About

Panchan Sitthicharoenchai is an Assistant Professor at the College of Veterinary Medicine at NC State University. His contact email is psitthi@ncsu.edu and his phone number is 919-513-6275. The page indicates his role within the Anatomic Pathology Hospital, but does not provide specific details about his research focus, background, or key contributions.

Research topics

• Virology
• Medicine
• Veterinary medicine
• Genetics
• Biology
• Microbiology
• Immunology
• Environmental health
• Internal medicine
• Zoology

Selected publications

• Lectin-Based Antiviral Strategies for Porcine Reproductive and Respiratory Syndrome Virus 2 Infection: Griffithsin Suppresses Viral Replication In Vitro and Reduces Early Viremia In Vivo

  Microorganisms · 2026-05-12

  articleOpen access

  Porcine reproductive and respiratory syndrome virus (PRRSV) remains a major challenge to swine production worldwide. Current vaccines have limited efficacy against genetically diverse PRRSV strains. Therefore, strategies with alternative modes of action—such as antiviral approaches that target conserved virus–host interactions, including viral attachment and entry, rather than relying solely on adaptive immune responses—are needed. We first evaluated the in vitro effect of griffithsin (GRFT), a high-mannose-binding lectin, in the monkey kidney cell line MARC-145. Cells were pre-treated with GRFT (50–200 µg/mL) prior to PRRSV infection, after which cell morphology and viral RNA replication (measured by RT-qPCR) were assessed. Pre-treatment with 100–200 µg/mL GRFT, followed by PRRSV inoculation at a multiplicity of infection of 1 or 10, reduced viral replication in MARC145 cells in a dose-dependent manner, achieving almost 100% inhibition of ORF5 and ORF7 RNA compared with untreated controls (p < 0.0001). We next investigated the in vivo effects of intranasal GRFT administration (7.5 or 15 mg/day) in pigs (n = 56). Pigs treated with 15 mg/day GRFT exhibited significantly reduced (p < 0.05) viremia 2, 4 and 7 days post-challenge, compared with untreated, challenged, and controls (log10 8.1 ± 0.2 vs. 9.0 ± 0.25, 8.2 ± 0.1 vs. 9.1 ± 0.2, and 8.9 ± 0.2 vs. 9.3 ± 0.2, respectively), along with earlier resolution of fever and a trend toward increased average daily gain over 42 days (p < 0.1). These findings are the first report of GRFT efficacy in pigs and support its potential as an antiviral strategy against PRRSV, alongside existing interventions.

  PublisherOA PDFDOI

• The evolving story of Streptococcus gallolyticus: classification, pathogenesis, role in human and animal disease, and laboratory diagnostics

  Frontiers in Microbiology · 2026-02-11

  articleOpen accessSenior author

  Streptococcus gallolyticus , formerly known as S. bovis , belongs to the Streptococcus bovis / Streptococcus equinus complex (SBSEC). Besides being a part of the gut microbiome, this organism has gained interest due to its association with infective endocarditis and its strong correlation with colorectal cancer in humans. In veterinary medicine, systemic infection caused by S. gallolyticus has been reported in various animal populations, including porcine, ruminant, and avian species. Despite its clinical importance in humans and animals, two key challenges persist: the limited understanding of the pathogenesis due to its ubiquitous nature and inconsistencies in diagnostic laboratory reporting of the bacteria in SBSEC. This review summarizes the taxonomic characterization of the SBSEC, its clinical manifestations across species, current understanding of the bacterial pathogenesis, and the laboratory diagnostic assays used for its detection. We will further discuss the importance of SBSEC speciation and subspeciation, highlighting their distinct clinical implications and potential impact on human and animal health.

