Wanna Sirimanapong

Acute hepatopancreatic necrosis disease (AHPND) is caused by a plasmid bearing strain of Vibrio parahaemolyticus ( Vp _AHPND ), which produces PirA and PirB toxins that specifically target and damage hepatopancreatic and epithelial cells of the shrimp gastrointestinal tract. The impact of AHPND, together with concerns regarding antibiotic resistance, has necessitated investigations into alternative forms of disease prevention. This study evaluated the protective efficacy of Ccombody, a recombinant variable lymphocyte receptor B (VLRB)‐based antibody targeting the PirA toxin, on immune‐related gene expression and survival in Pacific white shrimp ( Penaeus vannamei ) challenged with Vp _AHPND . Shrimp were allocated into six experimental groups, each in triplicate. Two groups served as controls fed a basal commercial diet: an unchallenged negative control and a Vp _AHPND ‐challenged positive control. An additional reference group was fed a commercial diet supplemented with IgY at 500 mg/100 g feed. The remaining three treatment groups were fed diets supplemented with the Ccombody at 1, 10 or 100 mg/100 g feed for 7 days. At 7 days post‐feeding (7 d.p.f.), prophenoloxidase‐2 (proPO‐2), anti‐lipopolysaccharide factors‐1 (ALF‐1) and penaeidin‐4 (PEN4) expression levels showed no significant differences among treatments. At 24 h post‐infection (24 h.p.i.), proPO‐2 expression of Ccombody groups differed significantly from both the positive and negative control groups ( p < 0.05), while no significant differences were observed among Ccombody‐treated groups. ALF‐1 expression remained unchanged across treatments. In contrast, the Ccombody 1 and 10 mg/100 g feed groups showed significantly enhanced PEN4 expression compared to the positive control group ( p < 0.05). Notably, PEN4 expression significantly increased in Ccombody 1 mg/100 g feed group at 24 h.p.i. relative to 7 d.p.f. ( p < 0.05), whereas a decline was observed in the positive control and Ig‐Guard A groups. Principal component analysis (PCA) also showed the same scattering trend towards gene expression analysis at both 7 d.p.f. and 24 h.p.i. Dietary supplementation with Ccombody 1, 10 and 100 mg/100 g feed effectively reduced the mortality rate following challenge with V. parahaemolyticus causing AHPND. All supplemented groups showed highly significant reduction in mortality compared to the positive control group ( p < 0.001). Among them, the 10 and 100 mg/100 g feed groups exhibited the lowest mortality rates (3.70% ± 1.28% and 3.70% ± 3.39%, respectively). When considered alongside the immune‐related gene expression, these findings suggest that Ccombody has strong potential as an alternative immunoprophylaxis strategy for the prevention of Vp _AHPND .

Aquaculture faces increasing challenges from bacterial diseases and the widespread use of antibiotics, which contribute to antimicrobial resistance and environmental concerns. Oregano oil–lauric acid cationic nanostructured lipid carriers (OE-L⁺NLCs) were developed in this study and their antibacterial activity and safety were evaluated in Nile tilapia (Oreochromis niloticus). The nanoparticles were prepared using a hot homogenization–ultrasonication method and characterized based on their particle size, surface charge, morphology, and release profile. Antibacterial activity was assessed against six isolates of Streptococcus agalactiae using minimum inhibitory and bactericidal concentration assays, while their stability was evaluated under different storage conditions and simulated gastrointestinal environments. In vivo safety was determined through median lethal concentration analysis, survival assessment, and histopathology. The developed OE-L⁺NLCs showed a mean particle size of 175.90 ± 4.94 nm, positive zeta potential of +44.02 ± 0.54 mV, and low polydispersity index (0.15 ± 0.00). The formulation exhibited sustained carvacrol release (70.46 ± 0.96% over 24 h) and strong antibacterial activity against all six isolates, with MIC and MBC values of 0.25 and 0.25–0.49 mg/mL, respectively. The nanoformulation maintained antibacterial activity during 90 days of storage and under simulated gastric conditions. In vivo toxicity assessment showed that OE-L⁺NLCs exhibited a higher LC₅₀ value (11.11 mg/mL) than free oregano oil (5.89 mg/mL), together with improved survival and reduced histopathological alterations in Nile tilapia. Overall, the formulation provides an effective and stable delivery platform for natural antimicrobials, offering a promising alternative to antibiotics for sustainable disease management in aquaculture.

