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Aim of the study: Vibrio harveyi bacteria are affecting shrimps during grow-out practices. The application of chemicals to control V. harveyi has resulted in antibiotic‐resistance among bacteria. An extract of the leaves of Rhizophora mucronata was tested to control the growth and virulences of V. harveyi. Area of study: This study was conducted in the Crustacean Culture Division of ICAR-CIBA, Chennai city, Tamil Nadu State, India. Material and methods: R. mucronata plants were collected from the Pitchavaram area, and the leaves contents extracted. The resultant extract was prepared and tested against the growth of V. harveyi and its virulence factors. The various functional compounds of R. mucronata were screened and volatile compounds were analyzed. Main results: When R. mucronata extract was treated against V. harveyi (350 µg/mL) an inhibitory zone of 14 ± 0.1 mm was observed. At 300 µg/mL, the extract was found to be active in decreasing the luciferase to a maximum of 76 counts per second in 30 days and a similar level of bioluminescence was reduced in 15 days. During, shrimp larviculture a reduction in the cumulative percent of mortality 15.70% (p

This study was undertaken to investigate the cause of mortality in the captive stock of silver moony Monodactylus argenteus. The fishes showed severe infection of dinoflagellate protozoan Amyloodinium sp. (Blastodinida, Oodiniaceae) on gills and skin with complete mortality of the stock within a week. Histopathological changes were evident in the gill tissues with severe lamellar epithelial cell hyperplasia and lamellar fusions with the presence of trophonts of Amyloodinium sp. Scanning electron microscopy (SEM) also revealed trophonts of Amyloodinium sp. of varying sizes in groups consisting of 3 to 5 trophonts tightly attached to gill lamellae. Source water contaminated with the tiny infectious form of the parasite (dinospores) favoured by higher salinity and low water temperature in the rearing tank could be the triggering factor for the spurt of infections. Proper quarantine and biosecurity protocols to prevent the potential sources of water-borne infection sources are likely to be far more effective than treatment. Keywords: Amyloodiniosis, Amyloodinium sp., Histopathology, Monodactylus argenteus, Scanning electron microscopy, Silver moony, Trophonts

Viral encephalopathy and retinopathy otherwise known as viral nervous necrosis (VNN) is a neuropathological condition affecting more than 50 fish species worldwide, mostly marine. Different PCR protocols with specific primers were reported from many countries for confirmation of VNN in fishes. In the present study, two pairs of primers were designed and evaluated for the diagnosis of clinical and subclinical cases of infections from field. These primers designated as BARL-F1/BARL-R1 amplified a 902 bp product in the variable region (T4) of the coat protein gene by first step PCR. Nested PCR primers BARL-F2/BARL-R2 amplified a fragment of 313 bp. The results were comparable with other commonly used primer sets such as F2/R3 and RG668f/RG919r primers. These new primers could detect betanodavirus in standard reference samples containing low, moderate and high viral load. Known positive and negative control samples of fish also revealed a predictive value of 100 % by RT-PCR diagnosis.

White spot syndrome virus (WSSV) replicates rapidly, can be extremely pathogenic and is a common cause of mass mortality in cultured shrimp. Variable number tandem repeat (VNTR) sequences present in the open reading frame (ORF)94, ORF125 and ORF75 regions of the WSSV genome have been used widely as genetic markers in epidemiological studies. However, reports that VNTRs might evolve rapidly following even a single transmission through penaeid shrimp or other crustacean hosts have created confusion as to how VNTR data is interpreted. To examine VNTR stability again, 2 WSSV strains (PmTN4RU and LvAP11RU) with differing ORF94 tandem repeat numbers and slight differences in apparent virulence were passaged sequentially 6 times through black tiger shrimp Penaeus monodon, Indian white shrimp Feneropenaeus indicus or Pacific white leg shrimp Litopenaeus vannamei. PCR analyses to genotype the ORF94, ORF125 and ORF75 VNTRs did not identify any differences from either of the 2 parental WSSV strains after multiple passages through any of the shrimp species. These data were confirmed by sequence analysis and indicate that the stability of the genome regions containing these VNTRs is quite high at least for the WSSV strains, hosts and number of passages examined and that the VNTR sequences thus represent useful genetic markers for studying WSSV epidemiology.

Jagadeesan, V.; Ezhil Praveena, P.; Otta, S.K., and Jithendran, K.P., 2019. Classical runt deformity syndrome cases in farmed Penaeus vannamei along the east coast of India. In: Jithendran...