  PublisherOA PDFDOI

• Exophthalmos and Buphthalmos in Broiler Breeders Associated with Marek's Disease Virus

  Avian Diseases · 2025-10-24

  articleOpen accessSenior author

  Reporte de caso- Exoftalmos y buftalmos en reproductoras de pollos de engorde asociadas al virus de la enfermedad de Marek. Este estudio investigó la ceguera acompañada de exoftalmos unilateral o bilateral en cuatro parvadas de reproductoras de pollos de engorde. El examen histopatológico reveló queratitis, edema corneal, cataratas, uveítis y pectenitis. Además, se observó degeneración retiniana y ocasionalmente cuerpos de inclusión intranucleares, compatibles con herpesvirus, en la capa ganglionar. El análisis inmunohistoquímico de las secciones oculares reveló una mezcla de células T (CD3+) y células B (Pax5). Se detectó ADN del virus de la enfermedad de Marek tipo 1 (MDV-1) en todas las muestras de nervio óptico, líquido vítreo, retina, córnea, iris y cristalino, en niveles similares o superiores a los encontrados en el bazo. Si bien la carga de ADN del virus de la enfermedad de Marek-1 fue compatible con los niveles de latencia en todas las muestras, fue mayor en las estructuras oculares con lesiones macroscópicas y microscópicas evidentes. El nivel de ADN detectado fue compatible con la latencia del virus de la enfermedad de Marek en bazos y ojos; sin embargo, no se detectó el gene pp38 del virus de Marek oncogénico. Se han reportado lesiones similares en pollos vacunados contra el herpesvirus del pavo al ser expuestos a un virus e Marek muy virulento plus (vv+). Este es el primer informe que sugiere una posible asociación con lesiones oculares inducidas por el virus de la enfermedad de Marek en pollos vacunados con CVI988 que recibieron protección adecuada contra el desarrollo de tumores inducidos por el virus de Marek.

  PublisherOA PDFDOI

• Effect of dietary vitamin D on PRRSV disease severity and immune response in nursery pigs

  AASV Annual Meeting · 2025-02-15

  article
  PublisherDOI

• T cell-mediated clearance of porcine reproductive and respiratory syndrome virus (PRRSV) from the lung characterized by machine learning analysis in vaccinated and unvaccinated pigs

  Research Square · 2025-04-30

  preprintOpen access
  PublisherDOI

• Novel <i>Cardiac Troponin-I</i> Missense Variant (c.593C&gt;T) Is Associated With Familial Hypertrophic Cardiomyopathy in Golden Retrievers

  Circulation Genomic and Precision Medicine · 2025-08-22

  articleOpen access

  BACKGROUND: Hypertrophic cardiomyopathy (HCM) is a naturally occurring cardiac disorder afflicting humans, cats, rhesus macaques, pigs, and rarely dogs. The disease is characterized by maladaptive left ventricular wall thickening. Over 1500 sarcomere-coding mutations explain HCM in humans, whereas only 3 have been reported in cat breeds. To date, no mutations have been described in dogs. HCM in a nuclear family of Golden Retrievers was identified following the sudden cardiac death of 3 related puppies &lt;2 years of age from 2 dam-offspring repeat matings. METHODS: Whole-genome sequencing on the 3 affected puppies, along with nuclear family members (ie, sire, dam, 4 unaffected littermates, 4 unaffected half-siblings), and 1 distantly related, geriatric, cardiovascularly normal Golden Retriever was performed (n=14). Candidate variant genotyping was performed in an unphenotyped cohort of dogs (n=2771) and an expanded population of phenotyped, unrelated Golden Retrievers (n=45). Left ventricular tissue immunofluorescence staining was subsequently performed to investigate incorporation and expression of mutant protein within the cardiac sarcomere of HCM-affected cases. RESULTS: Gross and histopathologic evaluations of the HCM-affected puppies revealed hallmark features of the disease, including cardiomyocyte hypertrophy, interstitial fibrosis, and left-sided congestive heart failure. Segregation analysis of called variants, performed under assumptions of an autosomal-recessive mode of inheritance, identified a single segregating c.593C&gt;T missense variant in TNNI3 ( Cardiac Troponin-I ). This variant was not observed in the unphenotyped (n=2771) nor in the phenotyped, unrelated cohort of dogs (n=45). Immunofluorescence staining of left ventricular tissues did not reveal obvious aberrant protein localization and expression at the sarcomeric level, suggesting the molecular pathogenesis of the TNNI3 variant is not related to abnormal protein incorporation within the sarcomere. CONCLUSIONS: This variant represents the first-ever reported HCM-associated variant in any canine species, and its identification holds promise for establishing translational models, genetic screening, and early disease prevention within the breed.

