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BackgroundApproximately 50% of patients who receive anti-CD19 CAR-T cells relapse, and new immunotherapeutic targets are urgently needed. We recently described CD72 as a promising target in B-cell malignancies and developed nanobody-based CAR-T cells (nanoCARs) against it. This cellular therapy design is understudied compared with scFv-based CAR-T cells, but has recently become of significant interest given the first regulatory approval of a nanoCAR in multiple myeloma.MethodsWe humanized our previous nanobody framework regions, derived from llama, to generate a series of humanized anti-CD72 nanobodies. These nanobody binders were inserted into second-generation CD72 CAR-T cells and were evaluated against preclinical models of B cell acute lymphoblastic leukemia and B cell non-Hodgkin's lymphoma in vitro and in vivo. Humanized CD72 nanoCARs were compared with parental ("NbD4") CD72 nanoCARs and the clinically approved CD19-directed CAR-T construct tisangenlecleucel. RNA-sequencing, flow cytometry, and cytokine secretion profiling were used to determine differences between the different CAR constructs. We then used affinity maturation on the parental NbD4 construct to generate high affinity binders against CD72 to test if higher affinity to CD72 improved antitumor potency.ResultsToward clinical translation, here we humanize our previous nanobody framework regions, derived from llama, and surprisingly discover a clone ("H24") with enhanced potency against B-cell tumors, including patient-derived samples after CD19 CAR-T relapse. Potentially underpinning improved potency, H24 has moderately higher binding affinity to CD72 compared with a fully llama framework. However, further affinity maturation (KD

Rhodopsin is a prototypical G protein-coupled receptor (GPCR) critical for vertebrate vision. Research on GPCR signaling states has been facilitated using llama-derived nanobodies (Nbs), some of which bind to the intracellular surface to allosterically modulate the receptor. Extracellularly binding allosteric nanobodies have also been investigated, but the structural basis for their activity has not been resolved to date. Here, we report a library of Nbs that bind to the extracellular surface of rhodopsin and allosterically modulate the thermodynamics of its activation process. Crystal structures of Nb2 in complex with native rhodopsin reveal a mechanism of allosteric modulation involving extracellular loop 2 and native glycans. Nb2 binding suppresses Schiff base deprotonation and hydrolysis and prevents intracellular outward movement of helices five and six - a universal activation event for GPCRs. Nb2 also mitigates protein misfolding in a disease-associated mutant rhodopsin. Our data show the power of nanobodies to modulate the photoactivation of rhodopsin and potentially serve as therapeutic agents for disease-associated rhodopsin misfolding.

A two-week-old female llama cria was brought to the UC Davis Large Animal Hospital for evaluation of a cardiac murmur and suspected syncopal episodes. A grade IV/VI left basilar continuous murmur was present on cardiac auscultation. Echocardiography revealed a left-to-right shunting patent ductus arteriosus (PDA), mild left ventricular enlargement, scant pericardial effusion, and a suspected persistent left cranial vena cava. The PDA was successfully closed with an Amplatz canine duct occluder. Mild mitral regurgitation was present on echocardiography performed 7 d following PDA occlusion. No syncopal episodes were observed in hospital prior to or following PDA occlusion. At approximately 1 mo following PDA closure, a grade I/VI left apical systolic murmur was present and the cria's body condition was improved. Key clinical message: Patent ductus arteriosus closure is achievable in New World camelids using interventional cardiology which provides a minimally invasive treatment option for valuable or companion animals. Since interventional cardiac catheterization is commonly performed in small animal species, veterinary cardiologists are well-equipped to apply these skills to camelids.

