Efficiency of Caesalpinia sappan and Tiliacora triandra extracts on antiviral activity against Porcine Reproductive and Respiratory Syndrome Virus in weaned pig
Abstract:
Porcine reproductive and respiratory syndrome (PRRS), caused by the porcine reproductive and respiratory syndrome virus (PRRSV), is a significant epidemic that has a substantial impact on economic losses within the global pig sector. Several studies have investigated the use of plant extracts to prevent and control PRRS outbreaks. This study aimed to determined the effect of Caesalpinia sappan (CS) and Tiliacora triandra (TT) extracts for antiviral activity against PRRSV in vitro as well as investigate the potential the effect of CS and TT powders for antiviral activity against PRRSV in vivo. The CS and TT extracts were determined the phytochemical properties, antioxidant activity and in vitro antiviral activity. The CS and TT powders were mixed in various ratio (CT) to assess their antiviral activity against PRRSV in weaned pigs. The result showed that the CS extract had high total phenolic content (251.89 ± 5.41 mM gallic acid equivalent (GAE)/g extract) and antioxidant activity in 2,2-diphenyl-1-picrylhydrazyl radical scavenging capacity assay (DPPH) and 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical scavenging assay (ABTS) as half-maximal inhibitory concentration (IC50) was 3.41 ± 0.37 mg/ml and 2.66 ± 0.10 mg/ml, respectively, as well as antioxidant activity in ferric reducing antioxidant power (FRAP) assay was 205.84 ± 6.37 mM Fe (II) equivalent (Fe2+)/g extract. The antiviral activity found that CS extract significantly inhibit PRRSV infection compared with the control group (virus titer of 3.63 vs 9.25 median tissue culture infective dose (TCID50)/ml (log10)). Moreover, CS extract was significantly inhibited PRRSV replication compared with the control group (virus titer of 2.5 vs 9.12 TCID50/ml (log10)) while, TT extract significantly inhibited PRRSV infection compared with the control group (virus titer 6.33 vs 9.25 TCID50/ml (log10)). According to the results of the antiviral activity against PRRSV in vitro, the mixture of CS and TT powders for pig feed additive was found that CS and TT in 4:1 ratio had a cytotoxicity value of 62.70 µg/ml (CC50). In addition, antiviral activity in MARC-145 cells found that CS and TT as 4:1 significantly inhibited PRRSV infection and inhibited PRRSV replication (virus titer 4.5 TCID50/ml (log10)) and (virus titer 3.5 TCID50/ml (log10)), respectively. According to the efficiency of CS and TT extracts on antiviral activity against PRRSV in vitro, there was investigated the efficiency on antiviral activity against PRRSV in weaned pigs. A total of 24 weaned piglets (28 days old) were randomly allocated to four treatments using a completely randomized approach. The four dietary treatments employed were a basal diet (CON) and supplementation with CT in the basal diet at concentrations of 0.5g/kg (CT0.5), 1.0g/kg (CT1.0), and 5.0g/kg (CT5.0), respectively. Each piglet was intranasally administered 2ml of the US PRRSV strain at 1 x 104 a median tissue culture infective dose (TCID50)/ml. Pigs were housed in a biosafety level 2 facility during the experimental period for 28 days. Feed intake and clinical signs were recorded daily as well as body weight was collected weekly. Rectal temperature was measured on day 0, 7, 14, 21, and 28 post-infections. Blood was collected on day 0, 7, and 14 post-infections to determine the hematology, and serum was collected to measure viral load and antibody titer. At the end of experimental period all pigs were euthanasia to measure lung lesions. The lung tissue was collected for histopathology. The result showed that the supplementation of CT powder was not affected on productive performance. In the CT5.0 group, pigs had significantly decreased virus loads in their serum compared to the CON group (p < 0.05). All CT groups had greater PRRSV antibody titer than CON groups. In the CT5.0 group, D14 and D28 lymphocyte levels were higher than in the CON group (p < 0.05). Lastly, CT powder possess the potential to be used as feed additives for pig to inhibit the PRRSV virus infection.