Group B Streptococcus (GBS) is a pathogen of global relevance in neonatal and maternal disease as well as bovine mastitis. Two closely related clonal groups, denoted 103 and 314 (CG103/314) have been detected in humans and cattle on multiple continents in recent decades but are poorly characterised compared to other host-generalist clades. We examined their potential origins, host-switching events and presence of a suite of genetic markers for antimicrobial resistance, virulence and host association using a newly assembled dataset of 248 CG103/314 genomes from humans, cattle, and food originating from five continents. We detected multiple host switches between humans and cattle, and significant regional differences in AMR gene distribution, possibly reflecting local differences in antimicrobial use across countries and hosts and indicating a capacity for regional adaptation to selective pressures. Across the evolutionary history of CG103/314 from both host species, the prevalence of the Lac.2 operon, a genetic marker associated with bovine host adaptation, was high, whereas the prevalence of the scpB-lmb gene pair, a genetic marker of human host adaptation in other GBS clonal groups, was very low. All isolates with scpB-lmb were associated with human disease rather than carriage. Our dataset displayed biases typical of research into multi-host pathogens, when sampling is often focused on a specific host species or setting. Consistent, balanced, contemporaneous and sympatric sampling efforts across host species and sources are needed for a full understanding of the distribution and emergence of CG103/314 and similar multi-host pathogens impacting food safety and public health.

This study investigated the anticancer efficacy of Varanus saltator serum. The inhibitory effects of these fractions were evaluated against a panel of cancer cell lines (A375, CaCO2, CAL27, NCI-H460, HeLa, HCT8, HT29, HepG2, KATO III, MCF-7, MDA-MB-231, Raw264.7, SKOV-3, SW620, T47D, and U937) and normal cell lines (HaCaT, MRC5, and Vero). Native peptides demonstrated higher anticancer activity compared to protein hydrolysates, inhibiting 16 cell lines and exhibiting high efficacy (≥70% inhibition) against CaCO2, CAL27, HaCaT, HT29, HepG2, MCF-7, MRC5, and U937. These native peptides were further fractionated by stepwise reverse-phase column chromatography. The hydrophilic (C18 unbound) peptide fraction exhibited greater anticancer activity than the hydrophobic (C18 bound) fraction. In addition, by LC-MS analysis, the peptide sequences were screening in silico. The predictions showed that 159 of the 432 Varanus peptides had the potential to be anticancer peptides (ACPs), of which the top twenty had a probability of more than 75%. The anticancer mechanism of peptides may be explained by the mechanism of cell entry or action. Further peptide synthesis and modification should be the next step to enhance the anticancer efficacy of these peptides with less toxicity to Vero cells. This finding sets the way for the development of new anticancer drugs originating from Varanus salvator serum peptides.

Crocodilians are susceptible to a range of virus infection including influenza A virus (IAV). However, little is known about the ecology and epidemiology of IAV in crocodile species. This study aimed to investigate IAV infection in farmed Siamese crocodiles in central Thailand. We collected plasma samples and pharyngeal swab samples from Siamese crocodiles residing in 13 crocodile farms in 9 provinces of central Thailand during 2019. Additional archival plasma samples of Siamese crocodiles collected in 2012 and 2018 were also included in the study. Plasma samples were screened for influenza A antibodies by a hemagglutination inhibition (HI) assay and positive were evaluated by a cytopathic effect/hemagglutination based-microneutralization (MN) assay. Swab samples were tested for influenza viral RNA by a real-time RT-PCR assay targeting the influenza matrix (M) gene. Among 246 tested plasma samples, the overall seroprevalence of antibodies against IAV in farmed Siamese crocodiles was 17.5% (43/246). The most common hemagglutinin (HA) subtype was H2 (46.5%, 20/43) followed by H9 (39.5%, 17/43), human H1 (14%, 6/43) and H1 (7%, 3/43). Multiple HA subtypes were also detected in 7% (3/43) of infected crocodiles with combination of H1 and H2 subtypes. All 126 tested swab samples were negative for influenza viral RNA. In addition, we demonstrated the ability of wild-type IAV subtypes (H1, H2, H9 and human H1) to infect primary Siamese crocodile fibroblast cells. To our knowledge, this is the first report of serological evidences of avian and human IAV infection in Siamese crocodiles. Our findings highlighted the role of crocodile species in the ecology of IAV particularly the potential to serve as the reservoir or mixing vessel for the viruses that significantly threaten both human and animal health.

