Antiviral viral compound fromStreptomyces ghanaensislike strain against white spot syndrome virus (WSSV) of shrimp

Abstract

35Actinomycetes isolates collected from different environments were screened for 36 antiviral activity against WSSV. One isolate designated as CAHSH-2 showed antiviral 37 activity against WSSV at the concentration of 0.2 mg per shrimp. The laboratory trial of 38 determining antiviral activity of ethyl acetate extract (EtOAcE) of CAHSH-2 against WSSV 39 was carried out 21 times since 2014. CAHSH-2 isolate which showed antiviral activity was 40 characterized and identified as Streptomyces ghanaensis like strain. Among the five fractions 41 obtained from EtOAcE of potential actinomycetes isolate, F1 was found to have strong 42 antiviral activity. The F1A and F1B sub-fractions from F1 fraction were subjected to GC-MS, 43 FTIR, 1 H and 13 C NMR analyses and, the compounds identified were di-n-octyl phthalate and 44 bis (2-methylheptyl) phthalate, respectively. Among these compounds, di-n-octyl phthalate 45 showed strong antiviral activity against WSSV. Molecular docking studies revealed that di-n-46 octyl phthalate was found to have high binding affinity with VP26 and VP28 proteins of 47 WSSV, whereas the bis (2-methylheptyl) phthalate showed low binding affinity with VP26 48 and VP28. The antiviral activity of EtOAcE of actinomycetes against WSSV was confirmed 49 by PCR, RT-PCR, Western blot and ELISA. The EA extract of active isolate was found to be 50 non-toxic to Artemia, post-larvae and adult Litopenaeus vannamei. 51 Importance 52 53White spot syndrome virus (WSSV) is an important shrimp viral pathogen and 54 responsible for huge economic loss to shrimp culture industry worldwide including India. The 55 global loss due to WSSV has been estimated about USD 10 billion and the loss continues at 56 the same extent even now. Various strategies have been followed to prevent or control 57 diseases of aquatic animals. In spite of various preventive and control strategies, WSSV has 58 been still persisting for more than two decades. No control strategies have so far been evolved 59 to put a break to WSSV. In this situation, an attempt was made in the present work to screen 60 some actinomycetes isolates for antiviral activity against WSSV. Among these isolates, one 61 isolate identified as Streptomyces ghanaensis like isolate CAHSH-2 showed activity against 62 WSSV. This article gives the information about the antiviral compound against WSSV and 63 the mechanism of viral inhibition. 64 65 66

Isolation and Characterization of a Novel Actinomycete Isolated from Marine Sediments and Its Antibacterial Activity against Fish Pathogens

“…In the present study, B. fluminensis gave positive results for starch, casein and gelatin hydrolysis, citrate and urease, while negative results were obtained for methyl-red, Voges–Proskauer and indole tests. Rajkumar et al [ 33 ] isolated actinomycetes from different environments. They reported that the isolated Actinomycetes showed negative Indole, MR and VP.…”

“…In the present work, we observed that they were able to tolerate up to 7% salt concentration. Rajkumar et al [ 33 ] also reported that the Actinomycetes were able to survive in 9% NaCl. In the present study, equally similar biochemical and physiological characteristics, such as NaCl tolerance (salinity), temperature tolerance, as well as biochemical characteristics of Actinomycetes, were reported.…”

“…The kit consisted of 11 sugars, including Melezitose, Xylitol, Cellobiose, D-Arabinose, Sorbose, Rhamnose, alpha-Methyl-D-Mannoside, Malonate, Esculin, Citrate, O-Nitrophenyl-β-D-galactopyranoside (ONPG) and one control. Parts C of the wells in the kit were inoculated similarly to the Actinomycetes and incubated at 30 °C for 7–14 days [ 33 ].…”

“…Then, it was kept in a shaker for 48 h, after which it was removed and the solvent layer collected. The concentration of the solvent layer was carried out using a rotary evaporator to obtain the crude metabolites [ 33 ]. As per some earlier reports, studies were conducted using various solvents, which gave better results in the extraction of bioactive compounds from the CFS of Actinomycetes .…”

Actinobacteria and their bioactive molecules for anti‐WSSV activity: A mini review

“…The antiviral properties of the methanol extract of the isolates were found to be lesser effective when compared to the whole broth and also these extracts (L27, L35, L45, L56 and B451) showed 40% survival. Another study reported, 64 actinobacterial isolates collected by from different environments, a specific strain designated as CAHSH–2 exhibited potent anti‐WSSV activity at low concentration (0.2 mg) per shrimp (Rajkumar et al., 2018). Antiviral activity of the extracts was tested in marine shrimp, Litopeneaus vannamei infected with WSSV was confirmed by RT‐PCR, Western blot analysis and ELISA.…”