and floating net cage. Water quality parameters were measured in situ such as tempera...

ABSTRACT-Fingerling humpback grouperCromileptes altivelis, experimentally infected with a betanodavirus (RGNNV genotype), were kept at 27∞C, 31∞C or 35∞C for 14 days. The numbers of dead fish in ten fish at each water temperature were five at 27∞C, two at 31∞C and one at 35∞C. The coat protein gene of the virus was detected by RT-PCR from four survivors at 27∞C, two survivors at 31∞C, but not from survivors at 35∞C. Histopathologically, vacuolation in the retinal tissues was observed in three survivors at 27∞C, but not in survivors at 31∞C or 35∞C. These results suggest that high water temperature inhibits the viral proliferation in fish.

Infeksi trematoda monogenea: Pseudorhabdosynochus sp. dapat menyebabkan kematian massal pada ikan kerapu. Prevalensi infeksi trematoda ini mencapai 100%, namun intensitasnya hingga menimbulkan gejala klinis dan kematian ikan belum diketahui. Tujuan dari penelitian ini adalah untuk mengetahui intensitas parasit insang (Pseudorhabdosynochus sp.) pada ikan kerapu hibrida “cantik” melalui infeksi buatan. Ikan uji direndam dalam air tawar dengan 100 mg/L formalin selama satu jam sebelum digunakan. Infeksi buatan dilakukan melalui (A) kohabitasi antara ikan sehat dengan ikan sakit dan (B) penempelan potongan lamella insang ikan yang terinfeksi parasit ke lamella insang ikan sehat. Pada perlakuan (A) sebanyak lima ekor ikan uji dipelihara bersama dengan dua ekor ikan sakit selama 3-4 hari, sedangkan perlakuan (B) penempelan lamella insang ikan sakit (1 g lamella insang/ikan) dilakukan pada lima ekor ikan uji selama lima menit. Masing-masing perlakuan diulang tiga kali. Pada Kontrol kepadatan ikan uji sehat sebanyak enam ekor dan lima ekor. Wadah yang digunakan berupa bak plastik volume 100 L. Pengamatan intensitas parasit dan telurnya pada setiap lamella insang bagian kanan dan kiri dari lima ekor ikan uji dilakukan selama tiga minggu dengan interval waktu satu minggu. Hasil pengamatan menunjukkan bahwa kohabitasi antara ikan sehat dan ikan sakit menyebabkan intensitas parasit Pseudorhabdosynochus sp. dan telurnya lebih tinggi dibandingkan dengan penempelan lamella insang. Pada kontrol, Pseudorhabdosynochus sp. maupun telurnya tidak ditemukan selama tiga minggu pemeliharaan. Hasil ini menunjukkan penyebaran Pseudorhabdosynochus sp. dari ikan sakit ke ikan sehat lebih cepat dibandingkan dengan penempelan dari lamella insang ikan sakit.Monogenetic trematode (Pseudorhabdosynochus sp.) infection often leads to mass mortality in groupers, with prevalency reaching 100%. However, the intensity of this parasite to infect grouper fish has yet to be reported. The purpose of this research was to study the intensity of Pseudorhabdosynochus sp. in hybrid grouper “cantik” through experimental infection. The test fish were soaked with 100 mg/L of formalin in fresh water before used. The experimental infections were performed through: (A) cohabitation between healthy fish with sick fish and (B) infection with attached of gills lamella of sick fish to gill lamella of healthy fish. In treatment (A), a total of five test fish were cohabited with two sick fish for 3-4 days, while in treatment (B), attachment of gills lamella (1 g/fish) was done on five test fish for five minutes. Each treatment was repeated for three times. Six and five test fish were maintened as controls. The containers used were 100 L plastic tanks volume. Observation of intensity of the parasite infection and its egg production in each lamella along the right and left gills of five fish were conducted for three weeks with one week intervals. The result showed that the cohabitation between healthy and sick fish caused an increase in total of Pseudorhabdosynochus sp. and its eggs compared with the attachment of chopped-gills. In the control group, Pseudorhabdosynochus sp. and its eggs were not found for three weeks. These results indicate the spread of Pseudorhabdosynochus sp. from the sick fish to the healthy is fish faster than the attachment of gill lamella from the sick fish.