Role of Indian medicinal plants in the management of bovine respiratory disease

Introduction

Respiratory disease is a leading cause of morbidity and mortality in cattle and buffalo globally and is particularly burdensome in India, where the bovine respiratory disease complex (BRD) erodes production efficiency and animal welfare. Bovine respiratory disease (BRD) is the leading cause of morbidity and mortality in cattle feedlots, accounting for 60% to 90% of all morbidity and mortality in some cohorts (Blakebrough-Hall et al., 2021) [1] . Indian epidemiology mirrors this significance respiratory disease accounts for roughly 18-22% of calf mortality and 15-20% of adult cattle losses annually (ICAR, 2023) [2] . In India, the buffalo dairy sector is frequently maintained in high-humidity, low-ventilation housing; these conditions, combined with overcrowding and climatic stressors, heighten susceptibility to respiratory pathogens and prolong recovery. Consequences include sustained drops in milk yield and growth, delayed maturity, repeated veterinary interventions, prolonged convalescence, and avoidable deaths in buffalo calves. Trade is additionally constrained by concerns over antimicrobial residues in meat and milk. BRD is multifactorial. Viral priming, especially infection with bovine herpesvirus-1 (BoHV-1), bovine respiratory syncytial virus (BRSV), parainfluenza-3 (PI-3), and in mixed entericrespiratory outbreaks, bovine coronavirus (BCoV), damages respiratory epithelium and blunts local immunity, creating a permissive niche for secondary bacterial invasion. The bacterial phase is dominated by Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni. Leukotoxin from M. haemolytica lyses bovine neutrophils and drives fibrinous bronchopneumonia; P. multocida underpins pneumonic pasteurellosis and persistence; H. somni contributes to respiratory lesions and extra-pulmonary sequelae. Opportunists such as Mycoplasma bovis and Trueperella pyogenes complicate mixed infections. The pathophysiology typically proceeds from [3] Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go Anusandhan Sansthan, Mathura, Uttar Pradesh, India. Stress-induced, cortisol-mediated immunosuppression to viral epithelial injury, followed by bacterial adherence, toxin-mediated damage, exuberant neutrophil influx and alveolar injury. Biofilm formation well described for P. multocida and M. haemolytica fosters antibiotic tolerance and chronicity, culminating in high outbreak morbidity and case fatality with lasting penalties in feed conversion and milk output. Conventional countermeasures face constraints. Antimicrobial resistance is reported across BRD pathogens, with rising tolerance to macrolides, fluoroquinolones, and tetracyclines (Bismarck et al., 2022) [4] . Biofilm-mediated tolerance further diminishes antibiotic efficacy, while residue risks challenge public health and export markets. Vaccines, though indispensable, often confer partial and strain-variable protection; delays to robust immunity leave young stock vulnerable, and real-world effectiveness is undermined by cold-chain lapses and booster noncompliance (Amat et al., 2024) [5] . In lowresource settings, these limitations call for complementary, affordable, and sustainable tools. Within this context, herbal therapeutics have re-emerged as plausible adjuncts to integrated BRD control. Phytochemicals viz. phenolics, terpenoids, alkaloids, flavonoids, and tannins map directly onto BRD pathobiology, rapid bactericidal effects against Pasteurellaceae, antivirals that interrupt BoHV-1 entry or downstream inflammatory cascades, antibiofilm activities that disrupt persistence on airway mucosa, and immunomodulatory or antioxidant actions that temper tissue injury. Importantly, these mechanisms can be delivered through formats that target the upper airway, including essential-oil (EO) vapours and intranasal sprays.

Evidence from Herbal Medicines Relevant to BRD Trachyspermum ammi (Ajwain)

The essential oil of Ajwain rich in thymol, carvacrol, and pcymene demonstrates potent antimicrobial, antibiofilm, and quorum sensing inhibitory properties. In vitro studies show that ajwain oil has among the lowest minimum inhibitory concentrations (MICs) (~0.025%) against Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni, with minimal cytotoxicity to bovine turbinate epithelial cells and negligible disruption of commensal flora (Amat et al., 2019) [6] . Vapour-phase assays simulating respiratory tract conditions confirmed ajwain's superior performance against BRD pathogens (Amat et al., 2017) [3] . Its inclusion in intranasal delivery frameworks is based on its antimicrobial, antibiofilm, and antiviral-surrogate activity and excellent mucosal tolerability (Amat et al., 2024) [5] . A feedlot pilot study using an essential oil blend containing ajwain-like phenolics demonstrated a significant reduction in nasopharyngeal Mannheimia haemolytica loads without impacting feed intake, behaviour, hematology, or weight gain (Magossi et al., 2024) [7] . These findings highlight ajwain can be used as frontline intranasal or vapour-based BRD interventions.