Several plants that contain indolizidine alkaloids, including swainsonine, are toxic to livestock, causing dysfunctional lysosomes and storage disease. Swainsonine induces a neurovisceral disease, known as locoism, in sheep, goats, and cattle, which occurs in several parts of the world, including, but not limited to, the western United States, China, and parts of Australia. In South America, locoism has been described in the Andean region of Argentina affecting sheep, cattle, and llamas. Intoxication by consumption of Astragalus punae was suspected in 4 llamas in Jujuy Province, northwestern Argentina. The grazing area contained abundant specimens of A. punae. The clinical course was ~15 d, and included moderate ataxia, incoordination of hindlimbs, and progressive loss of body condition. Microscopically, fine cytoplasmic microvacuolation was observed in the proximal convoluted renal tubules. Ultrastructurally, these changes consisted of severely dilated lysosomes. Swainsonine was detected in stem and leaf samples of A. punae at a concentration of 0.06%. Based on clinical history and signs, histologic and ultrastructural changes, and plant analysis, a diagnosis of swainsonine toxicosis caused by consumption of A. punae was made, which has not been reported previously, to our knowledge.

The Lake Titicaca basin was one of the major centers for cultural development in the ancient world. This lacustrine environment is unique in the high, dry Andean altiplano, and its aquatic and terrestrial resources are thought to have contributed to the florescence of complex societies in this region. Nevertheless, it remains unclear to what extent local aquatic resources, particularly fish, and the introduced crop, maize, which can be grown in regions along the lakeshores, contributed to facilitating sustained food production and population growth, which underpinned increasing social political complexity starting in the Formative Period (1400 BCE to 500 CE) and culminating with the Tiwanaku state (500 to 1100 CE). Here, we present direct dietary evidence from stable isotope analysis of human skeletal remains spanning over two millennia, together with faunal and floral reference materials, to reconstruct foodways and ecological interactions in southern Lake Titicaca over time. Bulk stable isotope analysis, coupled with compound-specific amino acid stable isotope analysis, allows better discrimination between resources consumed across aquatic and terrestrial environments. Together, this evidence demonstrates that human diets predominantly relied on C3 plants, particularly quinoa and tubers, along with terrestrial animals, notably domestic camelids. Surprisingly, fish were not a significant source of animal protein, but a slight increase in C4 plant consumption verifies the increasing importance of maize in the Middle Horizon. These results underscore the primary role of local terrestrial food resources in securing a nutritious diet that allowed for sustained population growth, even in the face of documented climate and political change across these periods.

Nanobodies (nAbs) are recombinant antigen-binding variable domain fragments obtained from heavy-chain-only immunoglobulins. Among mammals, these are unique to camelids (camels, llamas, alpacas, etc.). Nanobodies are of great use in biomedical research due to their efficient folding and stability under a variety of conditions, as well as their small size. The latter characteristic is particularly important for nAbs used as immunolabeling reagents, since this can improve penetration of cell and tissue samples compared to conventional antibodies, and also reduce the gap distance between signal and target, thereby improving imaging resolution. In addition, their recombinant nature allows for unambiguous definition and permanent archiving in the form of DNA sequence, enhanced distribution in the form of sequences or plasmids, and easy and inexpensive production using well-established bacterial expression systems, such as the IPTG induction method described here. This article will review the basic workflow and process for developing, screening, and validating novel nAbs against neuronal target proteins. The protocols described make use of the most common nAb development method, wherein an immune repertoire from an immunized llama is screened via phage display technology. Selected nAbs can then be taken through validation assays for use as immunolabels or as intrabodies in neurons. © 2020 Wiley Periodicals LLC. Basic Protocol 1: Total RNA isolation from camelid leukocytes Basic Protocol 2: First-strand cDNA synthesis; VH H and VH repertoire PCR Basic Protocol 3: Preparation of the phage display library Basic Protocol 4: Panning of the phage display library Basic Protocol 5: Small-scale nAb expression Basic Protocol 6: Sequence analysis of selected nAb clones Basic Protocol 7: Nanobody validation as immunolabels Basic Protocol 8: Generation of nAb-pEGFP mammalian expression constructs Basic Protocol 9: Nanobody validation as intrabodies Support Protocol 1: ELISA for llama serum testing, phage titer, and screening of selected clones Support Protocol 2: Amplification of helper phage stock Support Protocol 3: nAb expression in amber suppressor E. coli bacterial strains.

