Chicken Red Blood Cells Research Articles

Role of Sequence and Structure of the Hendra Fusion Protein Fusion Peptide in Membrane Fusion

Viral fusion proteins are intriguing molecular machines that undergo drastic conformational changes to facilitate virus-cell membrane fusion. During fusion a hydrophobic region of the protein, termed the fusion peptide (FP), is inserted into the target host cell membrane, with subsequent conformational changes culminating in membrane merger. Class I fusion proteins contain FPs between 20 and 30 amino acids in length that are highly conserved within viral families but not between. To examine the sequence dependence of the Hendra virus (HeV) fusion (F) protein FP, the first eight amino acids were mutated first as double, then single, alanine mutants. Mutation of highly conserved glycine residues resulted in inefficient F protein expression and processing, whereas substitution of valine residues resulted in hypofusogenic F proteins despite wild-type surface expression levels. Synthetic peptides corresponding to a portion of the HeV F FP were shown to adopt an α-helical secondary structure in dodecylphosphocholine micelles and small unilamellar vesicles using circular dichroism spectroscopy. Interestingly, peptides containing point mutations that promote lower levels of cell-cell fusion within the context of the whole F protein were less α-helical and induced less membrane disorder in model membranes. These data represent the first extensive structure-function relationship of any paramyxovirus FP and demonstrate that the HeV F FP and potentially other paramyxovirus FPs likely require an α-helical structure for efficient membrane disordering and fusion.

Nonlinear electro-mechanobiological behavior of cell membrane during electroporation

A nonlinear electroporation (EP) model is proposed to study the electro-mechanobiological behavior of cell membrane during EP, by taking the nonlinear large deformation of the membrane into account. The proposed model predicts the critical transmembrane potential and the activation energy for EP, the equilibrium pore size, and the resealing process of the pore. Single-cell EP experiments using a micro EP chip were conducted on chicken red blood cells at different temperatures to determine the activation energy and the critical transmembrane potential for EP. The experimental results are in good agreement with the theoretical predictions.

Comparison of serological assays for detecting antibodies in ducks exposed to H5 subtype avian influenza virus

BackgroundChicken red blood cells (RBCs) are commonly used in hemagglutination inhibition (HI) tests to measure hemagglutinating antibodies against influenza viruses. The use of horse RBCs in the HI test can reportedly increase its sensitivity when testing human sera for avian influenza antibodies. This study aims to compare the proportion of positives detected and the agreement between two HI tests using either chicken or horse red blood cells for antibody detection in sera of ducks experimentally infected or naturally exposed to Indonesian H5 subtype avian influenza virus. In addition, comparison with a virus neutralisation (VN) test was conducted with the experimental sera.ResultsIn the experimental study, the proportion of HI antibody-positive ducks increased slightly, from 0.57 when using chicken RBCs to 0.60 when using horse RBCs. The HI tests indicated almost perfect agreement (kappa = 0.86) when results were dichotomised (titre ≥ 4 log2), and substantial agreement (weighted kappa = 0.80) for log titres. Overall agreements between the two HI tests were greater than between either of the HI tests and the VN test. The use of horse RBCs also identified a higher proportion of antibody positives in field duck sera (0.08, compared to chicken RBCs 0.02), with also almost perfect agreements for dichotomized results (Prevalence and bias adjusted Kappa (PABAK) = 0.88) and for log titres (weighted PABAK = 0.93), respectively. Factors that might explain observed differences in the proportion of antibody-positive ducks and in the agreements between HI tests are discussed.ConclusionIn conclusion, we identified a good agreement between HI tests. However, when horse RBCs were used, a higher proportion of sera was positive (titre ≥ 4 log2) than using chicken RBCs, especially during the early response against H5N1 virus. The HRBC-HI might be more responsive in identifying early H5N1 HPAI serological response and could be a recommended assay for avian influenza sero-surveillance in both wild and domestic birds.

