Omicron Variant of SARS-CoV-2: Dec. 1, 2021 update

Moving Simulation of SARS-CoV-2 Delta Variant

Image:  Computer Simulation of SARS-CoV-2. Reprinted with kind permission of Janet Iwasa of http://animationlab.utah.edu/cova

From Dec. 1, 2021

The CDC confirmed today the first case of the Omicron variant, which is officially known as B1.1.529,  in the United States.  The most concerning aspect of this new variant is the number of mutations associated with it.  Viruses are not living organisms; they require a host to continue or survive. The more hosts that viruses can find, the more likely they are to mutate further and potentially become more harmful to the hosts. Viruses cannot replicate on their own.  Instead they capture or “hijack” the reproductive mechanism in the host cell, redirect it to copy the genetic code of the virus, and seal it in a packet called a capsid. In a single human being, there can be a billion or even a trillion copies of the SARS-CoV-2 virus. Most of the time, these mutations or mistakes involve different amino acid sequences that may give rise to different proteins but do not enhance the ability of the virus to infect or replicate any better than the original copy. Occasionally, a mutation will increase infectivity and may, or may not, code for a new protein that the immune system fails to recognize.

The spike protein on SARS-CoV-2 interacts specifically with the ACE2 receptor, which is found on the surface of our cells mainly in the GI tract, the respiratory tract, and our vasculature. When the new  viral particles are created, they may have slightly different proteins either inside or outside the viral particle.  Of particular interest, the mutation may exist on the outer tip of the spike protein, which is called the receptor binding domain (RBD).  Our immune system recognizes the SARS-CoV-2 based on the RBD. Thus any mutation that changes the proteins in areas that make it easier for the virus to bind to our cells’ receptors or evade detection by the immune system will be advantageous to virus survival.

Let’s compare Omicron to two prior variants:  Alpha and Delta.  As to the virus particle itself, Alpha had 23 mutations, Delta had 17 mutations, and Omicron has 50 mutations.  As to the spike protein, Alpha had 9 mutations, Delta had 7 mutations, and Omicron has 32 mutations. As to the RBD, Alpha had 1 mutation, Delta had 2 mutations, and Omicron has 10 mutations.  The number and variety of mutations associated with the Omicron variant deserves serious concern.

Variants

Alpha Delta Omicron

Virus

23 mutations 17 mutations 50 mutations
Spike 9 mutations 7 mutations

32 mutations

RBD 1 mutation 2 mutations

10 mutations

Scientists are now focused on three questions: (1) what is the transmissibility of the Omicron variant?, (2) how well does it evade our current COVID-19 vaccines?, and (3) is there a change in the virulence (the variant is more deadly)?

 

From July 24, 2021

  • The Delta variant (B.1.617.2) has proven to be more contagious than the original SARS-CoV-2 (R0 = 3.5–4.5 vs R0 ~ 2.5) perhaps through better binding or better evasion of the immune system. (The spike protein of SARS-CoV-2 is coated with sugar molecules, or glycans, that help it evade the immune system.) The REACT-1 round 12 report (Imperial College London) found the Delta variant prevalence in those aged 5–49 was 2.5 times higher at 0.20% (0.16%, 0.26%) compared with those aged 50 years and above at 0.08% (0.06%, 0.11%). While people over age 50 may have higher vaccination rates, the Delta variant may pose a higher risk of infection for younger-aged individuals. As to hospitalization, The Lancet published correspondence (June 26, 2021) on a study in Scotland that the Delta variant had a 1.85 times higher risk of getting the person infected admitted to the hospital with severe COVID-19 [hazard ratio 1.85 (95% CI 1.39–2.47)].  The Scottish study used Reverse Transcription Polymerase Chain Reaction (RT-PCR) tests and a Cox regression analysis, which adjusts for age, sex, economic status/deprivation, temporal trend, and comorbidities.
  • As of July 2021, the Pfizer-BioNTech vaccine was shown to be effective against the Delta variant symptomatic infection at 88% (UK study), 87% (Canadian study), 64% (Israeli study), 79% (Scottish study), and effective against the Delta variant resulting in hospitalization at 96% (UK study) and 98% (Israeli study). The data for the Moderna vaccine are more limited and show the vaccine is 72% effective against symptomatic infection and 96% effective against hospitalization for the Delta variant after just the first dose of the two-dose vaccine. The Oxford-Astrazeneca vaccine was found to be effective against the Delta variant at 60% (UK study), 67% (Canadian study for single dose), 60% (Scottish study) for symptomatic infection and 93% (UK study), 88% (Canadian study) effective against Delta variant hospitalization. For the J&J vaccine, real-world evidence on effectiveness against the Delta variant is not yet available; however, J&J’s internal lab study showed it was highly effective against the South African variant, which was most prevalent at the time, and that the antibody response to the Delta variant is even better: a very good antibody response to the Delta variant based on lab testing.