Lysosomal storage diseases are inherited and acquired disorders characterized by dysfunctional lysosomes. Intracytoplasmic accumulation of undegraded substrates leads to impaired cellular function and death. Several plant species are toxic to livestock because of the presence of indolizidine alkaloids, including swainsonine, which cause a storage disease. Swainsonine-induced nervous disease (i.e., locoism) of sheep and cattle is well recognized in several parts of the world, particularly in the western United States and in parts of Australia. Spontaneous intoxication by Astragalus garbancillo var. garbancillo was suspected in a group of 70 llamas (Lama glama) in Jujuy Province, northwestern Argentina. The animals grazed an area dominated by stands of A. garbancillo var. garbancillo. Clinical signs were staggering, ataxia, hypermetria, and progressive weight loss. The clinical course in individual animals was ~50 d. The main microscopic changes were Purkinje cell degeneration, necrosis, and loss, associated with intracytoplasmic vacuolation, meganeurite formation, and Wallerian degeneration. Specific positive labeling for ubiquitin was observed in axonal spheroids. Composite leaf and stem samples of A. garbancillo var. garbancillo analyzed by high-performance liquid chromatography contained 0.03% swainsonine. Based on the microscopic lesions, clinical history, and plant analysis, a diagnosis was made of storage disease caused by consumption of swainsonine-containing A. garbancillo var. garbancillo.

Ulcers of the oral cavity, esophagus, and gastric compartments of South American camelids are uncommon. Multifocal-to-coalescing ulcers were identified in the oral cavity, esophagus, and/or gastric compartments of 5 alpacas submitted for postmortem examination. Fusobacterium necrophorum was isolated from the lesions in all alpacas, in combination with other aerobic and anaerobic bacteria. In 4 of these cases, F. necrophorum-associated lesions were considered secondary to neoplasia or other chronic debilitating conditions; in 1 case, the alimentary ulcers were considered the most significant autopsy finding. It is not known if this agent acted as a primary or opportunistic agent in mucosal membranes previously damaged by a traumatic event, chemical insult, immunodeficiency, or any other debilitating condition of the host.

Tetrabromobisphenol A (TBBPA) is the largest brominated flame retardant which can be released to environment and cause long-term hazard. In this work, we developed a rapid and highly sensitive fluorescence enzyme-linked immunosorbent assay (FELISA) for monitoring of TBBPA in soil samples. TBBPA specific nanobody derived from camelid was fused with alkaline phosphatase to obtain the bi-functional fusion protein, which enable the specific binding of TBBPA and the generation of detection signal simultaneously. The assay showed an IC50 of 0.23 ng g-1, limit detection of 0.05 ng g-1 and linear range from 0.1 to 0.55 ng g-1 for TBBPA in soil samples. Due to the high resistance to organic solvents of the fusion protein, a simple pre-treatment by using 40% dimethyl sulfoxide (DMSO) as extract solvent can eliminate matrix effect and obtain good recoveries (ranging from 93.4% to 112.4%) for spiked soil samples. Good relationship between the results of the proposed FELISA and that of liquid chromatography tandem mass spectrometry (LC-MS/MS) was obtained, which indicated it could be a powerful analytical tool for determination of TBBPA to monitor human and environmental exposure.

Coronaviruses are enveloped RNA viruses capable of causing respiratory, enteric, or systemic diseases in a variety of mammalian hosts that vary in clinical severity from subclinical to fatal. The host range and tissue tropism are largely determined by the coronaviral spike protein, which initiates cellular infection by promoting fusion of the viral and host cell membranes. Companion animal coronaviruses responsible for causing enteric infection include feline enteric coronavirus, ferret enteric coronavirus, canine enteric coronavirus, equine coronavirus, and alpaca enteric coronavirus, while canine respiratory coronavirus and alpaca respiratory coronavirus result in respiratory infection. Ferret systemic coronavirus and feline infectious peritonitis virus, a mutated feline enteric coronavirus, can lead to lethal immuno-inflammatory systemic disease. Recent human viral pandemics, including severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), and most recently, COVID-19, all thought to originate from bat coronaviruses, demonstrate the zoonotic potential of coronaviruses and their potential to have devastating impacts. A better understanding of the coronaviruses of companion animals, their capacity for cross-species transmission, and the sharing of genetic information may facilitate improved prevention and control strategies for future emerging zoonotic coronaviruses. This article reviews the clinical, epidemiologic, virologic, and pathologic characteristics of nine important coronaviruses of companion animals.

