Commercial biologics produced by yeast

What are current the commercial biologics produced by yeast?

Saccharomyces cerevisiae, Escherichia coli, and mammalian cells are the most widely used host systems for biopharmaceutical protein production, accounting for 15%, 31%, and 43% of biopharmaceutical products developed, respectively.

The main strength of E. coli is its capacity for fast and hardy growth in bioreactors using simple media, although producing eukaryotic proteins in E. coli often results in inclusion body formation and/or low specific yields.

Mammalian cells are ideal for incorporating typical eukaryotic post translation modifications, such as glycosylation,however, the culture of mammalian cells is relatively slow, requires complex media, and is vulnerable to viral contaminations. As unicellular eukaryotic microbial host cells, yeast offers unique advantages in biopharmaceutical protein production.

The use of yeasts enables an ideal combination of hardy growth on simple media in large-scale bioreactors with the capacity of the desired post-translational modifications and feasibility in genetic manipulations.

Dozens of pharmaceutical products produced in S. cerevisiae including vaccines and blood factors have been marketed since the first industrial production of recombinant human insulin in S. cerevisiae in 1987, several of which are blockbusters

Here we summary a list of commercial biologics produced by yeast.

SystemProteinBrand NameTherapeutic area
S. cerevisiaeHepatitis (or plus other
infectious disease)
vaccines (I)
ComvaxH. influenzae type B and hepatitis B
infection in infants
RecombivaxHepatitis B
AmbirixHepatitis A and B
Pediarix8Various conditions inducing hepatitis B in children
Tritanrix-HBDiphtheria, tetanus, pertussis, and hepatitis B
Infanrix Hep B
Infanrix-PentaDiphtheria, tetanus, pertussis, polio, and hepatitis B
Infanrix-HexaDiphtheria, tetanus, pertussis, hepatitis B, polio, and H. influenzae
type B
ProcomvaxH. influenzae type B and hepatitis B
PrimavaxDiphtheria, tetanus, and hepatitis B
HBVaxProHepatitis B in children and adolescents
Lepirudin (S)RefludanHeparin-induced thrombocytopenia type I
Desirudin (S)RevascVenous thrombosis
Insulin (S)Actrapid, Velosulin,
Monotard, Insulatard,
Protaphane, Mixtard,
Actraphane, Ultratard
Diabetes mellitus
Insulin aspart (S)Novolog, Novolog
FlexPen, Novolog Penfill,
NovoRapid, NovoRapid
Penfill, Novomix 30,
Novolog mix 70/30
Insulin detemir (S)Levemir, Levemir
GLP-1 (S)VictozaType 2 diabetes
Glucagon (S) GlucaGenHypoglycemia
GM-CSF (S)LeukineCancer, bone marrow transplant
HGH (S)ValtropinDwarfism, pituitary turner syndrome
PDGF (I)RegranexLower extremity diabetic neuropathic ulcers
GEM 125Periodontal defects
HPV vaccine (I)GardasilCervical cancer caused by human
papillomavirus (HPV)
Rasburicase (I)Fasturtec, ElitexHyperuricemia
P. pastorisEcallantide (I)KalbitorHereditary angioedema
Insulin (S)InsugenType 2 diabetes
Human serum
albumin (S)
MedwayBlood volume expansion
Hepatitis vaccine (I) ShanvacHepatitis B
IFN-α 2b (S)ShanferonHepatitis C, cancer
Ocriplasmin (I)JetreaVitreomacular adhesion (VMA)
Anti-IL-6R Ab (I)Nanobody ALX-0061Rheumatoid arthritis
Anti-RSV Ab (S)Nanobody ALX00171Respiratory syncytial virus (RSV)
HB-EGF (I)Treatment of interstitial
cystitis/bladder pain syndrome
Collagen (I)Medical research reagents/dermal
H. polymorphaHBV vaccine (I)Hepavax-GeneHepatitis B
Y. lipolyticaPancrelipase (S)Creon, Ultresa, ViokaseExocrine pancreatic insufficiency

Ref: Yeast synthetic biology for the production of recombinant therapeutic proteins

Genetic and other difference among various yeast system

What are the main differences among various yeast system?

