Detection of Laem-Singh virus in cultured Penaeus monodon shrimp from several sites in the Indo-Pacific region.

Laem-Singh virus (LSNV) is a positive-sense single-stranded RNA (ssRNA) virus that was recently identified in Penaeus monodon shrimp in Thailand displaying signs of slow growth syndrome. A total of 326 shrimp collected between 1998 and 2007 from countries in the Indo-Pacific region were tested by RT-PCR for evidence of LSNV infection. The samples comprised batches of whole postlarvae, and lymphoid organ, gill, muscle or pleopod tissue of juvenile, subadult and adult shrimp.

Homologous genetic recombination in the yellow head complex of nidoviruses infecting Penaeus monodon shrimp.

Yellow head virus (YHV) is a highly virulent pathogen of Penaeus monodon shrimp. It is one of six known genotypes in the yellow head complex of nidoviruses which also includes mildly pathogenic gill-associated virus (GAV, genotype 2) and four other genotypes (genotypes 3-6) that have been detected only in healthy shrimp. In this study, comparative phylogenetic analyses conducted on replicase- (ORF1b) and glycoprotein- (ORF3) gene amplicons identified 10 putative natural recombinants amongst 28 viruses representing all six genotypes from across the Indo-Pacific region.

A virulent isolate of yellow head nidovirus contains a deformed envelope glycoprotein gp116.

Yellow head virus (YHV) is a highly virulent pathogen of penaeid shrimp. An isolate obtained from Penaeus vannamei during a yellow head disease outbreak in February 2006 in Ratchaburi Province, Thailand was purified following passage in experimentally infected shrimp. SDS-PAGE of purified virions indicated that envelope glycoprotein gp116 in the Ratchaburi/2006 isolate was smaller and relatively less abundant than in the Chachoengsao/1998 YHV reference strain.

RNA transcription analysis and completion of the genome sequence of yellow head nidovirus.

Yellow head virus (YHV) is a pathogen of the black tiger shrimp (Penaeus monodon) and, with gill-associated virus (GAV), is one of two known invertebrate nidoviruses. We describe sequences of the large replicase gene (ORF1a) and 5'- and 3'-terminal UTRs, completing the 26,662 nt sequence of the YHV genome. ORF1a (12,219 nt) encodes a approximately 462,662 Da polypeptide containing a putative 3C-like protease and a putative papain-like protease with the canonical C/H catalytic dyad and alpha+beta fold.

Structural and antigenic analysis of the yellow head virus nucleocapsid protein p20.

Yellow head virus (YHV) is an invertebrate nidovirus that is highly pathogenic for marine shrimp. Nucleotide sequence analysis indicated that the YHV ORF2 gene encodes a basic protein (pI = 9.9) of 146 amino acids with a predicted molecular weight of 16,325.

The gene encoding the nucleocapsid protein of Gill-associated nidovirus of Penaeus monodon prawns is located upstream of the glycoprotein gene.

The ORF2 gene of Gill-associated virus (GAV) of Penaeus monodon prawns resides 93 nucleotides downstream of the ORF1a-ORF1b gene and encodes a 144-amino-acid hydrophilic polypeptide (15,998 Da; pI, 9.75) containing 20 basic (14%) and 13 acidic (9%) residues and 19 prolines (13%). Antiserum to a synthetic ORF2 peptide or an Escherichia coli-expressed glutathione S-transferase-ORF2 fusion protein detected a 20-kDa protein in infected lymphoid organ and gill tissues in Western blots.

Identification and analysis of gp116 and gp64 structural glycoproteins of yellow head nidovirus of Penaeus monodon shrimp.

Yellow head virus (YHV) is a major agent of disease in farmed penaeid shrimp. YHV virions purified from infected shrimp contain three major structural proteins of molecular mass 116 kDa (gp116), 64 kDa (gp64) and 20 kDa (p20). Two different staining methods indicated that the gp116 and gp64 proteins are glycosylated.

Complete ORF1b-gene sequence indicates yellow head virus is an invertebrate nidovirus.

We report the sequence of an 8503 nucleotide (nt) region of the genome of yellow head virus (YHV) encompassing the open reading frame (ORF) 1b gene. Comparison with the sequence of Australian gill-associated virus (GAV) indicated that the region, comprising approximately 30% of the YHV genome, commences 268 nt upstream of the putative ORF1a termination codon and continues through ORF1b to a site 30 nt downstream of the ORF2 initiation codon. YHV ORF1a and ORF1b overlap by 37 nt.