  PublisherOA PDFDOI

• T cell-mediated clearance of porcine reproductive and respiratory syndrome virus (PRRSV) from the lung characterized by machine learning analysis in vaccinated and unvaccinated pigs

  Vaccine · 2025-09-27

  articleOpen access

  Porcine reproductive and respiratory syndrome (PRRS) modified live virus (MLV) vaccines likely confer partial protection against heterologous wild type challenge through broadly reactive T cells. Therefore, the efficacy of Ingelvac PRRS® MLV alone and reconstituted with Ingelvac CircoFLEX® was assessed by comparing the ability to induce a robust cell-mediated immune response and confer protection against challenge. This study utilized both classic immune assays and machine learning software for measuring the cell-mediated immune response to PRRSV vaccination and challenge. Both vaccine groups had significantly reduced viremia, lung viral load, gross and microscopic lung lesions and improved average daily gain compared to the mock vaccinated group. The T cell analysis in the lung revealed a robust response to PRRSV infection leading to marked clearance of virus from the lung in the absence of neutralizing antibodies.

  PublisherDOI

• Influence of added 1,25(OH)2D3-glycoside on nursery pig growth performance, bone measurements, and cytokine concentrations

  Translational Animal Science · 2024-01-01 · 1 citations

  articleOpen access

  Abstract A total of 2,268 crossbred pigs (L337 × 1050, PIC; initially 5.5 ± 0.18 kg) were used in a 42-d growth study to evaluate the effects of 1,25(OH)2D3-glycoside provided from a plant extract on growth performance, bone characteristics, and serum criteria of nursery pigs. Pigs were weaned at approximately 21 d of age and randomly assigned to 1 of the 3 dietary treatments in a randomized complete block design. A total of 84 pens were used with 27 pigs per pen and 28 replications per treatment with pens blocked by BW and date of entry into the facility. Treatment diets were corn–soybean meal-based and consisted of a control diet (1,653 IU/kg of vitamin D3), or the control diet with 1.2 or 2.0 μg of 1,25(OH)2D3-glycoside/kg. Blood samples were collected from 25 gilts/treatment on days 21 and 42 to assess 25(OH)D3, cytokine concentrations, and antibody titers. At the end of the study, 10 pigs per treatment were euthanized and the right fibula, metacarpal, second and 10th ribs were collected to determine bone density, breaking strength, and percentage bone ash. Overall, there was a tendency (linear, P = 0.067) for a reduction in G:F as added 1,25(OH)2D3-glycoside increased, but no significant effects on final BW, ADG, ADFI, or mortality were observed. There were no treatment × bone interactions for bone breaking strength and bone ash. Percentage bone ash increased (linear, P = 0.030) across all bones as 1,25(OH)2D3-glycoside increased. Treatment did not affect bone ash weight and breaking strength. Metacarpals and 10th ribs had the greatest bone ash weight followed by the fibula with the second ribs having the lowest (P &amp;lt; 0.05). Metacarpals had greater breaking strength compared to all other bones, followed by the fibula and 10th rib, with the second rib having the lowest (P &amp;lt; 0.001). There was a bone × treatment interaction for bone density, where increasing 1,25(OH)2D3-glycoside increased bone density for the second rib (P = 0.012), but there was no treatment difference for other bones. There was no difference between treatments for antibody titers, 25(OH)D3 status, or circulating cytokine concentrations except for IL-8 concentrations which decreased (linear, P = 0.037) as 1,25(OH)2D3-glycoside increased. In summary, adding 1.2 or 2.0 μg 1,25(OH)2D3-glycoside/kg provided from a plant extract to a diet already containing 1,653 IU/kg of vitamin D3 had no effect on growth or the evaluated serum parameters; however, increasing 1,25(OH)2D3-glycoside increased percentage bone ash.