We studied the natural progression of viral nerve necrosis (VNN) in larvae of Asian seabass Lates calcarifer Bloch from 0 to 40 days post-hatch (dph). The hatchlings were reared in the vicinity of a confirmed nodavirus-affected older batch. Using light and electron microscopy (EM), we made a sequential analysis of histopathological manifestations in nerve tissue and other organs. There were no changes from the day of hatching until 4 dph. Larvae at 4 dph had viral particles in the intramuscular spaces underlying the skin, but the nerve cells of the brain were normal. The first signs of necrosis of the brain cells were observed at 6 dph. EM observations revealed characteristic membrane-bound viral particles measuring 30 nm in the cytoplasm of nerve cells of the brain, spinal cord and retina. Histological samples of fry examined when group mortalities reached 20 to 35% revealed highly vacuolated brains, empty nerve cell cytoplasm and viral particles in the intercellular spaces. Viral particles occurred extensively in the intramuscular spaces and the epidermal layers. These observations were corroborated by positive immunostaining of the virus-rich intramuscular spaces. EM studies also revealed progressive necrotic changes in the cells harboring the virus. Results emphasize the need to maintain hygiene in the hatchery environment and to develop strategies for prevention of disease spread among cohabiting seabass and other susceptible fish larvae. Intramuscular localization of the nodavirus in both preclinical healthy-looking and post-clinical moribund larvae suggests that virus neutralization strategies during larval development could be effective in controlling VNN-associated mortalities.

A probable vertical mode of piscine nodavirus transmission is reported in the present investigation based on a case of nodavirus associated larval mortalities in hatchery produced Asian sea bass. Polyclonal rabbit anti-SJNNV antibodies (SGWak97) detected the viral antigens in the tissue sections from the eggs and the larvae at different time intervals from − 1 to 42 days post hatch (dph). Immunopositive ovarian connective tissue associated with the oocytes along with the progressive localization of the viral antigens in the brain, spinal cord, liver, stomach and dermal musculature during the larval development indicates a probable vertical transmission of nodavirus in the Asian sea bass. The surviving larger larvae, from the batch suffering mass mortalities, produced very intense immunofluorescent positivity in the liver, stomach and dermal musculature. Results of this investigation demonstrating a possibility of vertical transmission of the nodavirus emphasize the need for screening of eggs and larvae for evolving suitable preventive and prophylactic health management strategies.

Histopathology of Y-organ (moulting gland) in Indian white shrimp Fenneropenaeus indicus was studied after challenging the shrimp with virulent white spot syndrome virus (WSSV). Histopathological investigation on the Y-organ collected from moribund shrimps revealed the presence of intranuclear basophilic inclusions, characteristic of WSSV. More than 70% of the Y-organ cells were infected, suggesting the degenerated state of the organ. The cellular integrity of the Y-organ was completely destroyed by the WSSV. Further, Y-organ tissue samples collected from all the 16 experimental shrimp were positive by one-step polymerase chain reaction (PCR), confirming severe WSSV infection. The infected Y-organ in F. indicus with majority of the organ cells observed in the lysed condition suggests a physiological dysfunction of the organ. In uninfected and healthy controls, the lobulated Y-organ showed closely packed normal cells with prominent nuclei and sparse cytoplasm. Physiological implication of a degenerated Y-organ in the moulting and reproduction of the penaeid shrimp is discussed.

Pacific white shrimp, Litopenaeus vannamei has been introduced recently for culture practice in India. Though SPF stocks are imported for larval production and thereafter culture practice, these are prone to infection with the existing viruses in the environment. Here we report mortality of L.vannamei in several farms in India with minimum biosecurity. The shrimp were harvested early within 50–72 days of culture due to the onset of disease and consequent mortality. As per the analysis carried out, the shrimp were infected with two virus, white spot syndrome virus (WSSV) and infectious hypodermal and hematopoietic necrosis virus (IHHNV). About 80 % of the samples collected had either or both of the viruses. A majority of these samples (60 %) had dual infection with WSSV and IHHNV. Infection of shrimp with WSSV and IHHNV could be detected both by PCR and histopathology. Some of the samples had either exclusively WSSV infection or IHHNV infection and were also harvested before the completion of the required culture period. All the samples analyzed were negative for taura syndrome virus, yellow head virus and infectious myonecrosis virus. While it is difficult to point out the exact etiological agent as the cause of mortality, strict biosecurity measures are advisable for the continuity of L. vannamei culture in India.

[EN] Coccidiosis causad by Eimeria species, is a majar parasitic disease of rabbits and is responsible for a high incidence of morbidity and mortalitv. The incidence of th1s disease in EuroP.ean countries in 21-60% and in India 13-64%. In commercially rearad rabbits; coccidiosis occurs .in a subclinical form witti growth retardation and alterad feed conversion. The disease occurs in two forms, hepatic and intestinal, the latter being more common than the formar. Presently, the control of rabbit coccidiosis relies almost entirely on chemical coccidiostats. However, extensiva use of such arugs in commercial rabbitries has already started creating problems of drug resistance. In view of the limitations of chemotherapy, it is imperativa to develop immunoprophylactic measures against rabbit coccidiosis. These incluae development of live-attenuated and recombinant vaccines against the parasite., [FR] La coccidíose provoquée par des esp_eces du genre Emeiria est la principafe maladie parasitaire affectant le lapin. Elle est respqnssble de la morb1dité et de la mortalité a fréquence élevée. Dans les pays européens, son incidence est de 21 a 60% dans les troupeaux, ene est de 13 a 64% en lnde. Dans les élevages commerciaux de lapins la coccidiose se manifeste sous fonne subc/inique p_rovoquant des retareis de croissance et une réduction de l'effícacité alimentaire. Cette maladie se manifeste sous deux formes, hépatique et intestina/e, la seconde étant plus fréquente que la premíere. Actuellement le contr6/e de la coccidiose chez le lapín est presque exclusivement basé sur l'emploí de coccidiostats chim1ques. Cependant l'usage intensif des ces médicaments commence a créer des problemes de résistance aux anticoccidiens. Afín de limtter la chimíothérapie 11 devient ímpératif de déve/opper des mesures ímmunoprophylactíques pour lutter contre la coccidiose. Celles-ci íncluent le développement de líg_nées atténuées et de vaccíns recombínants utiltsables contre Je parasite.

