Praveen Rai

Detection of class 1 integrons in Salmonella Weltevreden and silent antibiotic resistance genes in some seafood‐associated nontyphoidal isolates of Salmonella in south‐west coast of India

Aims:  To study the antibiogram of 40 seafood isolates of Salmonella and use of PCR to detect the presence of integrons and genes coding for antibiotic resistance.

Complete nucleic acid sequence of Penaeus monodon densovirus (PmDNV) from India

The complete nucleic acid sequence of the Penaeus monodon densovirus (PmDNV) from India was characterized. Analysis of the whole genome, consisting of 6310 bp revealed the presence of three open reading frames (ORFs), comprising 1281 bp, 1734 bp and 2460 bp, respectively. The complete genome and amino acid sequences of three proteins viz., NS1, NS2 and VP were compared with PmDNV from Thailand, PmergDNV from Australia and other partial sequences in GenBank, respectively. Highest nucleotide similarity was observed with the Thai strain (88%), while 33, 32 and 91 amino acid substitutions were observed in the NS2, NS1 and VP, respectively. Phylogenetic analysis of shrimp, insect and vertebrate parvovirus sequences revealed that the Indian PmDNV is more closely related to Thai isolates than all other parvoviruses reported so far.

Complete nucleic acid sequence of Penaeus stylirostris densovirus (PstDNV) from India

Infectious hypodermal and hematopoietic necrosis virus (IHHNV) of shrimp, recently been classified as Penaeus stylirostris densovirus (PstDNV). The complete nucleic acid sequence of PstDNV from India was obtained by cloning and sequencing of different DNA fragment of the virus. The genome organisation of PstDNV revealed that there were three major coding domains: a left ORF (NS1) of 2001 bp, a mid ORF (NS2) of 1092 bp and a right ORF (VP) of 990 bp. The complete genome and amino acid sequences of three proteins viz., NS1, NS2 and VP were compared with the genomes of the virus reported from Hawaii, China and Mexico and with partial sequence available from isolates from different regions. The phylogenetic analysis of shrimp, insect and vertebrate parvovirus sequences showed that the Indian PstDNV isolate is phylogenetically more closely related to one of the three isolates from Taiwan (AY355307), and two isolates (AY362547 and AY102034) from Thailand.

Presence of T3SS2β genes in trh⁺ Vibrio parahaemolyticus isolated from seafood harvested along Mangalore coast, India.

Vibrio parahaemolyticus is a seafood‐borne pathogen autochthonous to the marine and estuarine ecosystem, responsible for gastroenteritis when contaminated raw seafood is consumed. The pathogenicity has been associated with thermostable direct haemolysin (TDH) and TDH‐related haemolysin (TRH). Of late, the presence of T3SS2α and T3SS2β gene clusters has been well documented in clinical isolates of Vibrio parahaemolyticus and known to play an essential role in pathogenesis. However, reports on the presence of T3SSβ genes in V. parahaemolyticus isolated from the seafood and/or environmental samples are scanty. In this study, we have identified and analysed the distribution of the T3SS2β genes in V. parahaemolyticus isolated from seafood harvested along southwest coast of India. Results showed that T3SS2β genes are solely associated with trh+ and tdh+/trh+ strains of V. parahaemolyticus. Reverse transcriptase PCR (RT‐PCR) showed that the T3SS2β genes identified in trh+ V. parahaemolyticus were transcriptionally active. To our knowledge, this study appears to be the first description on the presence of T3SS2β‐positive V. parahaemolyticus isolated from seafood in India. The study of T3SS2 along with other virulence factors will help in better understanding of the risk of seafood‐borne illness due to V. parahaemolyticus.

Molecular Biology and Epidemiology of Hepatopancreatic parvovirus of Penaeid Shrimp

Hepatopancreatic parvovirus (HPV) is one of the major shrimp parvovirus which is known to cause slow growth in penaeid shrimps. HPV has been found in wild and cultured penaeid shrimps throughout the world and there is high genetic variation among the different geographic isolates/host species. Given its high prevalence, wide distribution and ability to cause considerable economic loss in shrimp aquaculture industry, HPV deserves more attention than it has received. Till date, a total of four complete genome sequences of HPV have been reported in addition to a large number of partial sequences. HPV infection is seldom observed alone in epizootics and has occurred in multiple infections with other more pathogenic viruses and in most cases, heavy infections result in no visible inflammatory response. A great deal of information has accumulated in recent years on the clinical signs, geographical distribution, transmission and genetic diversity of HPV infection in shrimp aquaculture. However, the mechanism by which HPV enters the shrimp tissues and pathogenesis of virus is still unknown. To date, no effective prophylactic measures are available to reduce the infection in shrimps. To control and prevent HPV infection, considerable research efforts are on. This review provides information on current knowledge on HPV infection in penaeid shrimp aquaculture.

Draft Genome Sequence of trh+ Vibrio parahaemolyticus VP-49, Isolated from Seafood Harvested along the Mangalore Coast, India

ABSTRACT Vibrio parahaemolyticus is a seafood-borne pathogen autochthonous to the marine and estuarine ecosystem, which is responsible for gastroenteritis due to the consumption of contaminated raw seafood. Here, we report the draft genome sequence of V. parahaemolyticus VP-49, isolated from seafood, to identify the different virulence attributes and to study the mechanisms that enhance its environmental fitness.

Simultaneous detection of Salmonella pathogenicity island 2 and its antibiotic resistance genes from seafood.

Salmonella enterica serovars are virulent pathogens of humans and animals with many strains possessing multiple drug resistance traits. They have been found to carry resistance to ampicillin, chloramphenicol, florfenicol, streptomycin, sulfonamides, and tetracycline (ACSSuT-resistant). A rapid and sensitive multiplex PCR (mPCR)-based assay was developed for the detection of Salmonella serovars from seafood. Six sets of primers which are one primer pair targeting Salmonella specific gene invA (284 bp), two Salmonella pathogenicity island 2 (SPI-2) genes ssaT (780 bp) and sseF (888 bp) and three antibiotic resistance genes floR (198 bp), sul1 (425 bp), tetG (550 bp) were used for the study. The specificity and sensitivity of the assay were tested by spiking shrimp/fish/clam homogenate with viable cells of Salmonella. This assay allows for the cost effective and reliable detection of pathogenic Salmonella enterica from seafood. The mPCR developed in the present study proved to be a potent analytical tool for the rapid identification of multidrug-resistant Salmonella serovars from seafood.

Draft Genome Sequence of Multidrug Resistant Salmonella enterica serovar Weltevreden Isolated from Seafood

Salmonella enterica subsp. enterica serovar Weltevereden is the most frequent serovar isolated from Asia. Here, we report a draft genome sequence of multidrug resistant Salmonella Weltevreden 9 isolated from seafood. Whole-genome of this isolate and annotation will help enhance the understanding of this pathogenic multidrug-resistant serovar.