Rapid detection of avian influenza H5N1 virus using impedance measurement of immuno-reaction coupled with RBC amplification

Avian influenza virus (AIV) subtype H5N1 was first discovered in the 1990s and since then its emergence has become a likely source of a global pandemic and economic loss. Currently accepted gold standard methods of influenza detection, viral culture and rRT-PCR, are time consuming, expensive and require special training and laboratory facilities. A rapid, sensitive, and specific screening method is needed for in-field or bedside testing of AI virus to effectively implement quarantines and medications. Therefore, the objective of this study was to improve the specificity and sensitivity of an impedance biosensor that has been developed for the screening of AIV H5. Three major components of the developed biosensor are immunomagnetic nanoparticles for the separation of AI virus, a microfluidic chip for sample control and an interdigitated microelectrode for impedance measurement. In this study polyclonal antibody against N1 subtype was immobilized on the surface of the microelectrode to specifically bind AIV H5N1 to generate more specific impedance signal and chicken red blood cells (RBC) were used as biolabels to attach to AIV H5N1 captured on the microelectrode to amplify impedance signal. RBC amplification was shown to increase the impedance signal change by more than 100% compared to the protocol without RBC biolabels, and was necessary for forming a linear calibration curve for the biosensor. The use of a second antibody against N1 offered much greater specificity and reliability than the previous biosensor protocol. The biosensor was able to detect AIV H5N1 at concentrations down to 103 EID50ml−1 in less than 2h.

Diagnostic performance of the canine Influenza A Virus subtype H3N8 hemagglutination inhibition assay

Canine Influenza A virus subtype H3N8 (H3N8 CIV) was recognized in 2004 as a novel respiratory pathogen for dogs. To date, infections have been diagnosed in thousands of dogs in 38 U.S. states. Diagnostic techniques such as reverse transcription polymerase chain reaction (RT-PCR) and virus isolation may yield false-negative results if samples are collected after virus shedding has ceased. Therefore, serology is often necessary to confirm diagnosis. The hemagglutination inhibition (HI) assay is the test of choice for serological diagnosis of influenza infections in animals. However, discrepancies exist between diagnostic laboratories and research groups in some of the test parameters for the H3N8 CIV HI assay and the cutoff antibody titer for seropositivity. The objectives of the current study were 1) to assess the diagnostic performance of a H3N8 CIV HI assay using field sera from canine infectious respiratory disease outbreaks and 2) to evaluate the effect of test parameter variations on test performance, including the use of different red blood cell (RBC) species, serum treatment methods, and virus isolates. Based on a receiver operating characteristic analysis using serum microneutralization assay titers as the gold standard, the H3N8 CIV HI assay described in the present study is highly sensitive (99.6%) and specific (94.6%) when the cutoff antibody titer for seropositivity is 32. Evaluation of parameter variations determined that the sensitivity and specificity of the H3N8 CIV HI assay depend on serum pretreatment with a receptor-destroying enzyme or periodate, use of 0.5% turkey or chicken RBCs, and use of antigenically well-matched H3N8 virus strains.

Identification of Dual Receptor-binding Specific Strains of Human H5N1 Viruses in China

ObjectiveBoth the 2, 6 linkage and its topology on target cells are critical for the recognition by human influenza virus. The binding preference of avian flu virus H5N1 HA to the 2, 3-linked sialylated glycans is considered the major factor limiting its efficient infection and transmission in humans. To monitor potential adaptation of H5N1 virus in human population, the surveillance of receptor-binding specificity was undertaken in China. MethodsThe binding specificity of 32 human H5N1 virus strains isolated from 2003 to 2009 was tested by 2, 3-specific sialidase-treated chicken red blood cell (CRBC) agglutination assay and a solid-phase direct binding assay with synthetic sialylglycopolymers. ResultsDual binding preference to 2, 3 and 2, 6-glycans were found in two strains: A/Guangdong/1/06 (A/GD/1/06) and A/Guangxi/1/08 (A/GX/1/08). Though minor effect of short-2, 6-binding was detected in A/GX/1/08 at a low virus titer, both showed high affinity to the oligosaccharide at a high load. Notably both are of the long-2, 6-recognition, with the same topology as that of human H1N1 and H3N2 viruses. ConclusionThe findings suggest that human H5N1 virus in China likely acquired the potential human-adaptation ability. Further research and surveillance on receptor-binding specificity of H5N1 viruses are required.