From May 27, 2021

For early-onset COVID-19 cases (positive COVID-19 test and at-risk for progression of the disease but not experiencing symptoms requiring hospital-ization): “The FDA has halted the distribution of Lilly’s combination of bamlanivimab and etesevimab in Arizona, California, Florida, Indiana, Oregon and Washington––all states where coronavirus variants from Brazil and South Africa account for more than 10% of those with the disease. The antibody combo had previously been paused in Illinois and Massachusetts.

Providers in those states should use Regeneron’s antibody treatment of casirivimab and imdevimab, as per the FDA. Lab studies have shown that option is more effective against the Brazilian (P.1) and South African (B.1.351) strains, according to the agency.” [https://www.fiercepharma.com/pharma/fda-halts-use-lilly-covid-19-antibody-treatment-6-states-where-variants-are-prevalent]

Timing is important: MABS are very good at stopping the virus outside the cells. Once the SARS-CoV-2 has infected the cells, antibodies are not able to neutralize the virus. The patient then needs cytotoxic T-cells.

Two randomized clinical trials of Vitamin D, one from India (SHADE study) and one from Spain (calcifediol study), have shown that Vitamin D supplementation definitely benefitted patients with COVID-19. Emerging evidence shows Vitamin D combined with either or both Vitamin K2 and Magnesium potentiates the benefits of Vitamin D. Source for K2 synergy: https://pubmed.ncbi.nlm.nih.gov/29138634/

QUERCETIN in combination with vitamins C and D, may exert a synergistic antiviral action. Source: https://journals.sagepub.com/doi/full/10.1177/1934578X20976293

N-ACETYL-CYSTEINE (NAC) (600 mg) has known antiviral and liver protective properties. One argument for use with COVID-19 is https://pubmed.ncbi.nlm.nih.gov/32780893/ and another https://pubmed.ncbi.nlm.nih.gov/24968347/ and https://pubmed.ncbi.nlm.nih.gov/9230243/

SLEEP (7 – 9 hours): antibody and immune response after (flu) vaccination is improved if the patient has had a good night’s sleep, particularly the hours of sleep before midnight (slow wave sleep). Optimal T-cell production for disease prevention also requires optimal sleep. Melatonin may help patients get to sleep and has anti-viral properties. https://pubmed.ncbi.nlm.nih.gov/32347747/ https://pubmed.ncbi.nlm.nih.gov/32768490/

At the early stages of COVID-19 infection, the innate immune system is responsible for attacking the virus (primarily using monocytes & natural killer cells) through production of Interferon (IFN). SARS-CoV-2 delays the body’s IFN response. Patients with severe disease had less type I IFN activity in their blood compared to patients with mild to moderate disease. (The innate immune system diminishes with aging.) Any method to enhance the innate immune response in the early course of the disease could limit progression of COVID-19. Sauna baths, hot water baths, and other sources of human hyperthermia can induce a tenfold increase IFN-gamma synthesis. https://pubmed.ncbi.nlm.nih.gov/3132509/ These results suggest that raising the core body temperature akin to a mild fever may stimulate the innate immune system (particularly if followed by a cold shower or rapid cooling) and thereby attenuate COVID-19.

From APRIL 2020

“To be clear, SARS-CoV-2 is not the flu. It causes a disease with different symptoms, spreads and kills more readily, and belongs to a completely different family of viruses. This family, the coronaviruses, includes just six other members that infect humans. Four of them—OC43, HKU1, NL63, and 229E—have been gently annoying humans for more than a century, causing a third of common colds. The other two—MERS and SARS (or “SARS-classic,” as some virologists have started calling it)—both cause far more severe disease. Why was this seventh coronavirus the one to go pandemic? Suddenly, what we do know about coronaviruses becomes a matter of international concern.” Why the Coronavirus Has Been So Successful, The Atlantic

This article was inspired by the work of Jon Barron shown here: https://www.jonbarron.org/colds-flus-infectious-diseases/using-anti-pathogens. To combat the coronavirus, I have stocked my medicine cabinet with the following anti-viral pathogen natural products. In addition to providing the names and doses of the products, after each one, I provide the ten most recent citations from PubMed.gov pertaining to that substance and viruses.