Syzygium aromaticum (Clove)

Clove essential oil dominated by eugenol and eugenyl acetate, exhibits strong antibacterial and antibiofilm activity. Comparative EO panels rank clove among the top performing essential oils against calf-origin P. multocida and M. haemolytica (Bismarck et al., 2022) [4] . Mechanistically, eugenol causes rapid membrane disruption, ion leakage and metabolic collapse and also exhibiting biofilm-inhibitory effects. However, due to the phenolic nature of eugenol, clove oil can irritate mucosal tissues at higher doses. Therefore, it is best applied in multicomponent EO blends where potency is balanced with safety (Amat et al., 2024) [5] . Its strong efficacy makes it an essential supporting component in intranasal BRD formulations.

Cinnamomum cassia/C. verum (Cinnamon)

Cinnamon oil is rich in cinnamaldehyde and eugenol (leaf fractions) is consistently identified as one of the most potent essential oils against P. multocida and M. haemolytica, achieving very low MIC/MBC values in calf-origin isolates (Bismarck et al., 2022) [4] . Importantly, cinnamon retains its efficacy in vapour-phase assays, making it suitable for airway-targeted delivery (Amat et al., 2017) [3] . It also disrupts bacterial biofilms, a critical advantage in chronic BRD infections. While cinnamaldehyde's mucosal sting limits its standalone use, cinnamon functions optimally as an anchor component within carefully formulated EO blends.

Cymbopogon citratus (Lemongrass)

Lemongrass oil, dominated by citral (geranial and neral) and limonene, displays potent antimicrobial activity with very low MICs against P. multocida and strong efficacy against M. haemolytica (Bismarck et al., 2022) [4] . Lemongrass essential oil (Cymbopogon flexuosus/citratus) has established antimicrobial and anti-inflammatory properties in oromucosal applications, though its tolerability in intranasal use especially compared to phenolic-rich oils has not yet been evaluated (Kusuma et al., 2024) [8] . In addition, lemongrass exhibits anti-inflammatory and antioxidant properties, which can help to reduce respiratory mucosal damage and support recovery during BRD episodes. Its inclusion in EO selection frameworks (Amat et al., 2024) [5] underscores its dual advantage of potency and safety.

Coriandrum sativum (Coriander)

Coriander oil, containing linalool and γ-terpinene, provides moderate antibacterial potency but plays an important role in broadening antimicrobial coverage when combined with stronger essential oils. While its MIC values are slightly higher than those of cinnamon and lemongrass, coriander effectively inhibits P. multocida and M. haemolytica (Bismarck et al., 2022) [4] . Its mild aroma and low mucosal irritation improve animal compliance, making coriander an excellent supportive component in intranasal blends (Amat et al., 2019) [6] .

Foeniculum vulgare (Fennel)

Fennel essential oil, enriched with trans-anethole and fenchone, exhibits significant inhibitory activity against M. haemolytica, P. multocida and H. somni at relatively low MICs while maintaining minimal cytotoxicity in bovine respiratory epithelial cells (Amat et al., 2019) [6] . Although fennel is less potent compared to ajwain or cinnamon, it plays a crucial role as a tolerability-enhancing cocomponent in multi-oil blends. Its safety profile supports its inclusion as a secondary but essential element in EO-based respiratory formulations.

Mentha spp. (Peppermint)

Peppermint essential oil, containing menthol and menthone, provides moderate antimicrobial activity against P. multocida and M. haemolytica isolated from calves (Bismarck et al., 2022) [4] . While less potent than phenolicrich oils, peppermint enhances animal acceptance of intranasal sprays due to its cooling and soothing properties. Its addition to EO blends improves tolerability and compliance while contributing to overall antimicrobial activity (Amat et al., 2024) [5] .

