New genetic recombination in hypervariable regions of the white spot syndrome virus isolated from Litopenaeus vannamei (Boone) in northwest Mexico

Abstract

The white spot syndrome virus (WSSV) is a pathogen of great concern to the worldwide shrimp culture. In comparative studies on the WSSV genome, regions such as the open reading frame (ORF) 14–15 and ORF 23–24, prone to deletions and recombination, had been useful to study the evolutive relationships among viral strains. When looking for the WSSV strains infecting Litopenaeus vannamei (Boone) in northwest Mexico, we found evidence of a genetic similarity in ORF 14–15 to a strain from India and a recombination involving ORFs 78, 79 and 80. Two genotypes were found involving the insertion of a 265 base‐pair segment of ORF 108 into ORF 78 with inversions and deletions within ORFs 78, 79 and 80. The WSSV has an Asian origin and the mutations found could be an adaptation strategy to infect L. vannamei and other crustacean species of the American continent.

Genetic variation of white spot syndrome virus (WSSV) in Pacific white shrimp Litopenaeus vannamei (Boone 1931) culture of Thailand

“…Pradeep, Shekar, Karunasagar and Karunasagar () demonstrated that Indian WSSV isolates were closely related to Thai isolates, suggesting WSSV may have been introduced to India from Thailand. Likewise, WSSV isolates from Mexico collected during 2000–2005 showed similarity in the VR14/15 region with isolates from India (Ramos‐Paredes, Grijalva‐Chon, Rosa‐Vélez & Enríquez‐Paredes, ). On the contrary, VNTR have been used to study WSSV epidemiology in small scales, such as farm‐ or pond‐level and for tracing movements between infected populations because these regions have high variation (González‐Galaviz, Rodriguez‐Anaya, Molina‐Garza, Ibarra‐Gámez & Galaviz‐Silva, ; Pradeep, Shekar, Gudkovs, Karunasagar & Karunasagar, ).…”

“…The 6031 bp deletion in VR14/15 region were also previously reported in WSSV from Thailand (WSSV‐TH‐S, 1996), the Philippines (WSSV‐PHI, 1999), Indonesia (WSSV‐INDO, 2008) (Zwart et al., ) and Vietnam (WSSV‐VN, 2003–2004) (Dieu et al., ). The unsuccessful in VR23/24 amplification were noticed in some studies, isolates from Vietnam (Dieu et al., ), India (Pradeep et al., ) and Mexico (Ramos‐Paredes et al., ) while it was proposed that the deletion of VR23/24 region extends beyond the coverage of primers designed from Asian WSSV sequence.…”

Virulence and genotypes of white spot syndrome virus infecting Pacific white shrimp Litopenaeus vannamei in north‐western Mexico

“…Briefly, DNA extraction, quality checking and concentration estimation were performed as described previously (Ramos‐Paredes et al . ). The Vp28 gene PCR (974 bp amplicon) used primers WO001‐F and WO001‐R designed using the Primer3 software (Table ).…”

“…The seminested PCR (694‐bp amplicon) used primer WO001‐F in combination with WSSVP28‐R1 (Ramos‐Paredes et al . ) and 1 μL of the first PCR was used as template. PCR thermal cycling conditions were as described previously (Ramos‐Paredes et al .…”

Antibacterial effect of biosynthesized silver nanoparticles in Pacific white shrimp Litopenaeus vannamei (Boone) infected with necrotizing hepatopancreatitis bacterium (NHP B)

“…The oligos WSSVVP28-F1: 5'-CTCGCTTGCCAATTGTCCTGT TA-3' and WSSVVP28-R1: 5'-ATTTCCACCGGC GGTAGCTGC-3' reported by Ramos-Paredes et al (2012) were used, as well as thermal cycling conditions as recommended by these authors. A negative control without DNA was used in all cases.…”