Evaluation of cellular immune response in Golden Hamsters experimentally infected with Leishmania donovani comparing with cellular immune response against chicken Red Blood Cells.

The Evaluation of the immune response in Golden Hamsters experimentally infected with Leishmania donovani was determined in this study, particularly, the cellular immune response. Follow up has maintained to determine the Delayed Type of Hypersensitivity using skin test both in infected and control lab animals. Chicken red blood cells were used as a parameter to evaluate the immune system; they are dull and have the ability of immunization. Two concentrations of chicken R.B.C were examined to determine which gives the higher titration in Hamsters and those were 1.5 X 109 cell/ml and 3 X 109 cell/ml , the second concentration gave the maximum titration where then used in this work. After sensitization with Chicken R.B.C for both infected and control groups, delayed type of hypersensitivity has been used against Leishmania donovani antigen and 4 days of follow up were adopted and they were (14, 30, 60, 90) day after infection. Results showed that skin test against both antigens ( L.donovani and chicken R.B.C) was significantly higher than normal at the first day of follow up ( day 14) then gradual decreasing were noticed till the last day of follow up (90). This can indicate that the infection with L.donovani activated the immune response at the beginning of infection, then leads to cellular immune suppression against both L.donovani antigen and chicken R.B.C., so that this immunosuppression is not specific.

Evaluation of cellular immune response in Golden Hamsters experimentally infected with Leishmania donovani comparing with cellular immune response against chicken Red Blood Cells.

The Evaluation of the immune response in Golden Hamsters experimentally infected with Leishmania donovani was determined in this study, particularly, the cellular immune response. Follow up has maintained to determine the Delayed Type of Hypersensitivity using skin test both in infected and control lab animals. Chicken red blood cells were used as a parameter to evaluate the immune system; they are dull and have the ability of immunization. Two concentrations of chicken R.B.C were examined to determine which gives the higher titration in Hamsters and those were 1.5 X 109 cell/ml and 3 X 109 cell/ml , the second concentration gave the maximum titration where then used in this work. After sensitization with Chicken R.B.C for both infected and control groups, delayed type of hypersensitivity has been used against Leishmania donovani antigen and 4 days of follow up were adopted and they were (14, 30, 60, 90) day after infection. Results showed that skin test against both antigens ( L.donovani and chicken R.B.C) was significantly higher than normal at the first day of follow up ( day 14) then gradual decreasing were noticed till the last day of follow up (90). This can indicate that the infection with L.donovani activated the immune response at the beginning of infection, then leads to cellular immune suppression against both L.donovani antigen and chicken R.B.C., so that this immunosuppression is not specific.

Environment: a potential source of animal and human infection with influenza A (H5N1) virus

Very little is known regarding the persistence of highly pathogenic avian influenza H5N1 viruses in natural settings during outbreaks in tropical countries, although environmental factors may well play a role in the persistence and in the transmission of H5N1 virus. To investigate various environmental compartments surrounding outbreak areas as potential sources for H5N1 virus transmission. Environmental specimens were collected following outbreaks of avian influenza in Cambodia between April 2007 and February 2010. The methods used to concentrate H5N1 virus from water samples were based either on agglutination of the virus with chicken red blood cells or on adsorption on glass wool, followed by an elution-concentration step. An elution-concentration method was used for mud specimens. All samples that tested positive by real-time RT-PCRs (qRT-PCRs) targeting the HA5, M and NA1 genes were inoculated into embryonated hen eggs for virus isolation. Of a total of 246 samples, 46 (19%) tested positive for H5N1 by qRT-PCRs. Viral RNA was frequently detected in dust, mud and soil samples from the farms' environment (respectively, 46%, 31% and 15%). Samples collected from ponds gave a lower proportion of positive samples (6%) as compared to those collected from the farms (24%). In only one sample, infectious virus particles were successfully isolated. During H5N1 virus outbreaks, numerous environmental samples surrounding outbreak areas are contaminated by the virus and may act as potential sources for human and/or animal contamination.

