Jasim Uddin

Phage therapy has enormous potential in combating bacterial resistance in food animals. However, its application via the oral route remains limited due to challenges associated with the gastrointestinal tract (GIT) environment and a lack of rigorous clinical trial evidence. Therefore, we systematically searched in Google Scholar, PubMed, Scopus, and Web of Science databases following PRISMA guidelines and finally identified 111 articles on oral phage therapy in food animals from where we summarized the key physiological and chemical factors of the gut environment hindering the effectiveness of oral phage therapy (OPT), examined the methods used to evaluate phage stability in the GI environment, and highlighted potential strategies to mitigate these challenges. In addition, we performed quantitative analysis to visualize in vitro pH and thermal stability patterns of phages targeting bacteria isolated from food animals and variability in buffer and incubation period across stability studies. The GIT consists of several anatomically and functionally distinct segments, where complex interactions occur among digestive enzymes, gastric acids, electrolytes, commensal microbiota, and mucosal immune components. The acidic pH of the stomach is a major barrier to successful oral phage delivery. According to our analysis of pH stability testing data from the reviewed studies, most phages targeting antimicrobial-resistant bacteria in food animals remained stable at pH 5–9 and inactivated under highly acidic (pH ≤ 2) or highly alkaline (pH ≥ 11) conditions. In addition, phages are susceptible to high temperatures (above 60 °C), digestive enzymes (e.g., pepsin, trypsin, lipases), bile salts, and host immune responses. Several in vitro laboratory techniques are available to assess phage stability under simulated GI conditions, but variations occur in the assessment protocols. Microencapsulation using alginate and chitosan has been used to protect phages from the adverse GI environment. Additionally, enteric-coated capsules, antacids, co-encapsulation with acid-neutralizing agents, consumption of alkaline water, and daily phage administration are suggested to improve phage survival and efficacy. For the successful clinical implementation of OPT in food animals, future research should focus on elucidating the molecular and physicochemical determinants of phage stability, understanding the humoral immune response to OPT, standardizing laboratory protocol for assessing phage viability, improving the scalability of encapsulation methods, and exploring other potential delivery techniques.

Background
Feline coronavirus (FCoV) causes inapparent to progressive fatal feline infectious peritonitis (FIP) in domestic and wild cats, which affects multiple-organ systems.

Methods
We investigated three clinically sick cats using different laboratory and molecular tests to diagnose and confirm FCoV and propagate the virus in Vero cell culture.

Results
All the cats exhibited effusive FIP with multiple clinical signs. The haematology profiles revealed lymphopenia in all cases and leukopenia, neutropenia and regenerative left shift in one case. Serum biochemistry showed elevated creatine kinase, aspartate aminotransferase, hyperbilirubinaemia and hypoalbuminaemia in all the cases. Urinalysis revealed bilirubinuria in two cases and marked proteinuria in another. All effused samples showed a positive Rivalta test, and the cytology showed a mixed pyogranulomatous inflammatory exudate. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) confirmed that all the cats were infected with FCoV. The specific gene sequencing of three isolates clustered in the same clade of the phylogenetic tree, suggesting a closely related genotype associated with FIP in cats. Feline coronavirus induced cytopathic effects (CPEs) in Vero cells, first appearing on day 5 post-infection (pi) in the primary passage. In the second passage, more distinct CPEs, including cell rounding, shrinkage, detachment and death, were evident from day 2 pi. Reverse transcription quantitative polymerase chain reaction confirmed active viral replication, with significantly decreasing Ct values across passages.

Conclusions and clinical importance
The adaptation and propagation of FCoV in a non-feline cell line provide promising opportunities for future studies, including generating sufficient viral RNA for sequencing, evaluating antiviral resistance, and establishing a practical in vitro system for drug screening and vaccine development.