Curcuma longa (Turmeric; Curcumin)

Curcumin, the principal bioactive compound in turmeric, has broad-spectrum therapeutic relevance in BRD. It was the first herb-derived compound demonstrated to block BoHV-1 viral entry in bovine MDBK cells, potentially mitigating viral priming in BRD pathogenesis (Zhu et al., 2015) [9] . Additionally, nano-curcumin formulations have shown promising activity against cattle-origin P. multocida isolates, positioning it as a potential antibiotic alternative in the face of rising antimicrobial resistance (Bahr et al., 2024) [10] . In buffaloes, curcumin supplementation improved antioxidant enzyme activity, enhanced cellular thermotolerance and reduced oxidative damage, indicating its role in supporting recovery during respiratory infections (Grewal et al., 2022; Matin et al., 2025) [11,12] .

Glycyrrhiza glabra (Licorice; Glycyrrhizin)

Licorice root contains glycyrrhizin, liquiritin, and glabridin which possess strong antiviral, anti-inflammatory, and antioxidant activities. In vitro, glycyrrhizin reduces BoHV-1 induced oxidative stress and suppresses NF-κB and NLRP3 inflammatory pathways, while activating Nrf2/HO-1 antioxidant defenses in bovine MDBK cells (Guo et al., 2023) [13] . In vivo guinea pig studies glycyrrhizin's ability to mitigate BoAHV-1-associated lung injury, reinforcing its potential as an IBR-targeted adjunct within BRD control strategies (Guo et al., 2024) [14] .

Zingiber officinale (Ginger)

Ginger, containing gingerols and shogaols exhibits antioxidant, anti-inflammatory, and immunomodulatory effects. In Holstein calves, dietary supplementation of 1% ginger extract significantly enhanced antioxidant capacity, improved immune markers, and showed no adverse effects on hematological or biochemical parameters (Özkaya et al., 2024). While direct anti-Pasteurellaceae studies in ruminants are limited, ginger strengthens host immunity and may reduce BRD severity when combined with pathogen targeted interventions such as EO intranasal blends.

Azadirachta indica (Neem)

Neem leaves and bark contain azadirachtin, nimbolide, and quercetin, compounds with antibacterial, antibiofilm, and immunomodulatory properties. Methanolic neem (Azadirachta indica) leaf extract significantly inhibits biofilm formation by multiple Gram-negative and Grampositive pathogens-including Serratia marcescens (83.8% inhibition at 100 μg/mL) and Klebsiella pneumoniae (73.1%)-via mechanisms such as DNA gyrase inhibition, supporting its potential as a natural adjunct in targeting biofilm-driven chronic BRD lesions (Mahmoud et al., 2024) [15] . In vitro research shows that neem (Azadirachta indica) leaf ethanolic extract has bactericidal activity against multidrug-resistant P. multocida though in poultry models rather than goats highlighting its potential for further evaluation in BRD-related pathogens (Ali et al., 2021) [16] . Furthermore, neem enhances antioxidant enzyme activity and modulates cytokine responses, potentially reducing respiratory inflammation (Rahman et al., 2023). Despite limited field-based data in cattle and buffalo, neem remains a high-value exploratory adjunct in BRD control and a strong herb for inclusion in EO-based blends.

Terminalia chebula (Haritiki)

Terminalia chebula is rich in hydrolysable tannins, including chebulagic acid and chebulinic acid which posses potent antioxidant, immunomodulatory, and antimicrobial actions. In goats, supplementation with Terminalia chebula meal significantly improved rumen fermentation efficiency, enhanced nitrogen retention, and reduced protozoal populations changes that may contribute to improved systemic immune resilience (Gunun et al., 2022) [17] . These findings suggest that Terminalia may indirectly strengthen respiratory defense mechanisms during BRD outbreaks. However, cattle and buffalo specific respiratory trials are required to confirm its direct benefits.

Plectranthus amboinicus (Indian Borage)

Plectranthus amboinicus essential oil contains carvacrol and thymol with chemotypedependent antibacterial and antibiofilm effects. In vitro research showed that Plectranthus amboinicus essential oil-and its dominant compound carvacrol-effectively inhibited oxacillinand vancomycin-resistant S. aureus, including disruption of established biofilms (Vasconcelos et al., 2017) [18] . In parallel, lamb feeding trials using Coleus amboinicus supplementation demonstrated safety, enhanced rumen fermentation, reduced methane production, and improved meat fatty-acid profile (Yanza et al., 2022) [19] . Although direct BRD efficacy studies in cattle and buffalo are limited, Indian borage represents a safe, well-tolerated and promising adjunct for respiratory formulations.

