Nanobodies have garnered significant attention in the fields of antibody-based drugs and cell therapies. Literature on the subject frequently mentions three specific animals—camels, alpacas, and llamas—raising the question of how to choose among them and what differences exist in their antibody sequences. These animals are detailed below: Camels, alpacas, and llamas all belong to the family Camelidae. This family comprises only three genera and six species, distributed across Asia and Africa (tribe Camelini) and South America (tribe Lamini). The Camelini tribe descended from a lineage that migrated from North America to Asia and Africa; these animals are large, possess humps, and are adapted to desert life. There are two to three extant species: the dromedary (*Camelus dromedarius*), the Bactrian camel (*Camelus bactrianus*), and the wild Bactrian camel (*Camelus ferus*). The dromedary, characterized by a single hump, is found in the Middle East and North Africa; while wild populations are extinct, some have become feral—such as the dromedaries introduced to Australia, which have established significant wild populations in the Australian desert. The Bactrian camel and the wild Bactrian camel represent the domesticated and wild forms of the two-humped species, respectively; distributed across Central Asia, the wild variety is distinguished by smaller humps, shorter fur, and longer limbs, and exists in very small numbers. The Lamini tribe descended from a lineage that migrated from North America to South America; these animals are smaller and lack humps, inhabiting the Andes mountains as well as the grasslands and semi-arid regions of southern South America. Within this group, the llama (*Lama glama*) and the alpaca (*Lama pacos*) are domesticated species that exhibit a wide variety of coat colors.
The classification of the Camelidae family is as follows:
● Camelus：
Camelus bactrianus
Camelus dromedarius
● Lama
Lama glama=Llama
Lama guanicoe
● Vicugna
Vicugna vicugna
Vicugna pacos=Alpaca=Lama pacos
Camels are the easiest to distinguish, the primary difference between alpacas and llamas lies in their size. Adult alpacas typically weigh around 60 kg, whereas llamas can weigh between 127 and 204 kg. Llamas have less hair on their legs, large banana-shaped ears, and shorter facial hair. In contrast, alpacas have thick hair on their legs, large, short, upright ears, and facial hair that is as thick as the hair on their bodies.
Among the three types of animals, camels exhibit the highest levels of single-domain antibodies—approximately 70%—whereas alpacas and llamas show levels ranging from about 25% to 45%. This is clearly evident from the PCR results of amplified VHH fragments and reflects the fact that it is easier to screen for nanobodies in camels.
Camelids possess both conventional IgG1 antibodies (comprising two heavy chains and two light chains) and single-domain heavy-chain antibodies; the latter consist solely of heavy chains and lack the CH1 constant domain.
Based on differences in the hinge region, antibodies from the Camelidae family can be classified into the following subtypes:
Among them, IgG2 and IgG3 are single-domain heavy-chain antibodies, the antibody subtypes in the three animal species are as follows:
● Alpaca：IgG1a，IgG1b，IgG2b，IgG2C
● Llama：IgG1a，IgG1b，IgG2b，IgG2C
● Camel：IgG1a，IgG1b，IgG2a，IgG2c，IgG3
Data from the IMGT database indicate the following:
● Camel (http://www.imgt.org/IMGTrepertoire/index.php?section=LocusGenes&repertoire=genetable&species=arabian_camel&group=IGHV): IGHV3S1 to IGHV3S41 correspond to conventional tetrameric IgG1; IGHV3S42 to IGHV3S74 correspond to single-domain heavy-chain antibodies (33 genes in total).
● Alpaca (http://www.imgt.org/IMGTrepertoire/index.php?section=LocusGenes&repertoire=genetable&species=Vicugna_pacos&group=IGHV): IGHV3-3 and IGHV3S53 to IGHV3S68 correspond to single-domain heavy-chain antibodies (17 genes in total).
● Llama (http://www.imgt.org/IMGTrepertoire/index.php?section=LocusGenes&repertoire=genetable&species=Llama&group=IGHV): IGHV3S1 to IGHV3S5 correspond to single-domain heavy-chain antibodies (5 genes in total).
Germline data indicate that camel antibodies exhibit greater diversity.
In the FR2 region of conventional antibodies, the four amino acid residues V42, G49, L50, and W52 participate in VL interactions; however, mutations occur at these four positions in VHH, as shown in the table below:
● Camel VHH FR2-amino acid positions
● Alpaca VHH FR2-amino acid positions
● Llama FR2-amino acid positions
In addition to the standard disulfide bond formed between positions 23 and 104, VHHs often feature an extra disulfide bond linking CDR1 or FR2 to CDR3. While this additional bond stabilizes the antibody structure, it frequently leads to disulfide bond mismatching during process development; furthermore, if the relevant residues are mutated, the antibody loses its activity. A review of Ablyx's patents reveals no sequences containing two pairs of disulfide bonds. Significant differences exist among camels, alpacas, and llamas regarding the location and prevalence of these additional disulfide bonds.
As previously mentioned, camels exhibit high levels of single-domain antibodies in their serum and possess a diverse germline repertoire; however, with the exception of IGHV3S42, the remaining 32 germline sequences contain an additional disulfide bond. For IGHV3S43 through IGHV3S71, this bond is located between CDR1 and CDR3, whereas for IGHV3S72 through IGHV3S474, it spans from amino acid position 50 in FR2 to the CDR3 region. NGS analysis of AlpVHHs' phage and yeast display-based naïve VHH libraries derived from *Camelus bactrianus* revealed that over 85% of the sequences contain two pairs of disulfide bonds.
Among the 17 alpaca germline sequences, eight contain two pairs of disulfide bonds, with the additional bond located between position 55 and the CDR3 region. NGS analysis of AlpVHHs' phage display-based naïve VHH libraries from alpacas showed that 32% of the sequences possess two pairs of disulfide bonds.
Of the five llama germline sequences, three contain two pairs of disulfide bonds, with the additional bond situated between position 55 and the CDR3 region. NGS analysis of AlpVHHs' phage display-based naïve VHH libraries from llamas indicated that 22.3% of the sequences have two pairs of disulfide bonds; this finding aligns with literature reporting that llamas exhibit the lowest frequency of such disulfide bonds among these three species.
The development of high-quality nanobodies relies not only on screening platforms but also on stable, traceable, and well-characterized animal resources.
At AlpVHHs, sustainability is embedded in everything we do—from the way we raise our alpacas to how we develop next-generation VHH antibodies. We believe scientific progress should not come at the cost of environmental or ethical compromise.
AlpVHHs has established a specialized camelid resource system and operates two dedicated animal farms housing over 800 Camelids (including alpacas, llamas, and camels), ensuring traceable and well characterized animal sources for the development of high-quality recombinant nanobodies (VHHs).
Through stable animal resources and standardized management, we provide animals with excellent traceability for VHH discovery.
AlpVHHs focuses on the discovery and development of VHH/single-domain antibodies (sdAbs) and Nanobody products, leveraging established technology platforms for Phage Display and Yeast Surface Display. Our main VHH product series includes Nanoselector, Recombinant Tag Antibody, Nano-Secondary Antibodiy, Recombinant Secondary Antibody, Smart Booster, and more. These products are widely applied in IP, IF, super resolution imaging, cell sorting, and antibody endocytosis detection.
Meanwhile our expert R&D team has over 10 years of experience in VHH field. We have collaborated with more than 300 biotech and biopharma companies, as well as universities, successfully delivering over 1,000 sdAb pre-discovery projects. Additionally, more than 20 collaborative projects have successfully progressed to IND approval.