Bovine viral diarrhea virus (BVDV) is globally endemic, with the ability to establish persistent infection (PI) being central to its complex epidemiology. Currently the genetic variability of BVDV in Bangladesh remains poorly understood. This study involved a survey in commercial dairy herds in the south-eastern part of Bangladesh in 2024/2025. A total of 373 blood samples were collected from cattle in 24 dairy herds. Serum and buffy coat samples were analyzed using antibody-ELISA and RT-qPCR targeting the 5′-UTR region, followed by sequencing. The MDBK cell line was used for virus isolation and biotyping. Herd and animal-level seroprevalences were 83.3% and 15.3%, respectively, while the corresponding viremic rates were 79.2% and 11.0%. Analysis of 41 sequences identified nine distinct BVDV-1 subgenotypes (1a, 1b, 1c, 1d, 1e, 1 k, 1p, 1o, and 1v), with BVDV-1b (41.5%) and BVDV-2a (14.6%) predominating. Additionally, five HoBiPeV-a pestiviruses were detected. Among antigen-positive cattle, 38 (92.68%) were identified as transiently infected and 3 (7.3%) were confirmed as PI. Six (14.6%) and 27 (65.9%) were identified as cytopathic and non-cytopathic biotypes, respectively. Risk factors for BVDV seropositivity included: female sex (OR: 3.0), clinical disease in the past three months (OR: 2.4), crowding (OR: 2.9), and lack of dedicated clothing for farm workers (OR: 5.7). Active infection was associated with calves (OR: 6.2), heifers (OR: 2.3), stunted growth (OR: 3.0), technician-performed artificial insemination (OR: 10.4), and frequent neighboring farm visits (OR: 3.1). This study has provided data crucial for formulating prevention and control strategies against BVDV to safeguard the Bangladeshi dairy industry.

Bacteriophages (phages) are viruses that infect and may kill bacteria. Phage therapy has gained global attention as a possible means to circumvent problems of bacterial antimicrobial resistance (AMR) in food animal production systems. In preparing this overview on the use of phage therapy in terrestrial food animals, 127 published research articles were analysed to obtain a contemporary background on phage therapy, the efficacy of phage administration, research gaps, and future research directions. Most of the published in vivo trials in chickens described administering phages as biocontrol agents, whereas in vivo trials in pigs administered phages as therapeutics. Only a few trials were conducted in cattle and sheep, targeting foodborne, udder and skin infections. The most common target bacteria in poultry trials were Salmonella Enteritidis, followed by Escherichia coli, Salmonella Typhimurium, Salmonella Pullorum, and Campylobacter jejuni. In contrast, antimicrobial resistant strains of S. Typhimurium and E. coli were the target bacteria in the pig trials. Most studies administered phage cocktails rather than single phage preparation, with bacterial challenge doses varying from 10³ to 10¹⁰ colony forming units (CFU), and phage doses ranging from 10⁵ to 10¹¹ plaque forming units (PFU). In all the reviewed studies phage treatment consistently reduced bacterial load by 0.4–5.0 log₁₀ CFU in feces, meat, and both external and internal organs. Moreover, as a therapeutic, phages were reported to cure diarrhea, improve nutrient digestibility, and enhance weight gain. Phage therapy also reduced specific serum IgG levels against the target bacteria and lowered neutrophil counts and TNF-α concentrations. Together these studies suggest that phage therapy may be an effective treatment approach in controlling certain key infections and hence alleviating bacterial resistance in food animals. Nevertheless, global collaboration and inclusive research on cost-effective production, efficient delivery methods, phage resistance, and host immune responses are essential for overcoming hurdles and facilitating the widespread application of phage therapy in food animals.