Effect of Dietary Supplementation of Achyranthes aspera Seed on the Immune System of Labeo rohita Fry

Labeo rohita (rohu) fry (0.547±0.01 g) were fed one of four diets containing 0 (control), 0.1, 0.5, or 1.0% Achyranthes aspera seed. After 30 days, the fry were immunized with chicken red blood cells (c-RBC). Blood samples were collected 7, 14, and 21 days after immunization. Significantly (p<0.05) higher average weight (2.565±0.02 g) and SGR were were obtained in fry fed the 1.0% diet compared to others. The increase in average weight was directly related to the increasing dose of seed. FCR was significantly (p<0.05) lower in fry fed the 1.0% diet while total serum protein, albumin, and globulin were higher in treated groups than in the unsupplemented control. The antigen-specific antibody titer level was significantly (p<0.05) lower in rohu fed the control diet than in rohu fed the supplemented diets. Titer levels were 32-128, 128-256, 256-1024, and 256-1024 in the 0, 0.1, 0.5, and 1.0% diets, respectively. Serum glutamic oxaloacetic transaminase (SGOT), serum glutamate pyruvate transaminase (SGPT), and alkaline phosphatase (ALP) were significantly (p<0.05) higher in rohu fed the control diet than in rohu fed the supplemented diets while myeloperoxidas was lower in the former. Among the treated groups, myeloperoxidase was significantly (p<0.05) higher in rohu fed the 1.0% diet (1.561-2.558, ? 450 nm) than in those fed other diets. The present study documents the immunostimulatory properties of A. aspera seed and finds that a dose of 1.0% might be suitable for rohu fry.

Inhibition of Influenza A Virus (H1N1) Fusion by Benzenesulfonamide Derivatives Targeting Viral Hemagglutinin

Hemagglutinin (HA) of the influenza virus plays a crucial role in the early stage of the viral life cycle by binding to sialic acid on the surface of host epithelial cells and mediating fusion between virus envelope and endosome membrane for the release of viral genomes into the cytoplasm. To initiate virus fusion, endosome pH is lowered by acidification causing an irreversible conformational change of HA, which in turn results in a fusogenic HA. In this study, we describe characterization of an HA inhibitor of influenza H1N1 viruses, RO5464466. One-cycle time course study in MDCK cells showed that this compound acted at an early step of influenza virus replication. Results from HA-mediated hemolysis of chicken red blood cells and trypsin sensitivity assay of isolated HA clearly showed that RO5464466 targeted HA. In cell-based assays involving multiple rounds of virus infection and replication, RO5464466 inhibited an established influenza infection. The overall production of progeny viruses, as a result of the compound's inhibitory effect on fusion, was dramatically reduced by 8 log units when compared with a negative control. Furthermore, RO5487624, a close analogue of RO5464466, with pharmacokinetic properties suitable for in vivo efficacy studies displayed a protective effect on mice that were lethally challenged with influenza H1N1 virus. These results might benefit further characterization and development of novel anti-influenza agents by targeting viral hemagglutinin.

Immunomodulatory Activity of Polysaccharide-Protein Complex of Longan (Dimocarpus longan Lour.) Pulp

The immunomodulatory function of longan pulp polysaccharide-protein complex (LP3) was investigated in immunosuppressed mice models. Compared with the model control, peroral administration of 100 mgkg−1d−1 LP3 could significantly increase/enhance antibody production against chicken red blood cell (CRBC), concanavalin A (ConA)-induced splenocyte proliferation, macrophage phagocytosis, NK cell cytotoxicity against YAC-1 lymphoma cell, and interferon-gamma (INF-γ) and interleukin-2 (IL-2) secretion in serum (P < 0.05). The immunomodulatory effects, except for those on splenocytes and macrophages (P > 0.05), were also observed in mice administered with 50 or 200 mgkg−1d−1 LP3 (P < 0.05). The beneficial effects of 50–200 mgkg−1d−1 LP3 were comparable to those of 50 mgkg−1d−1 ganoderan. The strong immunomodulatory activity of LP3 confirmed its good potential as an immunotherapeutic adjuvant.

