Quantification of HBsAg:Basic virology for clinical practice

Hepatitis B surface antigen (HBsAg) is produced and secreted through a complex mechanism that is still not fully understood. In clinical fields, HBsAg has long served as a qualitative diagnostic marker for hepatitis B virus infection. Notably, advances have been made in the development of quantitative HBsAg assays, which have allowed viral replication monitoring, and there is an opportunity to make maximal use of quantitative HBsAg to elucidate its role in clinical fields. Yet, it needs to be underscored that a further understanding of HBsAg, not only from clinical point of view but also from a virologic point of view, would enable us to deepen our insights, so that we could more widely expand and apply its utility. It is also important to be familiar with HBsAg variants and their clinical consequences in terms of immune escape mutants, issues resulting from overlap with corresponding mutation in the P gene, and detection problems for the HBsAg variants. In this article, we review current concepts and issues on the quantification of HBsAg titers with respect to their biologic nature, method principles, and clinically relevant topics.

Scotomas in molecular virology and epidemiology of hepatitis C virus

In the 1970s,scientists learned of a new pathogen causing non-A,non-B hepatitis.Classical approaches were used to isolate and characterize this new pathogen,but it could be transmitted experimentally only to chimpanzees and progress was slow until the pathogen was identified as hepatitis C virus(HCV)in 1989.Since then,research and treatment of HCV have expanded with the development of modern biological medicine:HCV genome organization and polyprotein processing were delineated in 1993;the first three-dimensional structure of HCV nonstructural protein(NS3 serine protease)was revealed in 1996;an infectious clone of HCV complementary DNA was first constructed in 1997;interferon and ribavirin combination therapy was established in 1998 and the therapeutic strategy gradually optimized;the HCV replicon system was produced in1999;functional HCV pseudotyped viral particles were described in 2003;and recombinant infectious HCV in tissue culture was produced successfully in 2005.Recently,tremendous advances in HCV receptor discovery,understanding the HCV lifecycle,decryption of the HCV genome and proteins,as well as new anti-HCV compounds have been reported.Because HCV is difficult to isolate and culture,researchers have had to avail themselves to the best of modern biomedical technology;some of the major achievements in HCV research have not only advanced the understanding of HCV but also promoted knowledge of virology and cellular physiology.In this review,we summarize the advancements and remaining scotomas in the molecular virology and epidemiology of HCV.

Medical Virology in Malaysia

Virology is a branch of biological science dealing with the study of viruses,and medical virology focuses on the study and control of diseases due to viruses that is of medical importance. The development of medical virology in Malaysia has its beginning in the Institute for Medical Research(IMR) ,following the establishment of the Division of Medical Zoology and Virus Research in the institute on 23 March 1953. The second institution in the country to establish diagnostic and research work in medical virology was Department of Medical Microbiology,Faculty of Medicine,University Malaya. This was followed by University Kebangsaan Malaysia,University Sains Malaysia and University of Sarawak Malaysia. The National Public Health Laboratory(NPHL) is the latest institution to establish a laboratory in 2003 for virus isolation and services to support country surveillance and outbreak investigation of infectious diseases due to viruses. In the field of medical virology,Malaysia contributed substantially in the areas of virus diagnostic services,development and research ranging from survey and documentation on the existence and prevalence of viruses causing diseases in Malaysia,clinical presentation and epidemiological features of virus diseases,evaluation of new diagnostic tests to pathogenesis of viral diseases. Malaysia contributed to the discoveries of at least 12 new viruses in the world. ASEAN plus Three(China,Japan,Republic of Korea) Emerging Infectious Programme was established to overcome the challenges and impact of emerging and re-emerging infectious diseases in this region. Malaysia as the co-ordinator of the laboratory component of the programme,contributed to strengthen the regional laboratory capability,capacity,laboratory-based surveillance and networking. The future of medical virology in Malaysia in terms of integration of diagnostic,reference and research to support the country's need will be enhanced and strengthened with the on-going development of the National Centre for Disease Control and Prevention(CDC Malaysia) which also incorporates a futuristic Special Diagnostic and Reference Laboratory.