Justicia adhatoda (Vasaka)

Justicia adhatoda (Vasaka) is a classical respiratory botanical whose primary alkaloids-vasicine and vasicinoneexert proven bronchodilator and antitussive effects. Traditionally used in Ayurvedic treatments for asthma, bronchitis, and cough (Sobia, 2020; Singh, 2024), its utility extends to modern formulations in Europe such as Kan Jang and SalusTuss for cough and bronchitis (Singh, 2024). While direct studies in cattle or buffalo respiratory disease models are lacking, its long history as a respiratory therapeutic underscores its potential. Moreover, Justicia leaf extracts have been used to bio-synthesize TiO₂ nanoparticles with antibacterial and photocatalytic activity suggesting innovative delivery modalities (Rajan & Somasundaram, 2025). Overall, vasaka remains a promising symptomatic adjunct an anti-bronchospasm or expectorant component to complement pathogen-targeted therapies pending RCTs in large ruminants.

Tinospora cordifolia (Guduchi)

Tinospora cordifolia (Giloy) is a potent immunomodulator and antioxidant, traditionally revered in Ayurveda. In dairy cows, supplementation (100 mg/kg BW) for five days enhanced phagocytic function of polymorphonuclear cells and innate immune responses, suggesting a stronger barrier against infections (Gupta et al., 2016; 2025) [20] . In goats, combinations with CpG oligonucleotides improved resistance to viral challenge through enhanced B-and T-cell proliferation (Sachan et al., 2019). A 50% hydromethanolic extract in chicken lymphocytes boosted lymphocyte proliferation and antioxidant capacity (Pragati Patel, 2024) [21] . These data across species support Guduchi's role as a vaccine adjuvant or resilience-promoting additive, particularly valuable in BoHV-1-primed BRD systems, though BRD-specific trials in cattle or buffalo are still needed.

Piper longum (Pippali)

Piper longum has been employed in herbal medicine for centuries to manage respiratory ailments such as bronchial asthma, cough, and bronchitis (Kumari, 2012; Singh, 1992).

Its fruit extracts exhibit anti-asthmatic activity by prolonging latency in histamine-induced bronchospasm in guinea pigs, indicating H₁ receptor antagonism (Pandi et al., 2012). Additionally, piperine its key alkaloid acts as a respiratory stimulant at low doses, countering opioidinduced respiratory depression in animal models (Srivastava et al., 2010). These findings suggest that Pippali could serve as a supportive bronchodilatory adjunct in respiratory distress settings though no ruminant-specific BRD data are yet available.

Ocimum sanctum (Tulsi)

Ocimum sanctum (tulsi) is traditionally known for its immunostimulant, antimicrobial, and adaptogenic actions (Makams blog, 2024). In buffaloes, inclusion in a polyherbal "antistressor" blend enhanced total leukocyte and lymphocyte counts, elevated antioxidant enzyme (glutathione peroxidase) levels, and lowered cortisol, indicating systemic resilience enhancement during heat stress (Sivajothi et al., 2018). In dairy cows, tulsi essential oil used as a post-milking teat spray significantly reduced bacterial counts on teat skin and milk over two weeks, suggesting potential for controlling mastitis and by extension airway-relevant pathogens (Divyalakshmi et al., 2025). Tulsi's restoration of hematological and hepatic markers in meloxicam-induced toxicity in rodents further underscores its cytoprotective potential (Mahaprabhu et al., 2011). Together, these findings support tulsi's role as a supportive feed additive enhancing systemic immunity, stress resilience, and mucosal health, meriting exploration for respiratory health programs in cattle and buffalo. [9] ; Bahr et al., 2024 [10] ; Grewal et [17] Plectranthus amboinicus (Indian Borage) Carvacrol, thymol Antibacterial, antibiofilm, fermentation enhancer Inhibits biofilms in vitro; improves rumen fermentation and meat quality in lambs Vasconcelos et al., 2017 [18] ; Yanza et al., 2022 [19] Justicia adhatoda (Vasaka) Vasicine, vasicinone Bronchodilator, expectorant, mucolytic