Saccharomyces cerevisiae is one of the best-characterized eukaryotes and most widely used host systems for biopharmaceutical production since the early days of genetic engineering and recombinant protein production.

Recently, nonconventional yeast species including Hansenula polymorpha, Pichia pastoris, Yarrowia lipolytica, Schizosaccharomyces pombe, and Kluyveromyces lactis have been developed as alternative hosts for the production of recombinant proteins.

Here we summary the main differences among various yeast system.

Yeast speciesAttributes
Saccharomyces cerevisiaeFavorable public acceptance
GRAS status
The most well studied of simple eukaryotes
Amenable to both classical genetics and modern recombinant DNA techniques
Versatile vector systems (episomal, integrative, copy-number regulated) are available (Invitrogen)
A wide range of mutant strains
Well-established fermentation and downstream processing
Hypermannosylation with immunogenic terminal _-1,3-linked mannose residues
Genome sequencing: Reference strain S288C; 12 157 Kb (6273 ORFs); Accession number PRJNA128
Pichia pastorisGRAS status
Tightly regulated, methanol-inducible AOX promoters
A Crabtree-negative yeast allowing for high dilution rates and high biomass yields in fermentation processes
Can grow rapidly on inexpensive media at high cell densities (up to 150 g DCW L_1)
Integrated vectors developed that help genetic stability of the recombinant elements, even in continuous and large-scale fermentation processes
Well-established commercial vector systems and host strains (Invitrogen)
A lesser extent of hypermannosylation compared to S. cerevisiae; No terminal _-1,3-linked mannose residues
Genome sequencing: Reference strain GS115; 9216 Kb (5040 ORFs); Accession number PRJNA39439, PRJEA37871
Hansenula polymorphaGRAS status
polymorpha Stringently regulated strong promoters (MOX, FMDH, etc.)
A Crabtree-negative yeast allowing for high dilution rates and high biomass yields in fermentation processes
Stable, multicopy integration of foreign DNA into chromosomal locations
Thermotolerant (growth up to 45 _C), resistant to heavy metals and oxidative stress
Can assimilate nitrates
A lesser extent of hypermannosylation compared to S. cerevisiae; No terminal _-1,3-linked mannose residues
Genome sequencing: Reference strain DL1; 9056 Kb (5325 ORFs); Accession number PRJNA60503
Schizosaccharomyces pombeAn oleaginous yeast, based on its ability to accumulate large amounts of lipids
GRAS status
Can grow in hydrophobic environments, that is able to metabolize triglycerides, fatty acids, n-alkanes, and n-paraffins as carbon sources for the bioremediation of environments contaminated with oil spills
Can secrete a variety of proteins via cotranslational translocation and efficient secretion signal recognition similar to higher eukaryotes
Availability of a commercial expression kit (YEASTERN BIOTECH CO., LTD.)
Salt tolerance
A lesser extent of hypermannosylation compared to S. cerevisiae; a lack of the immunogenic terminal _-1,3-mannose linkages
Genome sequencing: Reference strain CLIB122; 20 503 Kb (7042 ORFs); Accession number PRJNA12414
Kluyveromyces lactisA Crabtree-negative yeast allowing for high dilution rates and high biomass yields in fermentation processes
Lactose-fermenting present in milk and whey, and the strong, lactose inducible LAC4 promoter
Very high cell density (> 100 g DCW L_1)
Able to use both integrative and episomal expression vectors
An available easy-to-use reagent kit for K. lactis protein expression (New England Biolabs)
Terminal N-acetylglucosamine and no mannose phosphate
Genome sequencing: Reference strain NRRL Y-1140; 10 689 Kb (5502 ORFs); Accession number PRJNA12377

Ref: Yeast synthetic biology for the production of recombinant therapeutic proteins

Summary of recombinant biological molecules used Pichia pastoris for production

The P. pastoris has also been established as a versatile cell factory for the production of thousands of biomolecules both on a laboratory and industrial scale.