New Year’s greeting and overview of World Journal of Virology in 2021

The 2020 year-end wrap-up session of Baishideng Publishing Group was held on December 31,2020.All staff attended this session.We shared our key results area and made a business plan regarding the journal management.World Journal of Virology(WJV)is now abstracted and indexed in PubMed and PubMed Central.It received 23 manuscripts and published 9 papers which included 6 articles reporting coronavirus 19 in 2020.On the other hand,we made major strategies for WJV’s development in 2021.At present,WJV only has 28 Editorial Board members and cannot receive many manuscripts.We must redouble our efforts to invite more highly influential scientists to join our Editorial Board member and write high-quality manuscripts.

Inhibition of EGFR attenuates EGF-induced activation of retinal pigment epithelium cell via EGFR/AKT signaling pathway

AIM:To explore the effect of epidermal growth factor receptor(EGFR)inhibition by erlotinib and EGFR siRNA on epidermal growth factor(EGF)-induced activation of retinal pigment epithelium(RPE)cells.METHODS:Human RPE cell line(ARPE-19 cells)was activated by 100 ng/mL EGF.Erlotinib and EGFR siRNA were used to intervene EGF treatment.Cellular viability,proliferation,and migration were detected by methyl thiazolyl tetrazolium(MTT)assay,bromodeoxyuridine(BrdU)staining assay and wound healing assay,respectively.EGFR/protein kinase B(AKT)pathway proteins and N-cadherin,α-smooth muscle actin(α-SMA),and vimentin were tested by Western blot assay.EGFR was also determined by immunofluorescence staining.RESULTS:EGF treatment for 24h induced a significant increase of ARPE-19 cells’viability,proliferation and migration,phosphorylation of EGFR/AKT proteins,and decreased total EGFR expression.Erlotinib suppressed ARPE-19 cells’viability,proliferation and migration through down regulating total EGFR and AKT protein expressions.Erlotinib also inhibited EGF-induced an increase of proliferative and migrative ability in ARPE-19 cells and clearly suppressed EGF-induced EGFR/AKT proteins phosphorylation and decreased expression of N-cadherin,α-SMA,and vimentin proteins.Similarly,EGFR inhibition by EGFR siRNA significantly affected EGF-induced an increase of cell proliferation,viability,and migration,phosphorylation of EGFR/AKT proteins,and up-regulation of N-cadherin,α-SMA,and vimentin proteins.CONCLUSION:Erlotinib and EGFR-knockdown suppress EGF-induced cell viability,proliferation,and migration via EGFR/AKT pathway in RPE cells.EGFR inhibition may be a possible therapeutic approach for proliferative vitreoretinopathy(PVR).

STUDY ON VIROLOGY OF EXPERIMENTAL LEUKEMIA IN CHINA

Since 1960, the Department of Pathophysio-logy of Shanghai Medical University has beenstudying the virology of experimental leukemia,the strains of L6565 mouse viral leukemia, SRSascitic and solid lymphoma and L783 transplan-table leukemia were established successively. Allof these tumor strains originated from the spon-taneous lymphocytic leukemia of Kunmin mouse(Figure 1). Type A and type C virus particlescould be observed in ultrathin sections of thymus,spleen and lymphonode of all these strains mouse

A Brief Analysis of Syntactical Features of English Virology Texts

Ever since late 2019,the COVID pandemic has given the world a great deal of pain and financial loss.Virologists around the world are working hard to eradicate it.Vaccines and treatment methods have been found,which cannot be accomplished without the joint efforts of the world virologist community.Naturally,facilitating global communication would help advance the research.This paper analyzes syntactical features of English virology texts and finds that:In these texts,verbs and postpositive attributes are used frequently,complicated logic needs careful analysis,and personification is often used.Having some knowledge of these sentence features may contribute to better communication in the virology community.

A Brief Analysis of Lexical Features of English Virology Texts

COVID has already been taken as a global pandemic,the culprit of which is the virus called SARS-CoV-2.Virologists around the world have been working hard at trying to find remedies and protection methods for the world.This paper is a brief analysis of lexical features of English virology texts,which will show that technical words,semi-technical words,and acronyms are the three prominent lexical features of English virology tests.It may be helpful in guiding cross-language communication in the virologists’community,which the authors hope would facilitate global research on COVID.