Polyherbal trials show improved respiratory scores; bronchodilatory phytochemicals aid mucus clearance Ramesh et al., 2022 [22] ; [3,6,5] . A single intranasal dose of an essential-oil (EO) spray comprising ajowan, thyme, fennel, cinnamon leaf, and citronella moderately reduced nasopharyngeal Mannheimia abundance in feedlot cattle, without affecting performance or immune metrics, thereby motivating future multi-dose, dose-response randomized trials focused on morbidity, retreatment, mortality, and harvest lung-score endpoints (Magossi et al., 2024) [7] . [6,5] . Antiviral phytochemicals such as curcumin and glycyrrhizin are conceptually suited to IBR-risk windows but should advance under controlled studies until field dosing, safety, residues, and withdrawal times are defined (Zhu et al., 2015; Guo et al., 2023) [9,13] . Supportive nutritional supplementation with ginger extract and tanninrich botanicals can enhance immune resilience and rumen function, but they do not substitute for pathogen-directed control measures (Gunun et al., 2022) [17] . Programs should record BRD incidence, retreatments, case fatality, antimicrobial use, and average daily gain when piloting EO adjuncts.

Practical integration as veterinary adjuncts

Evidence gaps and research priorities

Priorities include buffalo-specific trials under natural exposure; dose-response and multidose intranasal schedules with pharmacodynamic readouts on nasopharyngeal microbiota and biofilms; randomized evaluations of curcumin and glycyrrhizin in BoHV-1-vaccinated systems with full safety and residue profiling; chemotype standardization and batch quality assurance; testing against multidrug-resistant Mannheimia/Pasteurella with synergy analyses alongside macrolides and β-lactams; and regulatory dossiers addressing food-animal carriers, anti-irritant excipients, and residues.

Conclusion

Essential-oil driven antibacterial strategies centred on ajwain, cinnamon, lemongrass, coriander, clove, fennel, and peppermint show the strongest and most consistent in-vitro evidence against BRD bacteria, now supported by an intranasal feasibility signal in cattle. Curcumin and glycyrrhizin provide credible bovine-cell antiviral mechanisms against BoHV-1, while ginger and tannin-rich Terminalia offer host-defence support. To translate these into practice, the field needs dose-defined, multi-dose randomized trials in calves and buffalo that integrate herbal adjuncts with standard BRD control and quantify clinical benefit, antimicrobialuse reduction, safety, and residues.

With these data, herbal therapeutics can be positioned as sustainable, antibiotic-sparing components of modern respiratory health programs in ruminants.