Cysticercus fasciolaris, the larval form of Taenia taeniaformis is commonly encountered in rodents most often in mice and rats through contaminated feed and bedding materials. The infection is asymptomatic and is considered harmless, but its presence in the laboratory mice/rats could lead to misinterpretation of results for biological experiments. The course of infection and pathogenesis of induced C. fasciolaris was studied in Swiss albino mice. The number of established cysts were not significantly different during the course of infection. The mean diameter of the cysts and the metacestode were significantly different during the course of infection reaching a maximum size of 8.1 +/- 2.2 mm and 80.4 +/- 20.2 mm, respectively on 45 DPI. Histopathologically, on 15 DPI, the duodenum of the affected mice revealed cross sections of early larval stage of C. fasciolaris. On 30 and 45 DPI, the liver showed tract of migration of C. fasciolaris larvae with a thick zone of inflammatory reaction and encapsulation against mature larvae in liver. The routine spontaneous Cystucercus infection is clinically asymptomatic in these animals and is considered harmless. The present experimental infection also followed the same course resulting only in asymptomatic colonisation of the parasites.

The classification of betanodavirus into four species was reviewed including newer and well-characterised isolates. Six major clusters were identified, four of which were similar to the classic species. Two single isolate clusters were worth consideration as new species. Betanodaviruses are small (37 nm average) icosahedral viruses with two positive-stranded non-polyadenylated RNAs as its genome. RNA1 (3.1 kb) codes for the viral RNA-dependent RNA polymerase (protein A), while RNA2 (1.4 kb) codes for the coat protein [16]. A subgenomic RNA3 synthesized from RNA1 during early viral replication codes for protein B2 [17], which functions against the host RNA interference system [3, 8]. These viruses cause viral nervous necrosis (VNN) or viral encephalopathy and retinopathy (VER) in fin fishes. They were first identified as picorna-like virus particles [5] and later described as members of the family Nodaviridae [12]. Taxonomically, these viruses belong to the genus Betanodavirus of family Nodaviridae, with four species recognised so far [16] based on similarities in the variable region of the viral coat protein (CP) gene (nt 604-1030) [14]. The currently recognized species are Redspotted grouper nervous necrosis virus (RGNNV), Striped jack nervous necrosis virus (SJNNV), Tiger puffer nervous necrosis virus (TPNNV) and Barfin flounder nervous necrosis virus (BFNNV), with SJNNV as the type species. The preferred temperature ranges of members of these species are 25-30 C, 20-25 C, 20 C and 15-20 C, respectively. Over 40 fish species have been reported to be susceptible to betanodaviruses, and the number is steadily increasing [10, 13]. Since the first description 15 years ago, the taxonomy of betanodavirus has remained more or less the same irrespective of the huge number of virus isolates being reported from different geographical environments and from different fish hosts. Some modifications were proposed to the system [4, 11, 15, 19], but these have been largely restricted to the geographical area of the researcher. The study presented here is an attempt to analyze the global phylogenetic relationships among the viruses by comparing all isolates for which full-length coat protein (CP) gene ORF sequence information is available in the NCBI GenBank database. A short variable region in the CP gene is shown to be sufficient for determining the phylogenetics of these viruses [14], but the full-length CP gene ORF is used in this study to obtain more reliable results. Sequences of the full-length coat protein gene ORF of betanodaviruses were retrieved from the NCBI GenBank database with due care to include members of the species described in Eighth Report of the International Committee on Taxonomy of Viruses [16]. A total of 78 sequences were retrieved from the database. The sequences were labelled with their geographical location of isolation for ease of compilation for analysing the distribution pattern of the isolates included in this study. Betanodaviruses show high temperature specificity [6] and low host specificity [19], and this is expected to be reflected in their geographical distribution. The nucleotide and deduced amino acid sequences were aligned using the MUSCLE program [2] in MEGA software [18]. Neighbour-joining trees were C. P. Binesh (&) Sacred Heart College, Thevara, Cochin 682013, Kerala, India e-mail: bineshkanayi@gmail.com C. Greeshma Department of Life Sciences, Calicut University, Thenjippalam, Malappauram, Kerala, India e-mail: greeshmakongatta@gmail.com 123 Arch Virol (2013) 158:1589–1594 DOI 10.1007/s00705-012-1549-7