Antiviral activity of arbidol, a broad‐spectrum drug for use against respiratory viruses, varies according to test conditions

The therapeutic activity of arbidol was investigated against representatives of seven different virus families. Its 50% median effective concentration (EC(50) ) was 0.22-11.8 µg/ml (0.41-22 nM). Therapeutic indices of 91 were obtained for type 1 poliovirus and 1.9-8.5 for influenza A and B, human paramyxo-3, avian infectious bronchitis-, and Marek's disease viruses. Arbidol was more inhibitory for influenza A/Aichi/2/68 (H3N2) virus than rimantadine or amantadine (EC(50) 10 vs. >15 and >31.6 µg/ml); greater inhibition occurred when end-points were expressed as TCID(50) s. For respiratory syncytial virus (RSV), a reduction in plaque size but not number was observed. However, when the drug was added to infected cultures (≥5 µg/ml), a 3-log reduction in titer occurred. Arbidol did not inhibit directly influenza A/Aichi/2/68 hemagglutinin (HA) or neuraminidase (NA) activity, but inhibition of fusion between the viral envelope and chicken red blood cells occurred when added at 0.1 µg/ml prior to infection. Arbidol induced changes to viral mRNA synthesis of the PB2, PA, NP, NA, and NS genes in MDCK cultures infected with influenza A/PR/8/34. There was no indirect evidence of enhancement of interferon-α by arbidol following infection with A/Aichi/2/68. Arbidol neither reduced lung viral titers nor caused a significant reduction of lung consolidation in BALB/c mice after administration by the oral and intraperitoneal (i.p.) routes and intranasal challenge with influenza A/Aichi/2/68. A small reduction in lung consolidation, but not viral titer, occurred after i.p. administration and subsequent challenge with RSV. The results indicate the potential of arbidol as a broad-spectrum respiratory antiviral drug.

Immunomodulatory effects of decaffeinated green tea ( Camellia sinensis) on the immune system of rainbow trout ( Oncorhynchus mykiss)

In order to study the immunomodulatory effects of decaffeinated green tea extract on rainbow trout, a study with a 30-day feeding trial was conducted. Commercial diets with graded levels of decaffeinated green tea extract, 20 mg (T1), 100 mg (T2), 500 mg (T3) per kg feed were prepared. 120 rainbow trout (35 ± 3 g) were randomly assigned to 4 groups in triplicates and fed one of the 3 experimental diets formulated or control diet. After feeding trial, 12 fish from each group were sampled for analysis of some immunological parameters. Remaining fish were injected with 0.5 ml of chicken red blood cell (C-RBC) suspension (2%) intraperitoneally on days 5 and 15 after feeding trial. Results of the current study showed that the inclusion of 20 mg kg-1 green tea (T1) in fish diet enhanced the serum bactericidal activity against Yersinia ruckeri, while significant elevation of lysozyme activity was shown in T2 group. Anti-trypsin activity due to α1-antiprotease was significantly higher in T1 and T2 groups while peroxidase content showed significant increase in all treatment groups compared to control group. Hemagglutination antibody titer against C-RBC was significantly higher in fish administered with 100 mg kg −1 green tea (T2). Our findings showed that decaffeinated green tea in lower doses of administration could be optimum to enhance the immunity of rainbow trout.