ProductUsed strainUsed vectorUsage
Lycopene and __caroteneX_33pGAPZAFeed supplements
PlectasinX_33pPICZ_AAntibacterial peptide
Bovine lactoferrinKM71HpJ902Transferrin and antibacterial protein
Bovine IFN__GS115pPIC9KPrevention and therapy of viral diseases
ApidaecinSMD1168pPIC9KAntibacterial peptide
hPAB__GS115pPIC9KAntibacterial peptide
Tachyplesin IGS115pGAPZ_BAntibacterial peptide
Snakin_1GS11pPIC9Antimicrobial peptide
PAF102X_33pGAPZAAntifungal peptide
Pisum sativumÊdefensin 1GS115pPIC9KAntifungal peptide
Class I chitinaseKM71HpPICZ_AAntifungal peptide
Ch_penaeidinKM71HpPIC9KAntimicrobial peptide
HispidalinGS115pPICZ_AAntimicrobial peptide
Fowlicidin_2X_33pPICZ_AAntimicrobial peptide
Parasin IX_33pPICZ_AAntimicrobial peptide
CecropinA_thanatinX_33pPICZ_AAntimicrobial peptide
Type I collagenConnective tissue
Human serum albuminGS115pPIC9KMaintaining osmolarity and carrier in blood
LegumainX_33pPICZ_ALysosomal protease
Goat chymosinX_33pPICZ_AHydrolysis of __casein
Carrot antifreeze proteinGS115pPIC9KInhibition of gluten deterioration
ProinsulinSuperMan5pPICZ_ATreatment of diabetes mellitus
hIFN__X_33, GS115, KM71H, CBS7435pPICZ_, pPIC9, pPpT4aSCritical cytokine for innate and adaptive immunity
IL_1_GS115, SMD1168, X_33pPICZ_AProinflammatory cytokine
IL_3X_33pPICZ_AMultipotent hematopoietic cytokine
IL_11GS115pPINK_HCThrombopoietic growth factor
IL_15X_33pPICZ_ADifferentiation and proliferation of T, B, and NK cells
Cyanate hydrataseGS115pPICZ_ADetoxification of cyanate and cyanide
Human antiplatelet scFv antibodyX_33pPICZ_ATreatment of atherosclerosis
__AmylaseX_33pPICZ_AStarch saccharification
Human epidermal growth factorGS115pPIC9KGeneration of new epithelial and endothelial cells
BromelainKM71HpPICZ_AOedematous swellings
Keratinocyte growth factorX_33pPICZ_AEpithelialization_phase of wound healing
TrypsinGS115pPIC9KHydrolysis of proteins in the digestive system
Human sialyltransferaseKM71HpPICZ_BPharmacological uses
TransglutaminaseGS115pPIC9KRestructured meat products
StreptokinaseX_33pPICZ_AThrombolytic medication
StaphylokinaseGS115, KM71HpPICZ_AThrombolytic medication

Table:Summary Of Recombinant Biological Molecules Used Pichia Pastoris For Production

Ref: Pichia pastoris: A highly successful expression system for optimal synthesis of heterologous proteins

Common Recombinant subunit vaccine expressed in Pichia pastoris

Subunit vaccines often suffer from poor immunogenicity and require certain helper molecules known as adjuvants to induce or enhance an appropriate immune response to the antigen. T‐cell activation is crucial in inducing protective immune responses. Antigens mannosylated by P. pastoris have shown to have enhanced antigen presentation and T‐cell activation properties compared with their nonglycosylated counterparts. Therefore, glycoproteins derived from P. pastoris have the potential to function as adjuvants.

