Avian coronavirus infectious bronchitis virus susceptibility to botanical oleoresins and essential oils in vitro and in vivo.
https://www.ncbi.nlm.nih.gov/pubmed/20096315
In vitro antiviral activity of fifteen plant extracts against avian infectious bronchitis virus
BMC Veterinary Research volume 15, Article number: 178 (2019)
Cite this article
Abstract
Background
Avian infectious bronchitis (IB) is a disease that can result in huge economic losses in the poultry industry. The high level of mutations of the IB virus (IBV) leads to the emergence of new serotypes and genotypes, and limits the efficacy of routine prevention. Medicinal plants, or substances derived from them, are being tested as options in the prevention of infectious diseases such as IB in many countries.
The objective of this study was to investigate extracts of 15 selected medicinal plants for anti-IBV activity.
Results
Extracts of
S. montana,
O. vulgare,
M. piperita,
M. officinalis,
T. vulgaris,
H. officinalis,
S. officinalis and
D. canadense showed anti-IBV activity prior to and during infection, while
S. montana showed activity prior to and after infection.
M. piperita,
O. vulgare and
T. vulgaris extracts had > 60 SI. In further studies no virus plaques (plaque reduction rate 100%) or cytopathogenic effect (decrease of TCID50 from 2.0 to 5.0 log10) were detected after IBV treatment with extracts of
M. piperita,
D. canadense and
T. vulgaris at concentrations of extracts ≥0.25 cytotoxic concentration (CC50) (
P < 0.05). Both PFU number and TCID50 increased after the use of
M. piperita,
D. canadense,
T. vulgaris and
M. officinalis extracts, the concentrations of which were 0.125 CC50 and 0.25 CC50 (
P < 0.05). Real-time PCR detected IBV RNA after treatment with all plant extracts using concentrations of 1:2 CC50, 1:4 CC50 and 1:8 CC50. Delta cycle threshold (Ct) values decreased significantly comparing Ct values of 1:2 CC50 and 1:8 CC50 dilutions (
P < 0.05).
Conclusions
Many extracts of plants acted against IBV prior to and during infection, but the most effective were those of
M. piperita,
T. vulgaris and
D. canadense .
Background
IB is a highly contagious respiratory and occasionally urogenital disease in chickens [
1]. IBV affects the upper respiratory tract and reduces egg production [
2]. It is a coronavirus that belongs to the
Coronaviridae family. IBV is an enveloped virus with a single-stranded positive-sense linear RNA molecule (approximately 27.6 kb in size) [
3].
IB has a wide geographical distribution and is diagnosed worldwide [
1]. IB outbreaks continuously and results in economic losses in the poultry industry. So far vaccination using inactivated or live vaccines [
4] is regarded as the main method of prevention, but it is not having the desired effect [
5,
6,
7]. The high level of mutations of IBV [
8] leads to the emergence of new serotypes and genotypes, and limits the efficacy of routine prevention.
Biological products derived from plants are used in medicine for different pharmacological reasons, including the treatment of infectious and non-infectious diseases [
9,
10]. This class of antimicrobial plants is acknowledged and well investigated, and classes of active compounds have already been identified [
11,
12]. The investigation of antiviral substances derived from plants is insufficient in comparison with the investigation of antimicrobial properties. Fortunately, several experiments have shown that plants have positive antiviral activity in vitro and in vivo [
13]. However, the same plants can have different antiviral activity against RNA or DNA viruses, either enveloped or non-enveloped, and even against different types or strains of a virus [
14,
15].
A number of scientific publications have encouraged the use of polyphenolic compounds in the treatment and prophylaxis of chronic diseases [
16]. The mixture of the geometric isomers and enantiomers of rosmarinic acid is accumulating in the families
Lamiaceae Lindl,
Asteraceae Bercht. & J.Presl [
17,
18]. Most large quantities of rosmarinic acid have been determined in the genus of plants such as
Salvia L.,
Perilla L. Melissa L. and
Echinacea Moench. Rosmarinic acid has antioxidative, anti-inflammatory, antimutagenic, antibacterial and antiviral effects against the herpes simplex virus [
19].
