Seasonal status of white spot syndrome virus in broodstocks, nauplii and postlarvae of black tiger shrimp (Penaeus monodon) in Bangladesh

Shrimp classification for white spot syndrome detection through enhanced gated recurrent unit-based wild geese migration optimization algorithm

The major dangerous viral infection for cultivated shrimps is WSSV. The virus is extremely dangerous, spreads swiftly, and may result in up to 100% mortality in 3-10 days. The vast wrapped double stranded DNA virus known as WSSV describes a member of the Nimaviridae viral family's species Whispovirus. It impacts a variety of crustacean hosts but predominantly marine shrimp species that are raised for commercial purposes. The entire age groups are affected by the virus, which leads to widespread mortality. Mesodermal and ectodermal tissues, like the lymph nodes, gills, and cuticular epithelium, represents the centres of infection. Complete genome sequencing related to the WSSV strains from Thailand, China, and Taiwan has identified minute genetic variations amongst them. There exist conflicting findings on the causes of WSSV pathogenicity, which involve variations in the size associated with the genome, the count of tandem repeats, and the availability or lack of certain proteins. Hence, this paper plans to perform the shrimp classification for the WSSV on the basis of novel deep learning methodology. Initially, the data is gathered from the farms as well as internet sources. Next, the pre-processing of the gathered shrimp images is accomplished using the LBP technique. These pre-processed images undergo the segmentation process utilizing the TGVFCMS approach. The extraction of the features from these segmented images is performed by the PLDA technique. In the final step, the classification of the shrimp into healthy shrimp and WSSV affected shrimp is done by the EGRU, in which the parameter tuning is accomplished by the wild GMO algorithm with the consideration of accuracy maximization as the major objective function. Performance indicators for accuracy have been compared with those of various conventional methods, and the results show that the methodology is capable of accurately identifying the shrimp WSSV illness.

Molecular identification of white spot syndrome virus (WSSV) and associated risk factors for white spot disease (WSD) prevalence in shrimp (Penaeus monodon) aquaculture in Bangladesh

White spot disease has caused significant economic losses in the shrimp farming industry of Bangladesh over the last two decades. The responsible virus, WSSV, may show severe disease with significant mortality depending on farm management and environmental and seasonal changes. Data on farm management and environmental parameters were collected from the southwest region of Bangladesh in 2018, and WSSV infection was confirmed by the species-specific gene VP28 using conventional PCR, real-time PCR and sequencing. Through bivariate analysis, nine significant risk factors for WSD were identified, viz. farm age, presence of nursery pond, reservoir of PL, weed in farm area, control of weed, stocking density, stocking frequency, ammonia and oxygen concentration. This study detected 46 WSSV-infected shrimp farms by conventional PCR, whereas real-time PCR identified 47 WSSV-positive out of 49 farms. WSSV prevalence was highest in the Khulna region, with 100% positivity in all seasons. WSSV loads ranged from 5.62 × 10⁹ to 2.01 × 10¹⁵ copies/g of shrimp tissue. The VP28 gene sequence confirmed that 15 representative samples were 100% identical to the 2018 WSSV strain of India. The relationships among risk factors, prevalence and severity of disease, and origin of WSSV strains could be impactful for WSD management.

Development and characterization of white spot disease linked microsatellite DNA markers in Penaeus monodon, and their application to determine the population diversity, cluster and structure

Pathogens that are introduced suddenly to natural populations can potentially cause quick changes to the genetics and diversity of the host. In the past three decades, white spot syndrome virus (WSSV) has caused damaging epizootics in Penaeus monodon populations. In this study, we developed WSSV resistance- or susceptibility-linked microsatellite DNA markers, and their effectiveness was validated experimentally. WSSV-resistant marker linked retroelements and genes that may have an important role in WSSV-resistance phenomena were partially identified. Allelic data of 1,694 samples from nine distinct geographic locations in India were revealed that populations from Digha and Kochi were highly dispersed, and also showed higher genetic diversity, higher population diversity, and lower prevalence of disease resistance. A very high level of gene flow was observed within all populations and a very high level of genetic variation was present within populations. Two genetically admixture population clusters were estimated in nature. WSSV-resistance has a significant link with genetic diversity, population cluster and population diversity. Microsatellite marker analysis characterized genetic divergence, diversity and structure among wild populations.