INSTITUTE OF VIROLOGY CHINESE ACADEMY OF PREVENTIVE MEDICINE

The Institute of Virology was established in 1964. Its precursor was the Laboratory of Virology, Department of Microbiology, Chinese Academy of Medical Sciences (1949-1955), which was subsequently expanded to become the Department of Virology (1956-1963). This Institute has a total of around 350 staff and 11 departments, namely, the Departments of Hepatitis Viruses, Epidemic Hemorrhagic Fever Viruses, Arboviruses, Influenza Viruses, Viral Immunology, Viral Genetics, Viral Diagnosis, Viral Oncology, Viral Morphology, Viral Biological Product Development, and the National Laboratory of Molecular Virology and Genetic Engineering. It acts as the

RNA-sequencing expression profile and functional analysis of retinal pigment epithelium in atrophic age-related macular degeneration

The retinal pigment epithelium(RPE)is fundamental to sustaining retinal homeostasis.RPE abnormality leads to visual defects and blindness,including age-related macular degeneration(AMD).Although breakthroughs have been made in the treatment of neovascular AMD,effective intervention for atrophic AMD is largely absent.The adequate knowledge of RPE pathology is hindered by a lack of the patients'RPE datasets,especially at the single-cell resolution.In the current study,we delved into a large-scale single-cell resource of AMD donors,in which RPE cells were occupied in a substantial proportion.Bulk RNA-seq datasets of atrophic AMD were integrated to extract molecular characteristics of RPE in the pathogenesis of atrophic AMD.Both in vivo and in vitro models revealed that carboxypeptidase X,M14 family member 2(CPXM2),was specifically expressed in the RPE cells of atrophic AMD,which might be induced by oxidative stress and involved in the epithelial-mesenchymal transition of RPE cells.Additionally,silencing of CPXM2 inhibited the mesenchymal phenotype of RPE cells in an oxidative stress cell model.Thus,our results demonstrated that CPXM2 played a crucial role in regulating atrophic AMD and might serve as a potential therapeutic target for atrophic AMD.

Effect of acetyl L-carnitine on human retinal pigment epithelium-19 cells in hypoxic conditions

AIM:To investigate the effect of acetyl-L-carnitine(ALCAR)on cell viability,morphological integrity,and vascular endothelial growth factor(VEGF)expression in human retinal pigment epithelium(ARPE-19)cells using a hypoxic model.METHODS:In the first set of experiments,the optimal CoCl_(2) dose was determined by exposing ARPE-19 cell cultures to different concentrations.To evaluate the effect of ALCAR on cell viability,five groups of ARPE-19 cell culture were established that included a control group,a sham group(200μM CoCl_(2)),and groups that received 1,10 and 100 mM doses of ALCAR combined with 200μM CoCl_(2),respectively.The cell viability was measured by MTT assay.The morphological characteristics of cells were observed by an inverted phase contrast microscope.The levels of VEGF and HIF-1α secretion by ARPE-19 cells were detected by enzyme linked immunosorbent assay(ELISA)assay.RESULTS:ARPE-19 cells were exposed to different doses of CoCl_(2) in order to create a hypoxia model.Nevertheless,when exposed to a concentration of 200μM CoCl_(2),a notable decrease in viability to 83% was noted.ALCAR was found to increase the cell viability at 1 mM and 10 mM concentrations,while the highest concentration(100 mM)did not have an added effect.The cell viability was found to be significantly higher in the groups treated with a concentration of 1 mM and 10 mM ALCAR compared to the Sham group(P=0.041,P=0.019,respectively).The cell viability and morphology remained unaffected by the greatest dose of ALCAR(100 mM).The administration of 10 mM ALCAR demonstrated a statistically significant reduction in the levels of VEGF and HIF-1α compared with the Sham group(P=0.013,P=0.033,respectively).CONCLUSION:The findings from the current study indicate that ALCAR could represent a viable therapeutic option with the potential to open up novel treatment pathways for retinal diseases,particular relevance for age-related macular degeneration(AMD).However,to fully elucidate ALCAR’s application potential in retinal diseases,additional investigation is necessary to clearly define the exact mechanisms involved.