Construct nameUsed strainUsed vectorTargeted disease
PIMP‐V1 and PIMP‐V2KM71pPICZαAMalaria
P1‐3CDPichiaPinkpPink‐HCHand–foot–mouth disease
Gp350GS115pPICZαAEBV infection
VP2–VP5–FcGS115pPIC9KInfectious bursal
F proteinGS115pPICZαANewcastle
OmpAGS115pPIC9KP. mirabilis infection
BoNT HcX‐33pPICZ‐ABotulism
Glycoprotein DGS115pPIC9KHSV‐2 infection

Table: Common Recombinant Subunit Vaccine Expressed In Pichia Pastoris

Ref: Pichia pastoris: A highly successful expression system for optimal synthesis of heterologous proteins

What are the common vector/plasmids used in the Pichia pastoris Protein expression system?

The expression of any recombinant gene in P. pastoris has three phase: (a) Cloning of a new gene into a suitable expression vector, (b) insertion of the cloned vector into P. pastoris host genome; and (c) trial of the potential different strains for the expression of the recombinant integrated gene.

What are the major components in the expression vector of P. pastoris?

The expression vectors in the P. pastoris expression system are one of the major components of this system. These vectors are composed of three sequences:

  • Promoter sequence (most often AOX1) in 5′ region
  • Transcriptional termination sequence in 3′ region which is essential in the processing and polyadenylation of messenger RNAs
  • Single or multiple cloning sites, necessary for the insertion of the gene of interest.

Why expression vector of Pichia pastoris need to be linearized?

The episomal vectors can replicate either autonomously in the cytoplasm or as part of a chromosome. But the vectors used in P. pastoris have no stable episomal status; therefore, they should first be linearized with enzymes and then be integrated into the P. pastoris chromosome.

Common plasmids used in the P. pastoris expression system to produce extracellular and intracellular proteins are listed in Tables 1 and 2, respectively.

Vector nameMarker geneUsed strainRecombinant protein
pPIC3.5KHis4, Kan, AmpKM71Maltooligosyltrehalose synthase
SMD1168Camellia sinensisÊheat shock protein
GS115Pleurotus ostreatusÊlaccases
GS115Rhizopus oryzaeÊLipase
GS115HSA/GH fusion protein
KM71Membrane protein
KM71Dengue virus envelope glycoprotein
pHIL_D2His4, AmpGS115Prostaglandin H synthase_2
GS115CatA1 and SODC
KM71RhodococcusÊnitrile hydratase

Table 1. Common Pichia pastoris expression vectors for the production of intracellular proteins

Vector nameMarker geneUsed strainRecombinant protein
pPIC9KHis4, Kan, AmpGS115Xylanase
GS115Porcine circovirus type 2
pPICZ_ShbleSMD1168Human chitinase
GS115Human topoisomerase I
GS115Human interferon gamma
X_33C_reactive protein
X_33Human RNase4
pHIL_S1His4, AmpGS115Rabies virus glycoprotein
GS115Rhizopus oryzaeÊLipase
KM71Camel lactoferricin
pGAPZ_ShbleGS115Acyl homoserine lactonase
SMD1168Variable lymphocyte receptor B
X_33Human gastric lipase
pJL_SXFLD1, AmpMS105Formaldehyde dehydrogenase
pBLHIS_SXHis4, AmpJC100Leukocyte protease inhibitor

Table 2. Common Pichia pastoris expression vectors for the production of secretory proteins

Ref: Pichia pastoris: A highly successful expression system for optimal synthesis of heterologous proteins

Representative SARS-CoV And MERS-CoV RBD-Specific Neutralizing Antibodies

Virus neutralizing antibodies induced by vaccines or infected virus play crucial roles in controlling viral infection. Currently developed SARS-CoV- and MERS-CoV-specific nAbs include monoclonal antibodies (mAbs), their functional antigen-binding fragment (Fab), the single-chain variable region fragment (scFv), or single-domain antibodies [nanobodies (Nbs)]. They target S1-RBD, S1-NTD, or the S2 region, blocking the binding of RBDs to their respective receptors and interfering with S2-mediated membrane fusion or entry into the host cell, thus inhibiting viral infections.