Extent of Antigenic Cross-Reactivity among Highly Pathogenic H5N1 Influenza Viruses

Highly pathogenic H5N1 avian influenza viruses emerged in 1996 and have since evolved so extensively that a single strain can no longer be used as a prepandemic vaccine or diagnostic reagent. We therefore sought to identify the H5N1 strains that may best serve as cross-reactive diagnostic reagents. We compared the cross-reactivity of 27 viruses of clades 0, 1, 2.1, 2.2, 2.3, and 4 and of four computationally designed ancestral H5N1 strains by hemagglutination inhibition (HI) and microneutralization (MN) assays. Antigenic cartography was used to analyze the large quantity of resulting data. Cartographs of HI titers with chicken red blood cells were similar to those of MN titers, but HI with horse red blood cells decreased antigenic distances among the H5N1 strains studied. Thus, HI with horse red blood cells seems to be the assay of choice for H5N1 diagnostics. Whereas clade 2.2 antigens were able to detect antibodies raised to most of the tested H5N1 viruses (and clade 2.2-specific antisera detected most of the H5N1 antigens), ancestral strain A exhibited the widest reactivity pattern and hence was the best candidate diagnostic reagent for broad detection of H5N1 strains.

Preliminary comparison of different immune and production components in local and imported Saanen goats reared under a sub-tropical environment

Three objectives were included in this research work. The first objective compared different immune components in healthy mature males, mature females, and female kids of local and imported Saanen goats, reared under a sub-tropical environment. The significantly differing immune components were the blood monocyte percent, blood CD8 count, and the total white blood cell count. The second objective compared the performance of Saanen versus local does. The means of the milk yield and prolificacy of the imported Saanen does were significantly higher than those of the local does (p<0.05). The third objective compared the immune responses (hemagglutination-HA titers) and complement fixation (CF) titers in mature does of the two breeds to chicken red blood cells (c-RBC). The HA titers showed a significant seroconversion only in imported Saanen (p<0.05) but not in local does; however, the CF titers increased significantly at 4 weeks following priming with c-RBC in local (p<0.05) but not in the imported Saanen does. The impact of the differences in blood immune components and responses to antigens in the compared goats on protection potential against prevalent diseases in the sub-tropical zone of the eastern Mediterranean countries is discussed.

In Vitro and In Vivo Antitumor Activity of Scutellaria barbate Extract on Murine Liver Cancer

In the present study, we investigated the in vitro and in vivo antitumor effects of crude extract of Scutellaria barbate (CE-SB) on mouse hepatoma H22 cells. The MTT assay was used to determine the growth inhibition of H22 cells in vitro. The in vivo therapeutic effects of CE-SB were determined using H22 tumor bearing mice. Besides, the body weight, tumor weight, thymus index and spleen index of H22 bearing mice were also measured. The tumor inhibitory rate (IR) was calculated according to the mean weight of tumor (MWT). The phagocytotic function of macrophages was examined by observing peritoneal macrophages phagocytize chicken RBC. The results showed that CE-SB could inhibit the growth of hepatoma H22 Cells in vitro and in vivo. Furthermore, CE-SB could improve immune function of H22 tumor bearing mice. Together these results indicate that CE-SB has antitumor activity and seems to be safe and effective for the use of anti-tumor therapy.

Glycomics‐based analysis of chicken red blood cells provides insight into the selectivity of the viral agglutination assay

Agglutination of red blood cells (RBCs), including chicken RBCs (cRBCs), has been used extensively to estimate viral titer, to screen glycan-receptor binding preference, and to assess the protective response of vaccines. Although this assay enjoys widespread use, some virus strains do not agglutinate RBCs. To address these underlying issues and to increase the usefulness of cRBCs as tools for studying viruses, such as influenza, we analyzed the cell surface N-glycans of cRBCs. On the basis of the results obtained from complementary analytical strategies, including MS, 1D and 2D-NMR spectroscopy, exoglycosidase digestions, and HPLC profiling, we report the major glycan structures present on cRBCs. By comparing the glycan structures of cBRCs with those of representative human upper respiratory cells, we offer a possible explanation for the fact that certain influenza strains do not agglutinate cRBCs, using specific human-adapted influenza hemagglutinins as examples. Finally, recent understanding of the role of various glycan structures in high affinity binding to influenza hemagglutinins provides context to our findings. These results illustrate that the field of glycomics can provide important information with respect to the experimental systems used to characterize, detect and study viruses.