INSTITUTE OF VIROLOGY CHINESE ACADEMY OF PREVENTIVE MEDICINE

The Institute of Virology was established in 1964. Its precursor was the Laboratory of Virology, Department of Microbiology, Chinese Academy of Medical Sciences (1949-1955), which was subsequently expanded to become the Department of Virology (1956-1963). This Institute has a total of around 350 staffand 11 departments, namely,

Expression of HMGB1 Protein in Human Cervical Squamous Epithelium Carcinoma

OBJECTIVE To investigate the expression of the high mobility group boxl（HMGB1） in human cervical squamous epithelial carcinoma （CSEC） and to explore the relationship of HMGB1 expression to the differentiation degree, size, invasion and metastasis of CSEC. METHODS Immunohistochemical staining of tissue microarrays and Western blot analysis were conducted to detect the expression of HMGB1 in the following tissue samples： 30 carcinoma in situ, 90 invasive CSEC without metastasis, 30 invasive CSEC with metastasis, 30 cases of normal cervical squamous epithelia. RESULTS The positive-expression rate of HMGB1 was 58.7% （88/150） in CSEC, showing a significant difference compared to normal cervical squamous epithelia. The expression of HMGB1 was correlated with tumor size, invasion and metastasis of CSEC （respectively, P〈0.01）, but had no relationship with the degree of differentiation （P〉0.05）. CONCLUSION The over-expression of HMGB1 in CSEC might be a useful parameter as an indication of tumor invasion, metastasis, prognosis and overall biological behavior of human CSEC, as well as a noval target site for gene therapy.

Cortical hem signaling center: functions, development, and potential implications for evolution and brain disorders

Development of the telencephalon relies upon several signaling centers-localized cellular populations that supply secreted factors to pattern the cortical neuroepithelium.One such signaling center is the cortical hem,which arises during embryonic development at the telencephalic dorsal midline,adjacent to the choroid plexus and hippocampal primordium(Figure 1A).While the cortical hem has also been described in reptiles and birds,most of our knowledge about the developmental roles of the cortical hem is derived from the analysis in mice.The cortical hem produces several types of secreted molecules,including wingless-related integration site(Wnt)and bone morphogenetic(Bmp)proteins.The cortical hem is particularly important for the development of the hippocampus,which is involved in learning and memory,and the neocortex,which is the most complex brain region that mediates multiple types of behavior and higher cognitive functions(Mangale et al.,2008;Dal-Valle-Anton and Borrell,2022).

雄鱼性腺发育的组织学观察研究进展及生殖上皮(Germinal Epithelium)的作用

本文综述了近几年雄鱼性腺发育组织学观察方面的研究进展。对于已达性成熟年龄的雄鱼,借助于对精巢中生殖上皮的动态变化的研究,可更准确地评估精巢发育的周年性改变程度,更好地理解精巢内部有丝分裂和减数分裂作用互为主次,互相转变的过程。使用"生殖上皮"这一概念,一定程度上将鱼纲和鸟纲,哺乳纲的性腺发育统一起来,便于比较它们的异同。总的来说,生殖上皮在鱼类性腺发育中的作用,值得进行更深入的研究。

Serum hepatitis B virus RNA is a predictor of HBeAg seroconversion and virological response with entecavir treatment in chronic hepatitis B patients

BACKGROUND Characteristics of alterations of serum hepatitis B virus(HBV) RNA in different chronic hepatitis B(CHB) patients still cannot be fully explained. Whether HBV RNA can predict HBeAg seroconversion is still controversial.AIM To investigate whether HBV RNA can predict virological response or HBeAg seroconversion during entecavir(ETV) treatment when HBV DNA is undetectable.METHODS The present study evaluated 61 individuals who were diagnosed and treated with long-term ETV monotherapy at the Department of Infectious Diseases of Peking University First Hospital(China) from September 2006 to December 2007.Finally, 30 treatment-naive individuals were included. Serum HBV RNA were extracted from 140 μL serum samples at two time points. Then they were reverse transcribed to cDNA with the HBV-specific primer. The product was quantified by real-time quantitative PCR(RT-PCR) using TAMARA probes. Statistical analyses were performed with IBM SPSS 20.0.RESULTS Level of serum HBV RNA at baseline was 4.15 ± 0.90 log10 copies/mL. HBV RNA levels showed no significant difference between the virological response(VR)and partial VR(PVR) groups at baseline(P = 0.940). Serum HBV RNA significantly decreased among patients who achieved a VR during ETV therapy(P < 0.001). The levels of HBV RNA in both HBeAg-positive patients with seroconversion group and those with no seroconversion increased after 24 wk of treatment. Overall, HBV RNA significantly but mildly correlated to HBsAg(r =0.265, P = 0.041), and HBV RNA was not correlated to HBV DNA(r = 0.242, P =0.062). Furthermore, serum HBV RNA was an independent indicator for predicting HBeAg seroconversion and virological response. HBeAg seroconversion was more likely in CHB patients with HBV RNA levels below4.12 log10 copies/mL before treatment.CONLUSION The level of serum HBV RNA could predict HBeAg seroconversion and PVR during treatment. In the PVR group, the level of serum HBV RNA tends to be increasing.