Representative SARS-CoV and MERS-CoV RBD-specific nAbs are summarized below.

Ab nameSourceNeutralizing activityNeutralizing mechanismProtective efficacyRefsb
HumanNeutralize human (strains GD03, Urbani, Tor2) and palm civet (strains SZ3, SZ16) SARS-CoV infectionRecognize epitopes (residues 408, 442, 443, 460, 475) on SARS-CoV S1 protein, interfering with RBD–ACE2 receptor interactionProtect mice against challenge of SARS-CoV (strains Urbani, rGD03, or rSZ16)[2]
HumanNeutralize human (Urbani, GZ02, CUHK-W1), palm civet (HC/SZ/61/03), and raccoon dog (A031G) SARS-CoV infectious clones containing S variantsInhibit the binding of SARS-CoV RBD–ACE2 receptorProtect mice against challenge of SARS-CoV infectious clones (Urbani, GZ02, HC/SZ/61/03) or mouse-adapted strain (MA15)[3]
scFv, mAb
HumanNeutralize live SARS-CoV (strain Urbani) infectionRecognize epitopes on SARS-CoV S1 (residues 261–672), blocking RBD–ACE2 binding and inhibiting syncytium formationNA[4]
scFv, mAb
HumanNeutralize live SARS-CoV (strain HKU-39849) infection; CR3022 could neutralize CR3014 escape variantsRecognize epitopes on SARS-CoV RBD (residues 318–510); CR3022 binds SARS-CoV-2 RBD with high affinityCR3014 protects ferrets against SARS-CoV (strain HKU-39849) infection[6]
MouseNeutralize human (strains GD03, Tor2) and palm civet (SZ3) pseudotyped SARS-CoV infectionRecognize epitopes on SARS-CoV RBD, blocking RBD–ACE2 receptor bindingNA[5]
mAbs, Fabs
HumanNeutralize divergent strains of pseudotyped and live (strain EMC2012) MERS-CoV infectionRecognize a number of key epitopes on MERS-CoV RBD protein, blocking RBD–DPP4 receptor bindingProphylactically and therapeutically prevent and treat MERS-CoV (strain EMC2012) challenge in hDPP4-Tg mice, rabbits, or common marmosets[7,8]
4C2 h
HumanizedNeutralize divergent strains of pseudotyped and live (strain EMC2012) MERS-CoV infectionRecognize epitopes (residues 510, 511, 553) on MERS-CoV RBD protein, blocking RBD–DPP4 receptor bindingPrevent MERS-CoV (strain EMC2012) challenge in Ad5/hDPP4-transduced or hDPP4-Tg mice[7]
MouseNeutralize pseudotyped and live (strain EMC2012) MERS-CoV infectionRecognize a number of key epitopes on MERS-CoV RBD protein, blocking RBD–DPP4 receptor bindingNA[7]
Dromedary camelNeutralizes live MERS-CoV (strain EMC2012) infectionRecognizes epitope (residue 539) on MERS-CoV RBD proteinProphylactically prevents MERS-CoV (strain EMC2012) challenge in hDPP4-Tg mice[8]
LlamaNeutralizes multiple strains of pseudotyped and live (strain EMC2012) MERS-CoV infectionRecognizes epitope (residue 539) on MERS-CoV RBD proteinProphylactically and therapeutically prevents and treats MERS-CoV (strain EMC2012) challenge in hDPP4-Tg mice[8]


[1]Neutralizing Antibodies against SARS-CoV-2 and Other Human Coronaviruses
[2]Potent cross-reactive neutralization of SARS coronavirus isolates by human monoclonal antibodies
[3]Structural basis for potent cross-neutralizing human monoclonal antibody protection against lethal human and zoonotic severe acute respiratory syndrome coronavirus challenge
[4]Potent neutralization of severe acute respiratory syndrome (SARS) coronavirus by a human mAb to S1 protein that blocks receptor association
[5]Cross-neutralization of human and palm civet severe acute respiratory syndrome coronaviruses by antibodies targeting the receptor-binding domain of spike protein
[6]Potent binding of 2019 novel coronavirus spike protein by a SARS coronavirus-specific human monoclonal antibody
[3]MERS-CoV spike protein: a key target for antivirals
[8]Advances in MERS-CoV vaccines and therapeutics based on the receptor-binding domain

Nanobody Engineering and strategies targeting the immune stroma of tumors.