  1. AHCC (Active Hexose-Correlated Compound) – 500 mg, taken on an empty stomach up to four capsules per day at outset of symptoms
  2. Olive Leaf Extract (Olea europaea) (standardized to minimum 20% oleuropein) – 500 mg, taken with food once or twice per day.
  3. Oil of Oregano (Origanum vulgare) (leaf) (10:1 extract) – 150 mg, taken up to four gelcaps per day with water
  4. Star Anise Oil – 1 fluid oz, blended and diluted with extra virgin olive oil or extra virgin coconut oil
  5. Minced Garlic — 1 tbsp added to main meal

 

AHCC (Active Hexose-Correlated Compound)

“Mushrooms have been used for various health conditions for many years by traditional medicines practiced in different regions of the world although the exact effects of mushroom extracts on the immune system are not fully understood. AHCC® is a standardized extract of cultured shiitake or Lentinula edodes mycelia (ECLM) which contains a mixture of nutrients including oligosaccharides, amino acids, and minerals obtained through liquid culture. AHCC® is reported to modulate the numbers and functions of immune cells including natural killer (NK) and T cells which play important roles in host defense, suggesting the possible implication of its supplementation in defending the host against infections and malignancies via modulating the immune system. Here, we review in vivo and in vitro effects of AHCC® on NK and T cells of humans and animals in health and disease, providing a platform for the better understanding of immune-mediated mechanisms and clinical implications of AHCC®.” Shin MS, Park HJ, Maeda T, Nishioka H, Fujii H, Kang I. The Effects of AHCC®, a Standardized Extract of Cultured Lentinura edodes Mycelia, on Natural Killer and T Cells in Health and Disease: Reviews on Human and Animal Studies. J Immunol Res. 2019;2019:3758576. Published 2019 Dec 20. doi:10.1155/2019/3758576 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6942843/

Possible therapeutic role of a highly standardized mixture of active compounds derived from cultured Lentinula edodes mycelia (AHCC) in patients infected with 2019 novel coronavirus.

Di Pierro F, et al. Minerva Gastroenterol Dietol 2020. PMID 32162896
The outbreak of SARS-CoV-2 disease (COVID-19) is currently, March 2020, affecting more than 100000 people worldwide and, according to the WHO (World Health Organization), a pandemic is shortly expected. The virus infects the lower respiratory tract and causes severe pneumonia and mortality in approximately 10% and 3-5%, respectively, of cases, mainly among the elderly and/or people affected by other diseases. AHCC is an α-glucan-based standardized mushroom extract that has been extensively investigated as an immunostimulant both in animals and/or in humans affected by West Nile virus, influenza virus, avian influenza virus, hepatitis C virus, papillomavirus, herpes virus, hepatitis B virus and HIV by promoting a regulated and protective immune response. Although the efficacy of AHCC has not yet been specifically evaluated with respect to SARS-CoV-2 disease, its action in promoting a protective response to a wide range of viral infections, and the current absence of effective vaccines, could support its use in the prevention of diseases provoked by human pathogenic coronavirus, including COVID-19.

The prognostic factors between different viral etiologies among advanced hepatocellular carcinoma patients receiving sorafenib treatment.