The
Desmodium canadense herb contains flavonoids such as apigenin, apigenin-7-O-glucoside, luteolin, rutin, 2-vicenin, vitexin, isovitexin, vitexin rhamnoside, orientin, homoorientin, quercetin, hyperoside, astragalin and kaempherol [
20]. In addition, it also contains saponins and phenolic acids (chlorogenic acid, vanillic, 4- hydroxycinnamic, ferulic and caffeic). The
Desmodium herb exhibits antioxidant, antibacterial, anti-inflammatory, hepatoprotective, diuretic and analgesic activity [
20]. C-glycosides of flavonoids are known to exhibit antioxidant, hepatoprotective, anti-inflammatory and antiviral effects [
21]. The plants in this study were chosen for their medical, antibacterial and antiviral properties. Ethanol extracts of medicinal plants belonging to the families
Lamiaceae (winter savory, perilla, blue giant hyssop, oregano, peppermint, lemon balm, thyme, hyssop, catnip and sage),
Asteraceae (chamomile and purple coneflower),
Geraniaceae (rock crane’s-bill),
Apiaceae (garden angelica), and
Fabaceae (showy tick trefoil) were prepared. The majority of plants used for the preparation of extracts in this study belong to one of the famous medicinal aromatic plant families
Lamiaceae. The medicinal plants from this family have long been used in traditional medicine worldwide.
Many investigations of plant extracts have been performed with different coronaviruses. The main targets were proteins involved in coronaviral replication, proteases and ion channel conductance [
22]. Only a few investigations have been performed to test the anti-IBV activity of plant extracts. Several studies have found that the plant preparations inhibited IBV replication in vivo and vitro.
Sambucus nigra, Houttuynia cordata, Alium sativum and
Astragalus mongholicus inhibited IBV replication [
23,
24,
25,
26]. The ethanol extract of
Sambucus nigra inhibited IBV replication and reduced virus titres prior to infection [
24], as did
Houttuynia cordata essential oil mixed with an aqueous solution of sodium chloride solution [
25]. It is suggested that the effect of extracts of,
Alium sativum, Houttuynia cordata and
Sambucus nigra can be associated with direct inactivation of envelope structures of a virus, which are necessary for adsorption to or entry into host cells, or might dissolute the IBV envelope. Compounds that have a virucidal effect work like a disinfectant and do not require replication to inactivate the virus [
15]. The mechanism of action of
Astragalus polysaccharides has not been explained.
Medicinal plants or substances derived from them are being tested as a tool for preventing infectious diseases such as IB in many countries, but the anti-IBV viral properties of the selected plants have not so far been tested. The objective of this study was to investigate extracts of 15 selected medicinal plants for anti-IBV activity.
Results
Cytotoxicity of plant extracts
All the extracts were more cytotoxic (
P < 0.05) than the ethanol control (7.7 μl).
A. foeniculum showed the highest cytotoxic concentration (0.062 μg) and
P. frutescens (0.77 μg) showed the lowest one.
Antiviral effect against IBV
According to the results of the antiviral effect assay, eight extracts were selected for determination of the virucidal effect. The selected extracts of
S. montana, O. vulgare,
M. piperita, M. officinalis, T. vulgaris, H. officinalis, S. officinalis and
D. canadense showed anti-IBV activity in two of the four methods. All eight extracts showed an antiviral effect prior to infection (method 1). Furthermore, seven of these showed antiviral activity during infection (method 2), while only the extract of
S. montana showed anti-IBV activity after infection (method 4).
P. frutescens,
N. cataria,
E. purpurea,
Ch. nobile and
A. foeniculum showed an antiviral effect only in the first method, while
G. macrorrhizum and
A. archangelica did not show an antiviral effect in any method (Table
1).
https://bmcvetres.biomedcentral.com/articles/10.1186/s12917-019-1925-6
