White Spot Syndrome in Shrimp – Research Findings & Solutions
Understanding & Combating White Spot Syndrome in Shrimp
White Spot Syndrome Virus (WSSV) is one of the most devastating diseases in shrimp aquaculture, causing rapid mortality and severe economic losses. Our latest research provides scientific insights into WSSV detection, transmission pathways, and prevention strategies.
Study Overview
Background
Shrimps of the family Penaeidae belong to the order Decapoda, class Crustacea, and phylum Arthropoda. They have successfully spread across the globe. However, due to their high market demand and widespread consumption in the food industry, commercial production in artificial environments has significantly expanded.
According to the latest statistics from the Food and Agriculture Organization (FAO), global aquaculture production has reached 53 million tons, with Penaeidae shrimp contributing 4.5 million tons (FAO, 2021). One of the main challenges in aquaculture, particularly shrimp farming, is disease management. Pathogen outbreaks impose millions of dollars in losses annually on fish and shrimp farmers (Afsharnasab et al., 2007). Bacterial, viral, and fungal infections pose serious threats to the industry. In the Penaeidae family alone, researchers have identified approximately 20 viral diseases, four bacterial diseases, three fungal diseases, and several parasitic infections (Tapay et al., 1999; Lightner, 2003).
Among these, White Spot Disease (WSD) is one of the most devastating viral infections, often leading to 100% mortality within 3 to 10 days, particularly when combined with environmental stressors such as temperature fluctuations and oxygen depletion (Lightner, 1996). The causative agent, White Spot Syndrome Virus (WSSV), belongs to the family Nimaviridae, genus Whispovirus (Pruder et al., 1995; OIE, 2021). This large, enveloped virus has an elliptical to bacillary shape, measuring approximately 120–150 nm in diameter and 300–350 nm in length. It contains double-stranded DNA with a tail-like appendage at its end (Reitman et al., 1970). The virus is composed of five large and 13 small proteins, with VP28, VP19, and the nucleocapsid VP15 playing key roles in infection (Afsharnasab et al., 2007, 2009; Pazir et al., 2011).
White Spot Disease was first reported between 1992 and 1993 in China’s Fujian and Quanzhou provinces, causing up to 80% losses in shrimp farms
Since the virus responsible for White Spot Disease (WSD) can persist in the environment for extended periods as virions (complete virus particles), the risk of subsequent infections remains high (Lightner, 1996). Unfortunately, no effective treatment or preventive measure has been developed to combat WSD (Pazir et al., 2011). Due to shrimp having a non-specific immune system and lacking memory cells, vaccination is not a viable option. Furthermore, the virus can be transmitted both vertically (from broodstock to postlarvae) and horizontally, further complicating disease control.
In this study, for the first time, SENTINEL X was used to remotely monitor and detect the incidence of infection and respond by sending a therapeutic signal. Using an advanced biological signal recording system, frequencies are converted into digital files, which are then analyzed at a data center. The resulting therapeutic signal is transmitted back to the living organism via a bioresonance transmitting device, facilitating treatment without direct contact.
Given the extensive applications of this technology in medicine, this study aimed to explore its use in the shrimp farming industry. Specifically, the goal was to detect shrimp susceptible to White Spot Virus before infection occurs, thereby preventing rapid disease spread and minimizing losses. Additionally, although it was not the aim of the study, the potential of this technology for treating WSD was assessed.
Study Design
Initial Setup
To evaluate the effects of different SENTINEL X frequencies on the prevention and treatment of White Spot Viral Disease (WSD) in western white shrimp, the study was conducted using six treatment groups, each with three replications, in glass aquariums.
After draining three-quarters of the aquarium tanks and adjusting the salinity to 41 parts per thousand, 20 western white shrimp, each weighing 15–16 grams, were placed in each replication for the different treatments. Prior to transferring the shrimp to the aquariums, their health status was confirmed using the Polymerase Chain Reaction (PCR) molecular method to ensure they were free from White Spot Virus. After placement, the shrimp underwent a five-day adaptation period. Six groups were part of the experiment design.
Following this, each treatment group was monitored via SENTINEL X’s sensors. This data, transmitted digitally via the Internet, was analyzed at the data center to assess the susceptibility of treated shrimp to viral infection and evaluate the effectiveness of their non-specific immune defense system. Based on this analysis, the appropriate treatment frequencies were determined and compiled into an electronic file designed to enhance immune function and resistance to White Spot Virus. The contents of this file were transmitted into the water through SENTINEL X’s transmitter.
This procedure was performed twice, on February 2, 2022, and March 5, 2022. After the treatment period, and following confirmation of an improved immune response, all shrimp were re-tested using the PCR molecular method before being exposed to White Spot Virus to ensure that they remained virus-free.
Infection with WSSV
The study period for this phase lasted 10 days. After one month of storing the shrimp and confirming they were free from White Spot Virus, they were infected with the virus through their food on March 5, 2022.
On the third day post-infection, tissue samples were taken from the swimming leg muscle or dead shrimp in each treatment group. The presence or absence of White Spot Virus in the tissues of the treated shrimp was then examined using the Nested-PCR molecular method .
During this period, the shrimp were fed a concentrated diet three times a day, based on their average weight, at a feeding rate of 3% of their body weight. Additionally, from the time the shrimp were exposed to therapeutic signals until their infection with White Spot Virus, all key water quality parameters were carefully regulated. These included:
Water temperature: 27 ± 1°C
Dissolved oxygen: 5.5–6.5 mg/L
Salinity: 41 ± 0.5 parts per thousand
pH: 7.8–8.2
Water in the tanks was replaced every 2–3 days, depending on quality. Approximately 75–80% of the total tank volume was refreshed using filtered seawater disinfected with sodium hypochlorite.
Figure 3A: Sampling of dead shrimp for the Nested-PCR test
Figure 3B: Infection of Shrimp with White Spot Virus through feed
Stress Indcution
Starting from day three, in order to activate the White Spot Virus, the water temperature in the tanks was gradually reduced from 27°C to 21-22°C by introducing environmental stressors, such as adding ice cubes. At the same time, aeration in the treatment tanks was stopped to further stress the shrimp by reducing the dissolved oxygen levels in the water.
It should be noted that throughout the study, the mortality rate for each treatment group was recorded on designated forms.
The Results
The results, based on the Kaplan-Meier test, indicated that by the fourth day post-infection, 100% of the shrimp in the B3 control group (infected with White Spot Virus without the use of Sentinel X) had perished.
In contrast, in the three Sentinel X-boosted treatment groups (T3, T2, and T1), the shrimp survival rate remained at an average of 98% on the fourth day post-infection.
It is important to note that under normal conditions, farms monitored by Sentinel X implement necessary treatment measures as soon as an infection or disease is detected. However, since this study focused solely on evaluating Sentinel X’s preventive capabilities, its therapeutic functions were not utilized. Monitoring continued until the tenth day post-infection to assess the preventive effects of the system.
It should be noted that the comparisons of the controls B1 and B2 at the end of this study indicate that not only did sentinel X not have any adverse effects on the shrimp, but its survival was also better than under normal conditions, which was about 5%.
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