Yeh ML, et al. Kaohsiung J Med Sci 2019. PMID 31254328 Free article.
Pre-treatment clinical data and viral hepatitis markers were collected and analyzed with their outcomes. The primary endpoint of the study was overall survival. …There were different prognostic factors stratified by viral etiologies in aHCC patients receiving sorafenib. Viral eradication increased survival in chronic hepatitis C patients….
Ito T, et al. Nutr Cancer 2014 – Clinical Trial. PMID 24611562
The objective of this study was to evaluate the safety and effectiveness of a mushroom product, active hexose correlated compound (AHCC), on chemotherapy-induced adverse effects and quality of life (QOL) in patients with cancer. Twenty-four patients with cancer received their first cycle of chemotherapy without AHCC and then received their second cycle with AHCC. …
Roman BE, et al. Nutr Res 2013 – Clinical Trial. PMID 23351405
In this study, we hypothesized that AHCC will also improve the immune responses of healthy individuals to influenza vaccine. …Immediately post-vaccination, the AHCC group began supplementation with AHCC (3 g/d). Flow cytometric analysis of lymphocyte subpopulations revealed that AHCC supplementation increased NKT cells (P < .1), and CD8 T cells (P < .05) post-vaccination compared to controls. …
Nogusa S, et al. Nutr Res 2009. PMID 19285605
We hypothesized that AHCC supplementation would influence the immune response to influenza infection in a dose-dependent manner. …In conclusion, these data suggest that the effects of AHCC on the immune response to influenza infection are dose dependent and that low-dose AHCC supplementation improves the response to influenza infection despite no effect on total NK cell cytotoxicity….
Wang S, et al. J Nutr 2009. PMID 19141700 Free PMC article.
AHCC administration in aged mice attenuated viremia levels but led to no difference in mortality rate. Overall, our data suggests that AHCC enhances protective host immune responses against WNV infection in young and aged mice. Dietary supplementation with AHCC may be potentially immunotherapeutic for WNV-susceptible populations….
Momiyama K, et al. Cancer Chemother Pharmacol 2009. PMID 19011857
CONCLUSIONS: The percentage of Th2 cells increased in LC patients with aHCC as the efficacy of intra-arterial combination chemotherapy decreased. These results indicated that intra-arterial chemotherapy might be not useful for patients with aHCC, because it induces Th2 dominant host immunity….

Th1/Th2 balance: an important indicator of efficacy for intra-arterial chemotherapy

Nagai H, et al. Cancer Chemother Pharmacol 2008. PMID 18259753
The aim of this study was to assess the influence of intra-arterial combination chemotherapy on the Th1/Th2 balance in LC patients with aHCC. …RESULTS: Thirteen of the 21 aHCC patients (group R) showed an objective response, but the other 8 patients (group N) showed no response. …
Ritz BW, et al. J Nutr 2006. PMID 17056815
However, the effects of AHCC on the response to viral infections have not been studied. In this study, young C57BL/6 mice were supplemented with 1 g AHCC/(kg body weight x d) for 1 wk prior to and throughout infection with influenza A (H1N1, PR8). …These data suggest that AHCC supplementation boosts NK activity, improves survival, and reduces the severity of influenza infection in young mice. …

 

OLIVE LEAF EXTRACT

“The olive tree (Olea europaea) is native to the Mediterranean region. Olive leaf extract has a long history of use against illnesses in which microorganisms play a major role. In more recent years, studies of olive leaf extracts (containing oleuropein, calcium elenolate, and/or hydroxytyrosol) were effective in eliminating a very broad range of organisms, including bacteria, viruses, parasites, yeast, mold, and fungi.25 Pio Maria Furneri, Anna Piperno, Antonella Sajia, and Giuseppe. “Antimycoplasmal Activity of Hydroxytyrosol, Antimicrob Agents.” Chemother. 2004 December; 48(12): 4892–4894. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC529223/ , 26 Harold E. Renis. “Inactivation of Myxoviruses by Calcium Elenolate.” Antimicrobial Agents and Chemotherapy Aug. 1975, p. 194-199. http://aac.asm.org/cgi/reprint/8/2/194.pdf In addition, Olive leaf has demonstrated antiviral activity against both HIV infection and replication,27 Lee-Huang S1, Zhang L, Huang PL, Chang YT, Huang PL. “Anti-HIV activity of olive leaf extract (OLE) and modulation of host cell gene expression by HIV-1 infection and OLE treatment.” Biochem Biophys Res Commun. 2003 Aug 8;307(4):1029-37. http://www.ncbi.nlm.nih.gov/pubmed/12878215 primarily by blocking the entry of the virus into host cells in the body’s immune system.28 Bao J1, Zhang DW, Zhang JZ, Huang PL, Huang PL, Lee-Huang S. “Computational study of bindings of olive leaf extract (OLE) to HIV-1 fusion protein gp41.” FEBS Lett. 2007 Jun 12;581(14):2737-42. http://www.ncbi.nlm.nih.gov/pubmed/17537437