In the last decade, cancer immunotherapies have produced impressive therapeutic results. However, the potency of immunotherapy is tightly linked to immune cell infiltration within the tumor and varies from patient to patient. Thus, it is becoming increasingly important to monitor and modulate the tumor immune infiltrate for an efficient diagnosis and therapy. Various bispecific approaches are being developed to favor immune cell infiltration through specific tumor targeting. The discovery of antibodies devoid of light chains in camelids has spurred the development of single domain antibodies (also called VHH or nanobody), allowing for an increased diversity of multispecific and/or multivalent formats of relatively small sizes endowed with high tissue penetration. The small size of nanobodies is also an asset leading to high contrasts for non-invasive imaging. The approval of the first therapeutic nanobody directed against the von Willebrand factor for the treatment of acquired thrombotic thrombocypenic purpura (Caplacizumab, Ablynx), is expected to bolster the rise of these innovative molecules.

Figure 1. Nanobody-based formats in development for tumor immunotherapy and imaging.
(A) Camelids specificity domains derived of conventional IgG1 or HcAbs (IgG2 and IgG3).
The nanobody crystal structure shown is pdb entry 6GZP. (B) Formats of nanobody engineered
molecules discussed in this review. Nb: nanobody; ARD: antigen recognition domain; TAA: tumor
associated antigen.
Figure 2. Nanobody-based strategies targeting the immune stroma of tumors. Nanobody-derived
immunomodulatory molecules are under investigation to increase anti-tumor immunity (orange
arrows) and prevent tumor-driven immune suppression (blue arrows). TAA: Tumor associated antigen;
IC: Immune checkpoint; ARD: Antibody recruiting domain.

Ref: Nanobody Engineering: Toward Next Generation Immunotherapies and Immunoimaging of Cancer. Antibodies (Basel). 2019 Jan 21;8(1):13. doi: 10.3390/antib8010013.

what are the unique features of nanobody and the applications

What are the unique features of nanobodies

Nanobody show some striking advantages versus conventional Abs that are noteworthy since they combine desirable features of mAbs with some of the beneficial properties of small molecule drugs.

  • They can bind a broad range of epitopes showing affinities in the nanomolar or even picomolar range. This implies that the affinities of Nbs are comparable or superior to those of conventional mAbs, reaching picomolar affinity constant range.
  • Possibility of formatting or multimerization. Given the small size and their monomeric nature of Nbs, they can be genetically engineered to obtain modular blocks that can be fused to form a new construct which will enable multispecificity and versatility.
  • They are highly stable and soluble. Nbs present optimal biophysical and biochemical properties including solubility, thermal tolerance, and proteolytic resistance. The folding of CDR3 loop and the hydrophilic content of the framework-2 region gives them high solubility in aqueous solutions and lack of aggregation.
  • Deep and fast tissue penetration and rapid blood clearance. Since passive intercellular diffusion rate within a tissue depends on the molecular size and is approximately inversely proportional to it, a 15-kDa monovalent Nb should improve the penetrability when compared with the performance of conventional mAbs (150 kDa).
  • Recognition of hidden epitopes. Crystallographic studies of conventional Abs have revealed that in most cases the Ag-binding surface is flat or concave.
  • Immunogenicity. Camelid VHH domains present high degree of homology with human VH domains, which means that to date they have not shown any unexpected immunogenicity reactions, which can be a potential concern for clinical applications
  • Production costs. mAbs are large multimeric proteins that usually undergo post-translational modifications. Hence, their production requires sophisticated machinery only found in eukaryotic systems.