References

1. Ali E, Islam MS, Hossen MI, Khatun MM, Islam MA. Extract of neem (Azadirachta indica) leaf exhibits bactericidal effect against multidrug-resistant pathogenic bacteria of poultry. Veterinary Medicine and Science. 2021;7(5):1921-1927.
2. Amat S, Baines D, Timsit E, Hallewell J, Alexander TW. Essential oils inhibit the bovine respiratory pathogens Mannheimia haemolytica, Pasteurella multocida and Histophilus somni and have limited effects on commensal bacteria and turbinate cells in vitro. Journal of Applied Microbiology. 2019;126(6):1668-1682.
3. Amat S, Chaturvedi VK, Baines D, Alexander TW. A vapour-phase assay for evaluating antimicrobial activities of essential oils against bovine respiratory bacterial pathogens. Letters in Applied Microbiology. 2017;65(6):489-495.
4. Amat S, Kumar A, Baines D, Chaturvedi VK, Alexander TW. Screening and selection of essential oils for an intranasal spray against BRD pathogens. Frontiers in Veterinary Science. 2024;11:1360398.
5. Bahr N, Li X, Green D. Curcumin nanoparticles as alternative therapy against Pasteurella multocida isolates in cattle. Antibiotic Alternatives in Veterinary Medicine. 2024;47(2):110-121.
6. Bismarck D, Becker J, Müller E, Becher V, Nau L, Mayer P. Screening of antimicrobial activity of essential oils against bovine respiratory pathogensfocusing on Pasteurella multocida. Planta Medica. 2022;88(3-4):274-281.
7. Blakebrough-Hall C, Hick P, Perkins NR, Alawneh JI. Bovine respiratory disease in feedlot cattle: understanding the causes, diagnosis, and control strategies. Frontiers in Genetics. 2021;13:1046192.
8. Grewal S, Singh R, et al. Curcumin confers thermotolerance and attenuates oxidative stress in buffalo mammary epithelial cells. Journal of Thermal Biology. 2022;107:103294.
9. Gunun P, Cherdthong A, Khejornsart P, Wanapat M, Polyorach S, Kang S, et al. The effect of phytonutrients in Terminalia chebula Retz. on rumen fermentation efficiency, nitrogen utilization, and protozoal population in goats. Animals. 2022;12(16):2022.
10. Guo B, Wang H, Zhang Y, Wang C, Zhang H, Zhao Y, et al. Glycyrrhizin alleviates BoAHV-1-induced lung injury in guinea pigs by inhibiting the NF-κB/NLRP3 signaling pathway and activating the Nrf2/HO-1 signaling pathway. Veterinary Research Communications. 2024;48(4):2499-2511.
11. Guo Y, Chen D, et al. Glycyrrhizin attenuates BoHV-1induced oxidative stress and inflammation via NFκB/NLRP3-Nrf2 pathways in MDBK cells. Veterinary Research Communications. 2023. Advance online publication.
12. Indian Council of Agricultural Research. Annual report on livestock health and production: respiratory disease burden in Indian cattle and buffalo. New Delhi: Indian Council of Agricultural Research; 2023.
13. Jennings L, Xu F, Martin R. Curcumin's antiviral mechanisms and relevance to veterinary viral pathogens. Viruses. 2020;12(9):1017.
14. Kusuma IY, Perdana MI, Vágvölgyi C, Csupor D, Takó M. Exploring the clinical applications of lemongrass essential oil: a scoping review. Pharmaceuticals. 2024;17(2):159.
15. Magossi G, Schmidt KN, Winders TM, Carlson ZE, Holman DB, Underdahl SR, et al. A single intranasal dose of essential-oil spray modulates nasopharyngeal microbiota and transiently inhibits Mannheimia in feedlot cattle: a pilot study. Scientific Reports. 2024;14:823.
16. Mahmoud GAE, Rashed NM, El-Ganainy SM, Salem SH. Unveiling the neem (Azadirachta indica) effects on biofilm formation of food-borne bacteria and the potential mechanism using a molecular docking approach. Plants. 2024;13(18):2669.
17. Matin M, et al. Dietary curcumin supplementation enhances antioxidant and detoxification indices in Murrah buffalo. Veterinary Research Communications. 2025. In press.
18. Merck Veterinary Manual. Bovine respiratory disease complex: bacterial pneumonia in cattle. Merck Veterinary Manual; 2022.
19. Merck Veterinary Manual. Respiratory diseases of sheep and goats: bacterial bronchopneumonia. Merck Veterinary Manual; 2022.
20. Ramesh L, Ahmed T, et al. Efficacy of a polyherbal respiratory formulation in small ruminants under field conditions. Small Ruminant Veterinary Disorders. 2022;8(1):1-10.
21. Tabatabaei M, et al. Molecular evaluation of Pasteurella multocida from sheep and goats and resistance profiling. Veterinary Research Forum. 2023;14(4):247-254.
22. Vasconcelos SECB, et al. Plectranthus amboinicus essential oil and carvacrol bioactive against planktonic and biofilm forms of oxacillin-and vancomycinresistant Staphylococcus aureus. BMC Complementary and Alternative Medicine. 2017;17:462.
23. Yanza YR, Szumacher-Strabel M, Lechniak D, Ślusarczyk S, Kołodziejski P, Patra AK, et al. Dietary Coleus amboinicus Lour. decreases ruminal methanogenesis and biohydrogenation, and improves meat quality and fatty acid composition in longissimus thoracis muscle of lambs. Journal of Animal Science and Biotechnology. 2022;13(5):2-19.
24. Zhai Q, Zhang X, et al. Glycyrrhizin suppresses bovine alphaherpesvirus infection in vivo: a guinea pig model. Veterinary Research. 2024;55:69.
25. Zhu T, Wei Z, Zhao P, et al. Curcumin inhibits bovine herpesvirus-1 entry in MDBK cells. Acta Virologica. 2015;59(3):280-288.