Studies have also shown that oleuropein exhibits a significant antiviral activity against respiratory syncytial virus and para-influenza type 3 virus.29 Ma SC, He ZD, Deng XL, But PP, et al. “In vitro evaluation of secoiridoid glucosides from the fruits of Ligustrum lucidum as antiviral agents.” Chem Pharm Bull. 2001;49:1471–1473. http://www.jstage.jst.go.jp/article/cpb/49/11/49_11_1471/_pdf In addition, it has been found to be effective against viral hemorrhagic septicemia rhabdovirus, a highly deadly and infectious virus that afflicts over 50 species of both freshwater and marine water fish. 30 Micol V, Caturla N, Perenz-Fons L, Mas L, Perez L, Estepa A. “The olive leaf extract exhibits antiviral activity against viral haemorrhagic septicaemia rhabdovirus (VHSV)” Antivir Res. 2005;66:129–136. http://www.ncbi.nlm.nih.gov/pubmed/15869811 There are studies that demonstrate that olive leaf extracts augment the activity of the HIV-RT inhibitor 3TC. In fact, cell-to-cell transmission of HIV was inhibited in a dose-dependent manner, and replication was inhibited in an in vitro experiment.31 Lee-Huang S, Zhang L, Chang YY, Huang PL. “Anti-HIV activity of olive leaf extract (OLE) and modulation of host cell gene expression by HIV-1 infection and OLE treatment.” Biochem Biophys Res Commun. 2003;307:1029–1037. http://www.ncbi.nlm.nih.gov/pubmed/12878215 One of the suspected targets for olive leaf extract action is the HIV-1 gp41 (surface glycoprotein subunit), which is responsible for HIV entry into normal cells. In order to establish HIV protein targets of olive leaf extract and its inhibitory action at the molecular level, researchers reported a joint theoretical and experimental effort has been carried out to help achieve this goal.32 Lee-Huang S, Huang PL, Zhang D, Lee JW, Bao J, et al. “Discovery of small-molecule HIV-1 fusion and integrase inhibitors oleuropein and Hydroxytyrosol: Part I.” Integrase Inhibition Biochem Biophys Res Commun. 2007;354:872–878. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2790717/

Source: Jon Barron, Using Anti-Pathogens

[Comparison of Antiviral Effect of Olive Leaf Extract and Propolis with Acyclovir on Herpes Simplex Virus Type 1].

Altındiş M, et al. Mikrobiyol Bul 2020. PMID 32050880 Turkish. Free article.
In this in vitro study, olive leaf extract (OLE) and propolis alone or in combination with acyclovir were investigated for their antiviral efficacy in HSV-1.Toxic doses of OLE, propolis, and dimethyl sulfoxide, propolis diluent, for Hep-2 (ATCC, CCL-23) cells were determined by conventional cell culture. Using “endpoint” method, the viral dose infecting half of the cell culture (TCID50) was calculated, and viral quantity was determined with Spearman-Karber method. …

 

Oil of Oregano

Antifungal Activity of Selected Natural Preservatives against Aspergillus westerdijkiae and Penicillium verrucosum and the Interactions of These Preservatives with Food Components

Schlösser I and Prange A. J Food Prot 2019. PMID 31538828
The present study examined the influence of primary food components on the antifungal activity of the essential oil of Origanum vulgare, carvacrol, thymol, eugenol, and trans-cinnamaldehyde against Penicillium verrucosum and Aspergillus westerdijkiae. …The presence of oil had the strongest influence. At a concentration of 1% oil, the antifungal activity decreased significantly, and at 10% oil, almost no inhibition was observed. …

Star Anise Oil (Pimpinella Anisum)

[Potential antiviral therapeutics for 2019 Novel Coronavirus]

Li H, et al. Zhonghua Jie He He Hu Xi Za Zhi 2020. PMID 32164080 Chinese.
Antiviral drugs commonly used in clinical practice, including neuraminidase inhibitors (oseltamivir, paramivir, zanamivir, etc.), ganciclovir, acyclovir and ribavirin, are invalid for 2019-nCoV and not recommended. …