Applications of nanobodies as diagnostic and therapeutic tools

  • Detection of proteins and microorganisms
  • Detection of small molecules
  • Imaging applications
  • Therapeutic tools

Nanobody production scheme using a phage display library. The genetic information can be obtained by active immunization using an
immunogen or using non-immunized animals by collection of blood which contains the lymphocytes. Increasing the diversity using semisynthetic libraries and randomly introducing amino acids in the CDR region is possible in order to improve the binding capabilities.
After the insertion of the plasmid in a bacterophage, the phagemid library is ready for this selection. Phage ELISA is the usual way to perform the biopanning. After the best candidate is selected, the production of the nanobody can be expressed in bacteria, yeast, or mammalian cells through its corresponding expression vector

Ref: Nanobody: outstanding features for diagnostic and therapeutic application. Anal Bioanal Chem. 2019 Mar;411(9):1703-1713. doi: 10.1007 s00216-019-01633-4. Epub 2019 Feb 8.

Single B Cell Cloning and Production of Rabbit Monoclonal Antibodies

Monoclonal antibodies are among the most significant biological tools used in medicine and biology that
have revolutionized the field of diagnostics, therapeutics, and targeted drug delivery systems for many
diseases. Among them, rabbit monoclonal antibodies have attracted significant attention for having high
affinity and specificity. During the past few decades, different techniques have been developed to produce
monoclonal antibodies. Single B cell cloning technology offers many advantages compared to other
methods and has been used to generate monoclonal antibodies from different species including rabbits.
This review briefly describes some of these methods, with main focus on single B cell cloning and
production of rabbit monoclonal antibodies.

Comparison between monoclonal and polyclonal antibodies
Diagram summarizing the generation of antigen-specific rabbit monoclonal antibodies by single B cell
cloning. PBMCs peripheral blood mononuclear cells, FACS fluorescence-activated cell sorting, RT-PCR reverse
transcription polymerase chain reaction, VH variable domain of heavy chain, VL variable domain of light chain,
LS leader sequence, HCD heavy-chain constant domain, LCD light-chain constant domain, HC heavy chain, LC
light chain, ELISA enzyme-linked immunosorbent assay

Ref: Single B Cell Cloning and Production of Rabbit Monoclonal Antibodies. Book: Genotype Phenotype Coupling pp 423-441

Genomic Basics

Human Genome

When someone refers to the genome, they often mean all of the information contained within an individual’s DNA. In fact, human genome actually refers to all of human DNA plus the proteins required to read and maintain it, as well as the many particles that help store and give shape to your DNA. Think of the entire genome as a library, and DNA as a genome encyclopedia.

DNA as a Genome Encyclopedia

The information in human genome encyclopedia is organized into about 21,000 gene chapters which are located within 23 chromosome volumes. Each individual has two nearly identical copies of each chromosome volume, one copy from each parent.

All of the entries in human genome encyclopedia are written in a special language—the DNA code. The DNA alphabet has only four letters, A, C, T, and G, representing the four different chemical bases. In total, each person has more than three billion DNA letters in each set of their 23 chromosomes.

The DNA Code

Although it may appear to be one long string of DNA letters, by studying the DNA code, researchers have learned that it also contains a complicated system of punctuation. Special codes signal when the DNA letters are part of a gene. Three letter combinations of DNA refer to specific amino acids. Within a gene, the amino acids provide instructions that can be read by special substances in the body to determine what type of protein needs to be made.

The order of all these DNA letters is called your genome sequence. When someone refers to your genome sequence, they mean the unique combination of DNA sequences from chromosome 1 through your sex chromosomes (XX or XY). Although we have two copies of each chromosome set, we only report one complete sequence.

This is because most of the DNA sequence is the same between the two chromosome sets. Whenever there are differences, this is noted in the person’s one, combined genome sequence. One person’s genome sequence is very similar to another’s. In fact, more than 99% of the human genome sequence is common to all people. This makes sense because we are all the same species (humans), and our bodies tend to have similar features (for example, two arms, two eyes, ten toes) and work in similar manners.