Fatty liver in hepatitis C patients post-sustained virological response with direct-acting antivirals

AIM To determine steatosis and fibrosis prevalence in hepatitis C patients after a sustained virological response achieved with direct-acting antivirals.METHODS Transient elastography with controlled attenuation parameter(CAP) was used to assess hepatic steatosis post-sustained virological response(SVR);the CAP technology was not available in the United States at study initiation.Liver stiffness/fibrosis was measured before and 47 wk after treatment completion.Patients with genotype 3 and patients with cirrhosis were excluded.RESULTS One hundred and one patients were included in the study.Post-SVR there were decreases from baseline in alanine aminotransferase(ALT)(63.1 to 17.8 U/L),aspartate aminotransferase(51.8 to 21.5 U/L) and fibrosis score(7.4 to 6.1 k Pa)(P < 0.05).Post-SVR,48 patients(47.5%) had steatosis on CAP;of these,6.25% had advanced fibrosis.Patients with steatosis had higher body mass index(29.0 vs 26.1 kg/m2),glucose(107.8 vs 96.6 mg/d L),ALT(20.4 vs 15.3 mg/d L),CAP score(296.3 vs 212.4 d B/m) and fibrosis score(7.0 vs 5.3 k Pa);P < 0.05.Interestingly,compared to baseline,both patients with and without steatosis had change in fibrosis score post-SVR(7.7 k Pa vs 7.0 k Pa and 7.0 k Pa vs 5.3 k Pa);alternatively,(P < 0.05) and therefore patients with steatosis continued to have clinically significant stiffness(≥ 7 k Pa).CONCLUSION Fatty liver is very common in hepatitis C virus(HCV) patients post-SVR.These patients continue to have elevated mean fibrosis score(≥ 7 k Pa) compared to those without fatty liver;some have advanced fibrosis.Long term follow up is needed to assess steatosis and fibrosis in HCV patients post-SVR.

Sustained virologic response to direct-acting antiviral agents predicts better outcomes in hepatitis C virus-infected patients: A retrospective study

BACKGROUND Direct-acting antiviral agents(DAAs)are extremely effective in eradicating hepatitis C virus(HCV)in chronically infected patients.However,the protective role of the sustained virologic response(SVR)achieved by second-and thirdgeneration DAAs against the onset of hepatocellular carcinoma(HCC)and mortality is less well established.AIM To examine the occurrence of HCC or death from any cause in a retrospectiveprospective study of patients treated with DAAs.METHODS Patients were enrolled from a tertiary academic hospital center for liver disease management that collects subject data mainly from northeastern Italy.The study was conducted in 380 patients(age:60±13 years,224 males,32%with cirrhosis)treated with DAAs with or without SVR(95/5%),with a median follow up of 58 wk(interquartile range:38-117).The baseline anthropometric features,HCV viral load,severity of liver disease,presence of extra-hepatic complications,coinfection with HIV and/or HBV,alcohol consumption,previous interferon use,alphafetoprotein levels,and renal function were considered to be confounders.RESULTS The incidence rate of HCC in patients with and without SVR was 1.3 and 59 per 100 person-years,respectively(incidence rate ratio:44,95%CI:15-136,P<0.001).Considering the combined endpoint of HCC or death from any cause,the hazard ratio(HR)for the SVR patients was 0.070(95%CI:0.025-0.194,P<0.001).Other independent predictors of HCC or death were low HCV viremia(HR:0.808,P=0.030),low platelet count(HR:0.910,P=0.041),and presence of mixed cryoglobulinemia(HR:3.460,P=0.044).Considering SVR in a multi-state model,the independent predictors of SVR achievement were absence of cirrhosis(HR:0.521,P<0.001)and high platelet count(HR:1.019,P=0.026).Mixed cryoglobulinemia predicted the combined endpoint in patients with and without SVR(HR:5.982,P=0.028 and HR:5.633,P=0.047,respectively).CONCLUSION DAA treatment is effective in inducing SVR and protecting against HCC or death.A residual risk of HCC persists in patients with advanced liver disease or with complications,such as mixed cryoglobulinemia or renal failure.

