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

Abstract

This study reports the pathogen Perkinsus beihaiensis in oysters of the genus Crassostrea on the coast of the State of Bahia (Brazil), its prevalence, infection intensity and correlation with salinity. Oysters (n = 240) were collected between October and December 2014 at eight sampling stations between latitudes 13°55'S and 15°42'S. The laboratory procedures included macroscopic analysis, histology, culture in Ray's fluid thioglycollate medium (RFTM), Polymerase Chain Reaction (PCR) and DNA sequencing. PCR and sequencing have been used for the genetic identification of oysters as well. Two species of oysters have been identified: Crassostrea rhizophorae and C. brasiliana. In both oyster species P. beihaiensis was the only Perkinsus species detected. In C. rhizophorae, the average prevalence was 82.8% by histology and 65.2% by RFTM. In C. brasiliana, the prevalences were 70.5% and 35.7%, respectively. The higher prevalence of P. beihaiensis in C. rhizophorae was probably influenced by salinity, with which was positively correlated (r> 0.8). In both oysters, P. beihaiensis was located mainly in the gastric epithelium. The infection was generally mild or moderate, without apparent harm to the hosts, but in cases of severe infection, there was hemocytical reaction and tissue disorganization. The generally high prevalence in the region suggests that oysters should be monitored with respect to this pathogen, especially in growing areas.Keywords: bivalves, diseases, pathology, salinity. Perkinsus beihaiensis (Perkinsozoa) em ostras do Estado da Bahia ResumoEste estudo relata o patógeno Perkinsus beihaiensis em ostras do gênero Crassostrea no litoral do Estado da Bahia (Brasil), sua prevalência, intensidade de infecção e correlação com a salinidade. As ostras (n = 240) foram coletadas entre outubro e dezembro de 2014 em oito estações amostrais entre as latitudes 13°55'S e 15°42'S. Os procedimentos laboratoriais incluíram análise macroscópica, histologia, cultivo em meio de tioglicolato de Ray (RFTM), reação em cadeia da polimerase (PCR) e sequenciamento de DNA. PCR e sequenciamento foram também utilizados para a identificação genética das ostras. Foram identificadas duas espécies de ostras: Crassostrea rhizophorae e C. brasiliana. Em ambas as espécies, P. beihaiensis foi a única espécie de Perkinsus detectada. Em C. rhizophorae, a prevalência média foi de 82,8% por histologia e de 65,2% por RFTM. Em C. brasiliana, as prevalências foram de 70,5% e 35,7%, respectivamente. A maior prevalência de P. beihaiensis em C. rhizophorae foi provavelmente influenciada pela salinidade, com a qual este apresentou correlação positiva (r>0,8). Em ambas as espécies, P. beihaiensis esteve localizada principalmente no epitélio gástrico. A infecção foi geralmente leve ou moderada, sem danos aparentes aos hospedeiros, mas em casos de infecção severa, houve reação hemocitária e desorganização de tecidos. As prevalências geralmente altas na região sugerem que as ostras devam ser monitoradas com relação a este patógeno, principalmente e...

Perkinsus sp. infecting three important mollusks from Jaguaribe River estuary, Ceará, Brazil

“…In recent years, the prevalence of Perkinsus observed in oysters from different regions of the country has varied considerably and, although the value found in this study (8%) has been lower than that recorded in oysters from that same estuary in 2015 (17.3%) and in oysters from Carnaubeira River in Maranhão (10.6%), the same was higher than the values recorded in oysters from the estuaries of the Rivers Camurupim, in Piauí (5.3%) and Pacoti, in Ceará, in 2009and 2010. In other states of the northeastern region, the prevalence of Perkinsus recorded in the RFTM assays has been higher than the values mentioned above (Luz et al, 2018;Queiroga et al, 2015;Scardua et al, 2017;Silva et al, 2016). In the present study, the infection intensity ranged from very light to light (clams), very light to severe (oysters) and very light to moderate (mussels).…”

“…On the other hand, Perkinsus cells were observed phagocytosed in the tissues of Crassostrea gasar, indicating a defense response of the host (Queiroga et al, 2015). Also, recent studies with oysters from Bahia showed that the animals infected with P. beihaiensis presented hemocytes infiltration and tissue disorganization (Luz & Boehs, 2016;Luz et al, 2018). As can be observed, the effects of infection by this pathogen on the host need to be better understood.…”

“…As observed, 23 animals showed a negative result in qPCR, suggesting the low intensity of Perkinsus cells in the infected tissues or they did not contain cells of the pathogen. Differences in results between diagnostic techniques have been associated with low amount of tissue and low infection intensity (Brandão et al, 2013;Sabry et al, 2009Sabry et al, , 2013 and also the use of different organs in the techniques used for the diagnosis (Luz et al, 2018). In another study, Dantas et al (2016) found different results between the techniques of conventional PCR and qPCR, confirming the greater sensitivity of the latter for detection of Perkinsus sp.…”

“…Since then, other studies have reported the occurrence of Perkinsus sp. in oysters of the genus Crassostrea from several regions (Brandão et al, 2013;Luz et al, 2018;Scardua et al, 2017). It is worth noting the record, in 2016, of the species P. chesapeaki, detected for the first time in South America, infecting oysters from the Jaguaribe River estuary, Ceará (Dantas et al, 2016).…”

Two epizootic Perkinsus spp. events in commercial oyster farms at Santa Catarina, Brazil

“…C. rhizophorae was also reported to be infected by Perkinsus sp. in Bahia State (Brandão et al, ), with P. marinus in Paraíba (da Silva et al, ) and in Ceará (Neto, ) and with P. beihaiensis in Ceará (Sabry et al, ) and in Bahia (Luz, Carvalho, Oliveira, & Boehs, ), and by Perkinsus chesapeaki in Ceará (Neto, ). Perkinsus beihaiensis infection in the clam Anomalocardia brasiliana was also reported in Ceará by Ferreira et al ().…”