Botulinum neurotoxin (BoNT) serotype E is one of three serotypes that cause the preponderance of human botulism cases and is a Tier 1 Select Agent. BoNT/E is unusual among BoNT serotypes for its rapid onset and short duration of intoxication. Here we report two large panels of unique, unrelated camelid single-domain antibodies (VHHs) that were selected for their ability to bind to BoNT/E holotoxin and/or to the BoNT/E light chain protease domain (LC/E). The 19 VHHs which bind to BoNT/E were characterized for their subunit specificity and 8 VHHs displayed the ability to neutralize BoNT/E intoxication of neurons. Heterodimer antitoxins consisting of two BoNT/E-neutralizing VHHs, including one heterodimer designed using structural information for simultaneous binding, were shown to protect mice against co-administered toxin challenges of up to 500 MIPLD50. The 22 unique VHHs which bind to LC/E were characterized for their binding properties and 9 displayed the ability to inhibit LC/E protease activity. Surprisingly, VHHs selected on plastic-coated LC/E were virtually unable to recognize soluble or captured LC/E while VHHs selected on captured LC/E were poorly able to recognize LC/E coated to a plastic surface. This panel of anti-LC/E VHHs offer insight into BoNT/E function, and some may have value as components of therapeutic antidotes that reverse paralysis following BoNT/E exposures.

BackgroundThe variable domain of camelid heavy-chain antibodies (VHH) is increasingly being adapted to detect small molecules in various matrices. The insecticide carbaryl is widely used in agriculture while its residues have posed a threat to food safety and human health.ResultsVHHs specific for carbaryl were generated from an alpaca immunized with the hapten CBR1 coupled to keyhole limpet hemocyanin. An enzyme-linked immunosorbent assay (ELISA) based on the VHH C1 and the coating antigen CBR2-BSA was developed for the detection of carbaryl in cereals. This assay, using an optimized assay buffer (pH 6.5) containing 10% methanol and 0.8% NaCl, has a half-maximum signal inhibition concentration of 5.4 ng mL-1 and a limit of detection (LOD) of 0.3 ng mL-1 for carbaryl, and shows low cross reactivity (≤0.8%) with other tested carbamates. The LOD of carbaryl using the VHH-based ELISA was 36 ng g-1 in rice and maize and 72 ng g-1 in wheat. Recoveries of carbaryl in spiked rice, maize and wheat samples were in the range of 81-106%, 96-106% and 83-113%, respectively. Relative standard deviations of repeatability and intra-laboratory reproducibility were in the range of 0.8-9.2% and 2.9-9.7%, respectively.ConclusionThe VHH-based ELISA was highly effective in detecting carbaryl in cereal samples after simple sample extraction and dilution. © 2019 Society of Chemical Industry.

Polycystic liver is usually considered an incidental finding in human and veterinary medicine. Two unrelated adult llamas ( Lama glama) with a history of marked anorexia and weight loss were received for autopsy and diagnostic workup. The main gross change in the liver of both animals was multiple variably sized cysts randomly distributed throughout the parenchyma. Histologically, the cysts compressed the adjacent parenchyma and were lined by a single layer of cuboidal-to-columnar epithelium, surrounded by a fibrous collagen capsule. The lumen of the cysts contained finely granular-to-homogeneous basophilic material. The lining epithelium displayed strong immunoreactivity for pancytokeratin AE1/AE3 and cytokeratins 7, 8, 8/18, and 19, and was negative for vimentin, confirming the biliary epithelial origin of the cysts. No parasitic or infectious agents, or neoplastic changes, were detected. All other laboratory tests performed in both llamas were negative or non-diagnostic, suggesting that the congenital hepatic cysts described may have been at least partly responsible for clinical disease in both animals.

