First report of Perkinsus beihaiensis in Crassostrea madrasensis from the Indian subcontinent

Abstract

Protozoan parasites of the genus Perkinsus are considered important pathogens responsible for mass mortalities in many wild and farmed bivalve populations. The present study was initiated to screen populations of the Indian edible oyster Crassostrea madrasensis, a promising candidate for aquaculture along the Indian coasts, for the presence of Perkinsus spp. The study reports the presence of P. beihaiensis for the first time in C. madrasensis populations from the Indian subcontinent and south Asia. Samples collected from the east and west coasts of India were subjected to Ray's fluid thioglycollate medium (RFTM) culture and histology which indicated the presence of Perkinsus spp. PCR screening of the tissues using specific primers amplified the product specific to the genus Perkinsus. The taxonomic affinities of the parasites were determined by sequencing both internal transcribed spacer (ITS) and actin genes followed by basic local alignment search tool (BLAST) analysis. Analysis based on the ITS sequences showed 98 to 100% identity to Perkinsus spp. (P. beihaiensis and Brazilian Perkinsus sp.). The pairwise genetic distance values and phylogenetic analysis confirmed that 2 of the present samples belonged to the P. beihaiensis clade while the other 4 showed close affinities with the Brazilian Perkinsus sp. clade. The genetic divergence data, close affinity with the Brazilian Perkinsus sp., and co-existence with P. beihaiensis in the same host species in the same habitat show that the remaining 4 samples exhibit some degree of variation from P. beihaiensis. As expected, the sequencing of actin genes did not show any divergence among the samples studied. They probably could be intraspecific variants of P. beihaiensis having a separate lineage in the process of evolution. KEY WORDS: Edible oyster · Crassostrea madrasensis · Protozoan parasite · Perkinsus beihaiensis · Brazilian Perkinsus sp. · Indian subcontinent Resale or republication not permitted without written consent of the publisherDis Aquat Org 98: [209][210][211][212][213][214][215][216][217][218][219][220] 2012 zoospore. Transmission of Perkinsus spp. does not require an intermediate host. In moribund hosts or when cultured in Ray's fluid thioglycollate medium (RFTM), the mature trophozoites transform into hypnospores. In sea water, these hypnospores develop into zoosporangia, undergo zoosporulation and produce infective zoospores. Trophozoites and hypnospores are also infective .Since the introduction of molecular techniques in disease diagnosis, new species belonging to the genus Perkinsus have been described from various molluscan hosts across the world (Dungan & Reece 2006, Moss et al. 2008. Through culture in RFTM, the standard diagnostic method for Perkinsus spp., the parasites can be identified up to the genus level. The broad host range and highly variable and overlapping morphologic and morphometric features of these parasites makes their species-level identification difficult (Goggin & Lester 1995, Perkins 1996, Coss et al. 2001. ...

Growth, mortality and susceptibility of oyster Crassostrea spp. to Perkinsus spp. infection during on growing in northeast Brazil

“…Similar symptoms were observed in C. rhizophorae (SABRY et al, 2009) and C. gasar (QUEIROGA et al, 2015) from Brazil. In contrast, Sanil et al (2012) reported some digestive tubule lesions in Crassostrea madrasensis, but these lesions were not directly associated with P. beihaiensis.…”

Perkinsus beihaiensis (Perkinsozoa) in oysters of Bahia State, Brazil

“…Sequencing demonstrated that this was P. beihaiensis, with 98 to 100% similarity with the sequences available at NCBI, as deposited by Sanil et al (2012) and Sabry et al (2013), to India and the Northeast Brazil, respectively. The obtained sequence was deposited in GenBank with number KX923545.…”

“…The preferred location of P. beihaiensis in the digestive epithelium has been reported in previous studies on the genus Crassostrea (Moss et al, 2008;Sanil et al, 2012;Sabry et al, 2013;Queiroga et al, 2015;Luz and Boehs, 2016). Oysters with severe infection (level 4, Ray's scale) showed disorganization of gastric and intestinal epithelia and were assessed as impaired by the infection.…”

“…In turn, both in the mantle and adductor muscle, as in oysters that had a low level of infection, there was no tissue change. Sanil et al (2012) reported destruction of digestive tubules in some cases of infection by P. beihaiensis. Moss et al (2008) reported epithelial lesions and necrosis in the stomach, intestine and digestive gland.…”

Nematopsis sp. (Apicomplexa: Porosporidae) infection in Crassostrea madrasensis and its associated histopathology

“…Presently the species contributes to about 4000 tonnes to the fast growing bivalve farming sector in India. The rapidly expanding edible oyster farming and its management points to the importance of information on the parasites/pathogens of this species which is presently very limited (Samuel, 1978;Bijukumar, 2001;Sanil et al, 2012;Suja et al, 2014).…”