Screening for antiviral activities of isolated compounds from essential oils

Astani A, et al. Evid Based Complement Alternat Med 2011.
Essential oil of star anise as well as phenylpropanoids and sesquiterpenes, for example, trans-anethole, eugenol, β-eudesmol, farnesol, β-caryophyllene and β-caryophyllene oxide, which are present in many essential oils, were examined for their antiviral activity against herpes simplex virus type 1 (HSV-1) in vitro. Antiviral activity was analyzed by plaque reduction assays and mode of antiviral action was determined by addition of the drugs to uninfected cells, to the virus prior to infection or to herpesvirus-infected cells. Star anise oil reduced viral infectivity by >99%, phenylpropanoids inhibited HSV infectivity by about 60-80% and sesquiterpenes suppressed herpes virus infection by 40-98%. Both, star anise essential oil and all isolated compounds exhibited anti-HSV-1 activity by direct inactivation of free virus particles in viral suspension assays. All tested drugs interacted in a dose-dependent manner with herpesvirus particles, thereby inactivating viral infectivity. Star anise oil, rich in trans-anethole, revealed a high selectivity index of 160 against HSV, whereas among the isolated compounds only β-caryophyllene displayed a high selectivity index of 140. The presence of β-caryophyllene in many essential oils might contribute strongly to their antiviral ability. These results indicate that phenylpropanoids and sesquiterpenes present in essential oils contribute to their antiviral activity against HSV.

Chemical Constituents of Essential Oils Possessing Anti-Influenza A/WS/33 Virus Activity

Choi HJ. Osong Public Health Res Perspect 2018. PMID 30584499 Free PMC article.
The chemical composition detected by GC-MS analysis, differed amongst the 3 most potent anti-viral essential oils (marjoram, clary sage and anise oils) except for linalool, which was detected in all 3 essential oils. CONCLUSION: This study demonstrated anti-influenza activity in 11 essential oils tested, with marjoram, clary sage and anise essential oils being the most effective at reducing visible cytopathic effects of the A/WS/33 virus. …

Antiviral and immunostimulating effects of lignin-carbohydrate-protein complexes from Pimpinella anisum.

Lee JB, et al. Biosci Biotechnol Biochem 2011. PMID 21389629 Free article.
Three antiviral and immunostimulating substances (LC1, LC2 and LC3) were isolated from a hot water extract of seeds of Pimpinella anisum by combination of anion-exchange, gel filtration and hydrophobic interaction column chromatographies. …

Efficacy of anise oil, dwarf-pine oil and chamomile oil against thymidine-kinase-positive and thymidine-kinase-negative herpesviruses.

Koch C, et al. J Pharm Pharmacol 2008. PMID 18957177
The effect of anise oil, dwarf-pine oil and chamomile oil against different thymidine-kinase-positive (aciclovir-sensitive) and thymidine-kinase-negative (aciclovir-resistant) herpes simplex virus type 1 (HSV-1) strains was examined. …No significant effect on viral infectivity could be achieved by adding these compounds during the replication phase. These results indicate that anise oil, dwarf-pine oil and chamomile oil affected the virus by interrupting adsorption of herpesviruses and in a different manner than aciclovir, which is effective after attachment inside the infected cells. …

Inhibitory effect of essential oils against herpes simplex virus type 2

Koch C, et al. Phytomedicine 2008. PMID 17976968
In order to determine the mode of the inhibitory effect, essential oils were added at different stages during the viral infection cycle. …These results indicate that essential oils affected HSV-2 mainly before adsorption probably by interacting with the viral envelope. …

 

Garlic

Garlic for the common cold.

Lissiman E, et al. Cochrane Database Syst Rev 2014 – Review. PMID 25386977 Free PMC article.
Background Garlic is alleged to have antimicrobial and antiviral properties that relieve the common cold, among other beneficial effects. …The trial reported 24 occurrences of the common cold in the garlic intervention group compared with 65 in the placebo group (P value < 0.001), resulting in fewer days of illness in the garlic group compared with the placebo group (111 versus 366). …

The effect of Allium sativum (Garlic) extract on infectious bronchitis virus in specific pathogen free embryonic egg.

Mohajer Shojai T, et al. Avicenna J Phytomed 2016. PMID 27516987 Free PMC article.
This study evaluated the inhibitory effects of garlic extract on IBV. MATERIALS AND METHODS: The constituents of garlic extract were detected by gas chromatography. …CONCLUSION: The garlic extract had inhibitory effects on IBV in the chickens embryo….
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