Lead identification and optimization are essential steps in the development of a new drug. It requires cost-effective, selective and sensitive chemical tools. Here, we report a novel method using nanobodies that allows the efficient screening for potent ligands. The method is illustrated with the cystic fibrosis transmembrane conductance regulator inhibitory factor (Cif), a virulence factor secreted by the opportunistic pathogen Pseudomonas aeruginosa. 18 nanobodies selective to Cif were isolated by bio-panning from nanobody-phage library constructed from immunized llama. 8 out of 18 nanobodies were identified as potent inhibitors of Cif enzymatic activity with IC50s in the range of 0.3-6.4 μM. A nanobody VHH219 showed high affinity (KD = 0.08 nM) to Cif and the highest inhibitory potency, IC50 = 0.3 μM. A displacement sandwich ELISA (dsELISA) with VHH219 was then developed for classification of synthetic small molecule inhibitors according their inhibitory potency. The developed assay allowed identification of new inhibitor with highest potency reported so far (0.16 ± 0.02 μM). The results from dsELISA assay correlates strongly with a conventional fluorogenic assay (R = 0.9998) in predicting the inhibitory potency of the tested compounds. However, the novel dsELISA is an order of magnitude more sensitive and allows the identification and ranking of potent inhibitors missed by the classic fluorogenic assay method. These data were supported with Octet biolayer interferometry measurements. The novel method described herein relies solely on the binding properties of the specific neutralizing nanobody, and thus is applicable to any pharmacological target for which such a nanobody can be found, independent of any requirement for catalytic activity.

Here we report the results of excavation and interdisciplinary study of the largest child and camelid sacrifice known from the New World. Stratigraphy, associated artifacts, and radiocarbon dating indicate that it was a single mass killing of more than 140 children and over 200 camelids directed by the Chimú state, c. AD 1450. Preliminary DNA analysis indicates that both boys and girls were chosen for sacrifice. Variability in forms of cranial modification (head shaping) and stable isotope analysis of carbon and nitrogen suggest that the children were a heterogeneous sample drawn from multiple regions and ethnic groups throughout the Chimú state. The Huanchaquito-Las Llamas mass sacrifice opens a new window on a previously unknown sacrificial ritual from fifteenth century northern coastal Peru. While the motivation for such a massive sacrifice is a subject for further research, there is archaeological evidence that it was associated with a climatic event (heavy rainfall and flooding) that could have impacted the economic, political and ideological stability of one of the most powerful states in the New World during the fifteenth century A.D.

ObjectiveTo describe the clinical, gross pathologic, and histopathologic findings for a visually impaired 5.8-year-old female alpaca with multiple ocular abnormalities, as well as the clinical findings for three closely related alpacas.Animals studiedFour alpacas.ProceduresOphthalmic examination was performed on a 16-month-old female alpaca following observation of visual impairment while hospitalized for an unrelated illness. Following acute systemic decline and death 4.5 years later, the alpaca's brain, optic nerves, and eyes were examined grossly and histologically. Ophthalmic examination of three closely related alpacas was subsequently performed.ResultsThe 16-month-old female alpaca (Alpaca 1) had ophthalmoscopic findings suggestive of a coloboma or hypoplasia of the retinal pigment epithelium (RPE) and choroid, and suspected optic nerve hypoplasia OU. Histopathology performed 4.5 years later revealed moderate to severe choroidal, RPE, and retinal hypoplasia with multifocal retinal detachments OU. However, the optic nerves were normal in size and histologic appearance when compared to an age-matched control. Clinical evaluation of the 2-year-old son of Alpaca 1 revealed iris colobomata OU and choroidal dysplasia/hypoplasia OD in addition to nonpathologic variations in melanin density including heterochromia iridis and a subalbinotic fundus OU. Clinical evaluation of the 13-year-old mother of Alpaca 1 revealed heterochromia iridis, cataracts, and a subalbinotic fundus OU. A 2-year-old half-brother of Alpaca 1 had an RPE and choroidal coloboma OS.ConclusionThe developmental ocular abnormalities diagnosed in these closely related alpacas are likely hereditary.