Classical swine fever (CSF) is an important viral disease of pigs caused by classical swine fever virus (CSFV), with major impacts on animal health and the livestock industry. This study aimed to estimate the seroprevalence of CSFV antibodies in pigs in Bali, assess potential risk factors associated with seropositivity, and describe pathological changes in clinically suspected cases confirmed by rRT-PCR. From September to December 2023, 470 blood samples from pigs with no available vaccination records were collected across Bali and tested using C-ELISA. In addition, 15 pigs showing CSF signs were necropsied for pathological and rRT-PCR evaluation. Six were confirmed CSFV-positive. The overall seroprevalence was 40.8% (192/470, 95% CI: 36.4–45.4). The highest prevalence occurred in Klungkung regency (65.4%, 17/26). Pigs from urban areas were 1.76 times more likely to be seropositive (OR: 1.76, 95% CI: 1.18–2.64) than those from rural areas. By age, pigs under two years were 1.21 times more likely to be seropositive (OR: 1.21, 95% CI: 0.65–2.23), while crossbred pigs were 1.27 times more likely (OR: 1.27, 95% CI: 0.85–1.88) compared to purebreds; however, these differences were not statistically significant. Only location (urban vs. rural) showed a significant association. Pathological changes were observed in the skin, brain, trachea, lungs, kidney, spleen, and intestines. This study demonstrates a relatively high seroprevalence of CSFV in Bali. The limited vaccination records suggests minimal vaccine coverage, indicating that the high seroprevalence most likely reflects natural infection.

Bovine viral diarrhea virus (BVDV) remains a signiicant and highly contagious pathogen that markedly impacts production and reproductive performances of diierent animals worldwide. .is review represents the global epidemiology of BVDV, emphasizing its genetic diversity, prevalence, host range, associated risk factors, diagnostic advancements, and control strategies. A systematic electronic search was performed to retrieve relevant published articles. A total of 248 studies published over the past 26 years (from January 2000 to March 2025) across 69 countries were included. Data showed that BVDV-1 has been detected across all the continents and comprises 25 subgenotypes (1a-1x and Chinese ZM-95), of which the predominant subgenotypes are 1a, 1b, and 1c. Multiple subgenotypes, such as BVDV-1f, 1g, 1h, 1k, 1l, 1r, 1s, 1t, 1u, and 1x, were distinct and circulating in European countries. Additionally, ,ve subgenotypes (2a–2e) of BVDV-2 have been identiied, with BVDV-2a being the most frequently reported in diierent geographical locations. Notably, the emergence of HoBi-like pestivirus subgenotypes (BVDV-3a–3d) has been detected in Russia, Italy, ,ailand, India, and Bangladesh. Overall, the high prevalence of BVDV has been reported in various European (2.9%–87.1%) and Asian countries (0.2%–89.49%). Although cattle are the primary host, BVDV infections have been documented across a wide range of domestic and wild species, including buualo, sheep, goats, deer, bison, yak, camelids (camels, alpacas, and llamas), pigs, and wild boar. While Ag/Ab-ELISA remains a widely used diagnostic method, advanced techniques, such as RT-qPCR, CRISPR-Cas12a, RT-LAMP, and genome sequencing, are utilized for connrmatory identiication and genotyping of BVDV. Introduction of persistently infected (PI) animals into herds, grazing on common pasture, animal movements, mixed farming practices, and unhygienic breeding practices were frequently documented as potential risk factors. Key measures for controlling and eradicating BVDV include culling of PI animals, prophylactic vaccination, and avoiding mixed farming practices.

The bovine viral diarrhea virus (BVDV) infects a wide range of domestic and wild mammals. This review hypothesized that there might be cross-species transmission of BVDV. Therefore, the aim was to explore the BVDV-5′ UTR and N-pro sequence-based evidence to understand host plasticity among different animals. A total of 146 unique BVDV sequences retrieved from GenBank, originating from 12 distinct mammalian species that are submitted from 55 countries, were analyzed. The phylogenetic analysis revealed that all three BVDV species exhibited genetic relatedness infecting diverse animal species. BVDV-1 sequences obtained from cattle, buffalo, and pigs and BVDV-2 and HoBi-like pestivirus sequences from cattle, goats, and sheep showed a genetic resemblance. Surprisingly, cattle and buffalo in China, cattle and yak in Mongolia, cattle and wild boar in Serbia, cattle and deer in Mexico, cattle and alpacas in Canada, goats and pigs in the USA, and sheep and buffalo in Argentina were infected with BVDV-1 within the same county and strongly positioned in the same cluster, indicating potential spillover with host tropism. Moreover, BVDV sequences isolated from various neighboring countries clustered closely, suggesting potential cross-border transmission events. Based on genomic evidence, the BVDV transmission cycle could be depicted, where cattle act as a primary source of infection, while other domestic and wild animals maintain the infection ecology within their habitat due to virus tropism.