  PublisherOA PDFDOI

• Effect of bone and analytical method on assessment of bone mineralization in response to dietary phosphorus, phytase, and vitamin D in finishing pigs

  Journal of Animal Science · 2024-01-01 · 2 citations

  articleOpen access

  A total of 882 pigs (PIC TR4 × [Fast LW × PIC L02]; initially 33.2 ± 0.31 kg) were used in a 112-d study to evaluate the effects of different bones and analytical methods on the assessment of bone mineralization response to changes in dietary P, phytase, and vitamin D in growing pigs. Pens of pigs (20 pigs per pen) were randomized to one of five dietary treatments with nine pens per treatment. Dietary treatments were designed to create differences in bone mineralization and included: 1) P at 80% of NRC (2012) standardized total tract digestible (STTD) P requirement, 2) NRC STTD P with no phytase, 3) NRC STTD P with phytase providing an assumed release of 0.14% STTD P from 2,000 FYT/kg, 4) high STTD P (128% of the NRC P) using monocalcium phosphate and phytase, and 5) diet 4 with additional vitamin D3 from 25(OH)D3. On day 112, one pig per pen was euthanized for bone, blood, and urine analysis. Additionally, 11 pigs identified as having poor body condition which indicated a history of low feed intake (unhealthy) were sampled. There were no differences between treatments for final body weight, average daily gain, average daily feed intake, gain to feed, or bone ash measurements (treatment × bone interaction) regardless of bone ash method. The response to treatment for bone density and bone mineral content was dependent upon the bone sampled (density interaction, P = 0.053; mineral interaction, P = 0.078). For 10th rib bone density, pigs fed high levels of P had increased (P < 0.05) bone density compared with pigs fed NRC levels with phytase, with pigs fed deficient P, NRC levels of P with no phytase, and high STTD P with extra 25(OH)D3 intermediate, with no differences for metacarpals, fibulas, or 2nd ribs. Pigs fed extra vitamin D from 25(OH)D3 had increased (P < 0.05) 10th rib bone mineral content compared with pigs fed deficient P and NRC levels of P with phytase, with pigs fed industry P and vitamin D, and NRC P with monocalcium intermediate. Healthy pigs had greater (P < 0.05) serum Ca, P, vitamin D concentrations, and defatted bone ash than those unhealthy, with no difference between the two health statuses for non-defatted bone ash. In summary, differences between bone ash procedures were more apparent than differences between diets. Differences in bone density and mineral content in response to dietary P and vitamin D were most apparent with 10th ribs.

  PublisherOA PDFDOI

• High mortality associated with avian reoviral hepatitis in young quail ( <i>Colinus virginianus</i> )

  Veterinary Pathology · 2024-12-12 · 2 citations

  article1st authorCorresponding

  ) (35%-85%) was reported from a grower flock in Iowa during July and August of 2022. Two diagnostic submissions of dead, 3-day-old quail chicks were received. Postmortem examination revealed multifocal, pinpoint, pale tan foci in the liver of all birds. Histologic examination revealed moderate to severe, acute, multifocal, random necrotizing hepatitis with multinucleated cells and dystrophic mineralization. Metagenomic sequencing of liver detected orthoreovirus. A high level of avian reovirus (ARV) RNA was identified by real-time reverse transcriptase-PCR. ARV was successfully isolated from liver and lung on the Leghorn male hepatoma cell line. In addition, electron microscopy revealed orthoreovirus viral particles and virus factories in the formalin-fixed livers and viral-infected cell culture. This case highlights ARV as a potential cause of hepatitis in quail chicks and should be considered in the differential diagnosis.

  PublisherDOI

Frequent coauthors

• Christopher Siepker

  Iowa State University

  13 shared

• Mike D Tokach

  13 shared

• Jason C Woodworth

  Kansas State University

  13 shared

• Joel M DeRouchey

  13 shared

• Sarhad Alnajjar

  Iowa State University

  13 shared

• Robert D Goodband

  12 shared

• Eric Burrough

  Iowa State University

  11 shared

• Hadley Williams

  Kansas State University

  10 shared

Education

• Ph.D., Animal Science

  University of California, Davis

  2000

• M.S., Animal Science

  University of California, Davis

  1996

• B.S., Animal Science

  University of California, Davis

  1994

Awards & honors

• Diplomate of American College of Veterinary Pathologists (An…