Coccidioidomycosis is a fungal disease caused by either Coccidioides immitis or Coccidioides posadasii. Anecdotal evidence suggests that camelids are particularly susceptible to this disease and that a relatively large percentage of pneumonias in these animals are caused by Coccidioides spp. In a search of 21 y (1992-2013) of records from the California Animal Health and Food Safety Laboratory, we found 79 cases of coccidioidomycosis diagnosed in camelids; 66 (84%) had pneumonia and 13 (16%) had lesions only in organs other than the lungs. The organs most frequently affected were lung (84%) and liver (78%). Coccidioides spp. were the cause of pneumonia in 66 of 362 (18%) camelid cases during the study period. The lesions in affected organs were multifocal-to-coalescing pyogranulomas, which in most cases were visible grossly. Ten of the 12 formalin-fixed, paraffin-embedded lung samples tested by a universal Coccidioides spp. PCR assay were positive (4 C. immitis, 2 C. posadasii); the species could not be determined in 4 of the 10 cases positive by PCR. Coccidioidomycosis is an important cause of pneumonia in camelids in California, and can be caused by either C. immitis or C. posadasii.

Streptococcus equi subspecies zooepidemicus septicemia of alpacas and llamas, also called alpaca fever, is characterized clinically by fever, depression, recumbency, and death, and pathologically by polyserositis. Although a few natural and experimental cases of the disease have been reported, very little information about the pathology of spontaneous cases has been published. We present a detailed gross and microscopic description of 3 spontaneous cases of alpaca fever and review the literature on this condition. Typical of spontaneous and experimental infections with S. equi ssp. zooepidemicus, the 3 animals had disseminated fibrinosuppurative polyserositis with vascular thrombosis and intralesional gram-positive cocci. In addition, 2 of the animals had severe fibrinosuppurative pneumonia, endocarditis, and myocardial necrosis; the third animal had transmural pleocellular enteritis with prominent lymphangitis. The enteric lymphangitis observed in the latter suggests that dissemination of S. equi ssp. zooepidemicus occurred through lymphatic circulation and that, at least in this animal, the portal of entry of infection was the alimentary system.

Identifying monoclonal antibodies that block human voltage-gated ion channels (VGICs) is a challenging endeavor exacerbated by difficulties in producing recombinant ion channel proteins in amounts that support drug discovery programs. We have developed a general strategy to address this challenge by combining high-level expression of recombinant VGICs in Tetrahymena thermophila with immunization of phylogenetically diverse species and unique screening tools that allow deep-mining for antibodies that could potentially bind functionally important regions of the protein. Using this approach, we targeted human Kv1.3, a voltage-gated potassium channel widely recognized as a therapeutic target for the treatment of a variety of T-cell mediated autoimmune diseases. Recombinant Kv1.3 was used to generate and recover 69 full-length anti-Kv1.3 mAbs from immunized chickens and llamas, of which 10 were able to inhibit Kv1.3 current. Select antibodies were shown to be potent (IC50

A VHH antibody (or nanobody) is the antigen binding fragment of heavy chain only antibodies. Discovered nearly 25 years ago, they have been investigated for their use in clinical therapeutics and immunodiagnostics, and more recently for environmental monitoring applications. A new and valuable immunoreagent for the analysis of small molecular weight environmental chemicals, VHH will overcome many pitfalls encountered with conventional reagents. In the work so far, VHH antibodies often perform comparably to conventional antibodies for small molecule analysis, are amenable to numerous genetic engineering techniques, and show ease of adaption to other immunodiagnostic platforms for use in environmental monitoring. Recent reviews cover the structure and production of VHH antibodies as well as their use in clinical settings. However, no report focuses on the use of these VHH antibodies to detect small environmental chemicals (MW < 1500 Da). This review article summarizes the efforts made to produce VHHs to various environmental targets, compares the VHH-based assays with conventional antibody assays, and discusses the advantages and limitations in developing these new antibody reagents particularly to small molecule targets. Graphical Abstract Overview of the production of VHHs to small environmental chemicals and highlights of the utility of these new emerging reagents.