Group B Streptococcus (GBS) is a major pathogen of humans and aquatic species. Fish have recently been recognized as the source of severe invasive foodborne GBS disease, caused by sequence type (ST) 283, in otherwise healthy adults in Southeast Asia. Thailand and Vietnam are among the major aquaculture producers in Southeast Asia, with GBS disease reported in fish as well as frogs in both countries. Still, the distribution of potentially human-pathogenic GBS in aquaculture species is poorly known. Using 35 GBS isolates from aquatic species in Thailand collected from 2007 to 2019 and 43 isolates from tilapia collected in Vietnam in 2018 and 2019, we have demonstrated that the temporal, geographical, and host-species distribution of GBS ST283 is broader than previously known, whereas the distribution of ST7 and the poikilothermic lineage of GBS are geographically restricted. The gene encoding the human GBS virulence factor C5a peptidase, scpB, was detected in aquatic ST283 from Thailand but not in ST283 from Vietnam or in ST7 from either country, mirroring current reports of GBS strains associated with human sepsis. The observed distribution of strains and virulence genes is likely to reflect a combination of spill-over, host adaptation through the gain and loss of mobile genetic elements, and current biosecurity practices. The plastic nature of the GBS genome and its importance as a human, aquatic, and potentially foodborne pathogen suggests that active surveillance of GBS presence and its evolution in aquaculture systems may be justified.

Background and Aim: For a decade, chlamydial and herpesvirus infections have caused significant morbidity and mortality in farmed crocodiles. In September 2017, a total of 160 juvenile freshwater Siamese crocodiles (Crocodylus siamensis) with conjunctivitis/pharyngitis lesions were admitted at the Veterinary Aquatic Animal Research Health Care Unit, Faculty of Veterinary Science, Mahidol University. All crocodiles did not respond well to antibiotics or supportive treatments and died. This study aimed to detect and identify the causative agents associated with conjunctivitis/pharyngitis and fatal outcomes in juvenile farmed Siamese crocodiles. Materials and Methods: A total of 138 pharyngeal and conjunctival swabs and conjunctival scrapes were collected from live crocodiles. All swab and scrape samples were DNA-extracted and amplified by polymerase chain reaction (PCR) using Chlamydiaceae- and herpesvirus-specific primers. Tissue samples (brain, lung, liver, heart, spleen, and intestine) were collected from two representative postmortem animals. All tissue samples were processed for molecular and pathological analyses. Results: PCR examinations identified chlamydial and herpesvirus DNA in 92% (126/138) and 100% (138/138), respectively, of the tested swab and scrape samples. Of those positive samples, 79% (26/33), 67% (4/6), and 98% (97/99) of the pharyngeal swabs, conjunctival swabs, and conjunctival scrapes, respectively, were positive for both chlamydial and herpesvirus DNA. Histopathological examination indicated necrosis and mononuclear cell infiltration in the liver, kidney, and intestine of the affected animals. The intracytoplasmic accumulation of Chlamydia was randomly observed in the examined tissue sample. Moreover, the presence of chlamydial and herpesvirus DNA was also detected in the tissue samples, including the heart, intestine, brain, lung, liver, and spleen, of the affected animals by PCR. Phylogenetic analyses revealed that Chlamydia spp. detected in the juvenile Siamese crocodiles was notably different from other known species in the Chlamydia genus, while the herpesvirus detected in the crocodiles was closely related to crocodyline herpesvirus 1. Conclusion: Based on histopathological and molecular examinations, this report provided the first evidence of coinfection of Chlamydia spp. and crocodyline herpesvirus 1 in juvenile Siamese crocodiles in Thailand.