Effect of Phyllanthus emblica Linn.on Candida adhesion to oral epithelium and denture acrylic

Objective:To investigate the effect of Phyllanthus emblica(P.emblica) Linn,ethanolic extract on the adhesion of Candida albicans(C.albicans) to human buccal epithelial cells(BECs) and denture acrylic surfaces.Methods:Human BECs and transparent acrylic strips were pretreated with ethanolic extract solution of P.emblica fruits at concentration ranged from 18.7 to 300 mg/mL.After washing BECs and the strips were inoculated with three strains of C.albicans (ATCC 10281 and two clinical isolates)(10~7 cells/mL).Normal saline solution(NSS) and 0.2% chlorhexidine gluconate were used as negative and positive controls,respectively.BECs were harvested on 12μm-polycarbonate filters(Millipore,USA).The membrane filters and the strips were stained with Gram stain.Adherent yeast cells on 100 randomly selected epithelial cells and 20 randomly selected fields on each strip were counted under microscope.The statistical significance was calculated by Kruskal-Wallis and Tukey tests at a significant level of P【0.05. Results:Significant lower numbers of all strains of yeasts adhering to BECs and acrylic strips were observed after exposure to 75-300 mg/mL of plant extract compared with NSS.Conclusions: The present study demonstrates that P.emblica ethanolic extract interferes with the adhesion of C. albicans to BECs and denture acrylic surfaces in vitro.

Residual feed intake in beef cattle and its association with carcass traits, ruminal solid-fraction bacteria, and epithelium gene expression

Background: Residual feed intake(RFI) describes an animal’s feed efficiency independent of growth performance.The objective of this study was to determine differences in growth performance, carcass traits, major bacteria attached to ruminal solids-fraction, and ruminal epithelium gene expression between the most-efficient and the least-efficient beef cattle. One-hundred and forty-nine Red Angus cattle were allocated to three contemporary groups according to sex and herd origin. Animals were fed a finishing diet in confinement for 70 d to determine the RFI category for each. Within each group, the two most-efficient(n = 6; RFI coefficient =-2.69 ± 0.58 kg dry matter intake(DMI)/d) and the two least-efficient animals(n = 6; RFI coefficient = 3.08 ± 0.55 kg DMI/d) were selected. Immediately after slaughter, ruminal solids-fraction and ruminal epithelium were collected for bacteria relative abundance and epithelial gene expression analyses, respectively, using real-time PCR.Results: The most-efficient animals consumed less feed(P = 0.01; 5.03 kg less DMI/d) compared with the leastefficient animals. No differences(P > 0.10) in initial body weight(BW), final BW, and average daily gain(ADG) were observed between the two RFI classes. There were no significant RFI × sex effects(P > 0.10) on growth performance.Compared with the least-efficient group, hot carcass weight(HCW), ribeye area(REA), and kidney, pelvic, and heart fat(KPH) were greater(P ≤ 0.05) in the most-efficient cattle. No RFI × sex effect(P > 0.10) for carcass traits was detected between RFI groups. Of the 10 bacterial species evaluated, the most-efficient compared with least efficient cattle had greater(P ≤ 0.05) relative abundance of Eubacterium ruminantium, Fibrobacter succinogenes, and Megasphaera elsdenii, and lower(P ≤ 0.05) Succinimonas amylolytica and total bacterial density. No RFI × sex effect on ruminal bacteria was detected between RFI groups. Of the 34 genes evaluated in ruminal epithelium, the mostefficient cattle had greater(P ≤ 0.05) abundance of genes involved in VFA absorption, metabolism, ketogenesis, and immune/inflammation-response. The RFI × sex interactions indicated that responses in gene expression between RFI groups were due to differences in sex. Steers in the most-efficient compared with least-efficient group had greater(P ≤ 0.05) expression of SLC9 A1, HIF1 A, and ACO2. The most-efficient compared with least-efficient heifers had greater(P ≤ 0.05) m RNA expression of BDH1 and lower expression(P ≤ 0.05) of SLC9 A2 and PDHA1.Conclusions: The present study revealed that greater feed efficiency in beef cattle is associated with differences in bacterial species and transcriptional adaptations in the ruminal epithelium that might enhance nutrient delivery and utilization by tissues. The lack of RFI × sex interaction for growth performance and carcass traits indicates that sex may not play a major role in improving these phenotypes in superior RFI beef cattle. However, it is important to note that this result should not be considered a solid biomarker of efficient beef cattle prior to further examination due to the limited number of heifers compared with steers used in the study.