BackgroundThere is limited information on the incidence of clinical signs, concurrent illness and treatment options for atrial fibrillation (AF) in New World Camelids (NWC).ObjectiveDescribe clinical signs and outcome of AF in NWC.AnimalsEight New World Camelids admitted with AF.MethodsA retrospective observational study of camelids diagnosed with AF based on characteristic findings on electrocardiogram (ECG).ResultsAll animals had an irregularly irregular heart rhythm detected on physical examination and 4 cases had obtunded mentation on admission. Three camelids were diagnosed with AF secondary to oleander intoxication, 3 animals had underlying cardiovascular disease, 1 was diagnosed with lone AF and 1 had AF diagnosed on examination for a urethral obstruction. Five of eight animals survived to discharge and nonsurvivors consisted of animals which died or were euthanized as a result of cardiovascular disease (2/8) or extra-cardiac disease unrelated to the AF (1/8).Conclusions and clinical importanceAtrial fibrillation occurs in NWC in association with cardiovascular disease, extra-cardiac disease or as lone AF. Amiodarone and transthoracic cardioversion were attempted in one llama with lone AF, but were unsuccessful. Atrial fibrillation was recorded in 0.1% of admissions.

The soluble epoxide hydrolase (sEH) is a potential pharmacological target for treating hypertension, vascular inflammation, pain, cancer, and other diseases. However, there is not a simple, inexpensive, and reliable method to estimate levels of active sEH in tissues. Toward developing such an assay, a polyclonal variable domain of heavy chain antibody (VHH) sandwich immunoassay was developed. Ten VHHs, which are highly selective for native human sEH, were isolated from a phage-displayed library. The ten VHHs have no significant cross-reactivity with human microsomal epoxide hydrolase, rat and mouse sEH, and denatured human sEH. There is a high correlation between protein levels of the sEH determined by the enzyme-linked immunosorbent assay (ELISA) and the catalytic activity of the enzyme in S9 fractions of human tissues (liver, kidney, and lung). The VHH-based ELISA appears to be a new reliable method for monitoring the sEH and may be useful as a diagnostic tool for diseases influenced by sEH. This study also demonstrates the broad utility of VHH in biochemical and pharmacological research.

We have produced three antitoxins consisting of the variable domains of camelid heavy chain-only antibodies (VH H) by expressing the genes in the chloroplast of green algae. These antitoxins accumulate as soluble proteins capable of binding and neutralizing botulinum neurotoxin. Furthermore, they accumulate at up to 5% total soluble protein, sufficient expression to easily produce these antitoxins at scale from algae. The genes for the three different antitoxins were transformed into Chlamydomonas reinhardtii chloroplasts and their products purified from algae lysates and assayed for in vitro biological activity using toxin protection assays. The produced antibody domains bind to botulinum neurotoxin serotype A (BoNT/A) with similar affinities as camelid antibodies produced in Escherichia coli, and they are similarly able to protect primary rat neurons from intoxication by BoNT/A. Furthermore, the camelid antibodies were produced in algae without the use of solubilization tags commonly employed in E. coli. These camelid antibody domains are potent antigen-binding proteins and the heterodimer fusion protein containing two VH H domains was capable of neutralizing BoNT/A at near equimolar concentrations with the toxin. Intact antibody domains were detected in the gastrointestinal (GI) tract of mice treated orally with antitoxin-producing microalgae. These findings support the use of orally delivered antitoxins produced in green algae as a novel treatment for botulism.

Tetrabromobisphenol A (TBBPA) is a ubiquitous flame retardant. A high-throughput immunoassay would allow for monitoring of human and environmental exposures as a part of risk assessment. Naturally occurring antibodies in camelids that are devoid of light chain, show great promise as an efficient tool in monitoring environmental contaminants, but they have been rarely used for small molecules. An alpaca was immunized with a TBBPA hapten coupled to thyroglobulin and a variable domain of heavy chain antibody (VHH) T3-15 highly selective for TBBPA was isolated from a phage displayed VHH library using heterologous coating antigens. Compared to the VHHs isolated using homologous antigens, VHH T3-15 had about a 10-fold improvement in sensitivity in an immunoassay. This assay, under the optimized conditions of 10% methanol in the assay buffer (pH 7.4), had an IC50 for TBBPA of 0.40 ng mL(-1) and negligible cross reactivity (