Antiviral activity and possible mechanisms of action of pentagalloylglucose (PGG) against influenza A virus

Influenza A virus (IAV) infection is a major public health threat leading to significant morbidity and mortality. The emergence of drug-resistant virus strains highlights the urgent need to develop novel antiviral drugs with alternative modes of action. Pentagalloylglucose (PGG), a naturally occurring polyphenolic compound, possesses a broad spectrum of biological activities. In this study, we found that PGG has anti-influenza-virus activity, and investigated its possible mechanism(s) of action in vitro. Both pre-incubation of virus prior to infection and post-exposure of infected cells with PGG significantly inhibited virus yields. Influenza-virus-induced hemagglutination of chicken red blood cells was inhibited by PGG treatment, suggesting that PGG can inhibit IAV infection by interacting with the viral hemagglutinin. PGG did not affect viral protein synthesis or nuclear transport of viral nucleoprotein (NP) but greatly reduced plasma membrane accumulation of NP protein at the late stage of the replication cycle. Furthermore, PGG significantly reduced virus budding and progeny virus release from infected cells. This study revealed for the first time that PGG can inhibit IAV replication with a dual mode of action and offers new insights into its underlying mechanisms of antiviral action.

Replacement of groundnut cake with sunflower and karanj seed cakes on performance, nutrient utilisation, immune response and carcass characteristics in Nellore lambs

An experiment was conducted with 21 Nellore male lambs (9–10 months age) of uniform body weight (27.6 ± 1.03 kg) to assess the effect of replacing groundnut cake (GNC) totally with sunflower seed cake (SFC) and karanj seed cake (KSC) in sorghum stover-based complete diets on growth performance, nutrient utilisation, immune response and carcass traits. Lambs were randomly assigned to a control diet (13.0% GNC) and two test diets containing SFC (14.5%) and KSC (12.0%), as sole protein supplements and fed respective diets according to requirements recommended by the Indian Council of Agricultural Research, 1998 for a period of 155 days. Daily feed intake and fortnightly body weight of each lamb were recorded throughout the feeding trial. After 120 days, a metabolic trial of 6 days was conducted to determine nutrient digestibilities and balances. After the 75th day, all lambs were sensitised intramuscularly with heat-killed Brucella abortus S 99 and 20% chicken red blood cell (RBC) suspension and a booster was given after 15 days to assess the humoral immune response. Antibody titres were estimated in serum collected from sensitised lambs on 7, 14, 21, 28 and 35th day post sensitisation. The cell-mediated immune response was assessed by delayed type hypersensitive (DTH) reaction against phytohemagglutinin-P and in vitro lymphocyte proliferative assay (LPA) on the 150th day of the experiment. On the 155th day, four representative lambs from each group were slaughtered for carcass studies. The karanjin content in KSC estimated by high-performance liquid chromatography (HPLC) was 0.325%, hence constituted 390 mg karanjin per kg diet. Dry matter (DM), nutrient intake and digestibilities of proximate constituents, energy and fibre fractions by SFC- and GNC-fed lambs did not differ, but DM and nutrient intake by lambs which were fed KSC was lowered ( P < 0.05) compared to other diets. This resulted in lower ( P < 0.05) growth rates, nutrient efficiency and relatively higher digestibility co-efficients for DM, organic matter, crude fat, nitrogen-free extract, energy and neutral detergent fibre in KSC-fed lambs. Balance of phosphorus (P) was comparable among the groups, but calcium (Ca) and nitrogen (N) balance was lower ( P < 0.05) in KSC-fed lambs. Antibody titres against B. abortus and chicken RBC was depressed ( P < 0.05) in lambs which were fed KSC diet on the 7th day post sensitisation, while such depression was not observed with SFC feeding. The DTH response and in vitro LPA response were not affected by SFC, but the response was lower on KSC diet. No effect of variation in protein supplements was observed on carcass characteristics. The study indicated that the incorporation of SFC as the sole protein source in the diets of lambs had no effect on body weight, nutrient intake, nutrient digestibilities, immune response and carcass traits. But with 12% KSC inclusion in complete diets (390 mg karanjin per kg), there was depressed performance and immunocompetence in lambs.