In sheep, the innate immune response of mammary epithelial cells (MECs) plays a central role in combating mastitis, yet our understanding of their resistance mechanisms remains limited. This study aimed to elucidate the gene expression profiles of ovine MECs following in vitro stimulation with Staphylococcus aureus (S. aureus) using RNA-Seq technology. Bioinformatics analysis identified a total of 175 differentially expressed genes (DEGs), including 172 up-regulated and 3 down-regulated genes in the stimulated group compared to the non-stimulated control group. Gene ontology annotation and functional pathway analysis indicated that these DEGs are primarily involved in ribosomal functions, which are essential for protein synthesis and first target of pathogens, as well as in immune response dysregulations, infection, phagocytosis, and bacterial invasion of epithelial cells. Validation via quantitative real-time PCR (qRT-PCR) confirmed the RNA-Seq results. Our results revealed that DEGs converged on innate immune pathways (TLR, NOD-like receptor, NF-κB, MAPK), cytoskeletal remodeling and translational control, indicating inflammatory activation and cell injury in oMECs and highlighting candidate targets for mastitis resistance selection against S. aureus. These findings significantly contribute to the understanding of how ovine MECs respond to S. aureus stimulation, providing a foundation for further research, particularly regarding the immune defense mechanisms, strategies and implications in dairy industry.

Over the decades, cattle have not been considered primary hosts for influenza A viruses (IAV), and their role in influenza epidemiology has been largely unrecognized. While bovines are known reservoirs for influenza D virus, the recent emergence of highly pathogenic avian influenza (HPAI) H5N1 clade 2.3.4.4b in U.S. dairy cattle marks an alarming shift in influenza ecology. Since March 2024, this virus has affected thousands of dairy cows, causing clinical signs such as fever, reduced feed intake, drastic declines in milk production, and abnormal milk appearance. Evidence suggests that the virus may be replicated within mammary tissue, raising urgent concerns about milk safety, foodborne transmission, and occupational exposure. This review highlights the unprecedented expansion of viruses into bovine populations, exploring the potential for host adaptation, and interconnected roles of pets, peridomestic animals, and human exposure within shared environments. The potential impacts on dairy production, food safety, and zoonotic spillover highlight the urgent need for integrated One Health surveillance to stay ahead of this evolving threat.

Lumpy skin disease virus (LSDV), a transboundary pathogen threatening cattle health in South and Southeast Asia, presents growing challenges for disease control. This study combined serological, molecular, and genomic approaches to investigate LSDV in Barura Upazila, Bangladesh. Serological screening of 424 cattle using a commercial ELISA revealed a high seroprevalence of 55.5% (95% CI: 50.7–60.3), indicating widespread exposure. Although differences were observed by age and breed, no significant associations were found with seropositivity, suggesting broad regional circulation. Real-time PCR confirmed LSDV DNA in all 20 clinically infected animals, with consistent P32 gene amplification. Two samples with low Cq values underwent whole-genome sequencing. The complete genomes of LSDV-L2/2024 and LSDV-L3/2024 showed >99.6% identity with the reference strain LSDV-29, yet carried unique genomic features, including truncated or variant ORFs and immune-related gene differences. Phylogenetic analysis of the DNA polymerase gene revealed distinct clustering: L2/2024 aligned with South Asian isolates, while L3/2024 grouped with strains from Africa, the Middle East, and Europe. These results highlight co-circulation of genetically diverse strains and possible cross-regional introductions. Overall, our findings underscore the evolutionary plasticity of LSDV and the critical need for ongoing genomic surveillance to guide targeted vaccine development and disease control strategies.