An antibody-based analytical method for the detection of a chemical flame retardant using antibody fragments isolated from an alpaca has been developed. One specific chemical flame retardant congener, 2,2',4,4'-tetrabrominated diphenyl ether (BDE-47), is often the major poly-BDE (PBDE) congener present in human and environmental samples and that which is the most frequently detected. An alpaca was immunized with a surrogate of BDE-47 covalently attached to a carrier protein. The resulting mRNA coding for the variable domain of heavy-chain antibodies (VHH) were isolated, transcribed to cDNA, and cloned into a phagemid vector for phage display library construction. Selection of VHHs recognizing BDE-47 was achieved by panning under carefully modified conditions. The assay sensitivity for detecting BDE-47 was down to the part-per-billion (microgram per liter) level. Cross-reactivity analyses confirmed that this method was highly selective for BDE-47 and selected hydroxylated metabolites. When exposed to elevated temperatures, the camelid VHH antibodies retained more reactivity than a polyclonal antibody developed to the same target analyte. The use of this VHH antibody reagent immobilized onto a Au electrode for impedance biosensing demonstrates the increased versatility of VHH antibodies.

Anti-idiotypic antibodies recognize the antigenic determinants of an antibody, thus they can be used as surrogate antigens. Single-domain antibodies from camlid heavy-chain antibodies with the benefit features of small size, thermostability, and ease in expression, are leading candidates to produce anti-idiotypic antibodies. In this work, we constructed an antibody phage library from the mRNA of an alpaca immunized with an antiaflatoxin monoclonal antibody (mAb) 1C11. Three anti-idiotypic VHH antibodies were isolated and applied to immunoassay toward aflatoxin as a coating antigen. The best immunoassay developed with one of these VHH antibodies shows an IC50 of 0.16 ng/mL toward aflatoxin B1 and cross-reactivity toward aflatoxin B2, G1, and G2 of 90.4%, 54.4%, and 37.7%, respectively. The VHH-based immunoassay was successfully applied to the analysis of peanuts, corn, and rice, which are the predominant commodities regularly contaminated by aflatoxins. A good correlation (r(2) = 0.89) was found between the data obtained from the conventional ELISA and the ELISA based on a VHH coating antigen for the analysis of aflatoxins in peanuts and feedstuff. The use of biotechnology in developing the surrogate, the absence of standard aflatoxin and organic solvents in the synthesis procedures, and the reproducibility of the VHH antibody makes it an ideal strategy for replacing conventional synthesized antigens.

Many of the neutralising antibodies, isolated to date, display limited activities against the globally most prevalent HIV-1 subtypes A and C. Therefore, those subtypes are considered to be an important target for antibody-based therapy. Variable domains of llama heavy chain antibodies (VHH) have some superior properties compared with classical antibodies. Therefore we describe the application of trimeric forms of envelope proteins (Env), derived from HIV-1 of subtype A and B/C, for a prolonged immunization of two llamas. A panel of VHH, which interfere with CD4 binding to HIV-1 Env were selected with use of panning. The results of binding and competition assays to various Env, including a variant with a stabilized CD4-binding state (gp120(Ds2)), cross-competition experiments, maturation analysis and neutralisation assays, enabled us to classify the selected VHH into three groups. The VHH of group I were efficient mainly against viruses of subtype A, C and B'/C. The VHH of group II resemble the broadly neutralising antibody (bnmAb) b12, neutralizing mainly subtype B and C viruses, however some had a broader neutralisation profile. A representative of the third group, 2E7, had an even higher neutralization breadth, neutralizing 21 out of the 26 tested strains belonging to the A, A/G, B, B/C and C subtypes. To evaluate the contribution of certain amino acids to the potency of the VHH a small set of the mutants were constructed. Surprisingly this yielded one mutant with slightly improved neutralisation potency against 92UG37.A9 (subtype A) and 96ZM651.02 (subtype C). These findings and the well-known stability of VHH indicate the potential application of these VHH as anti-HIV-1 microbicides.