Pangolin vs. BANAL
Test-tube binding scores do not tell the whole story!
Previous discussion about the role of Pangolin Coronaviruses as “footprints” in the SARS-COV-2 genome and the differences between them and those of Banal Bat Coronaviruses can be read here (Bostickson, 2021).
The complete background report reserved for the truly dedicated researcher can be consulted here (Bostickson 2025).
The Biological Reality Behind Human Cell Entry and Lung Infection
While the bat virus BANAL-20–52 clings tightly to receptors in a lab dish (Xu et al., 2025), the Pangolin-CoV-GD virus is the one that behaves like a real-world human illness. It enters human cells easily (Cantoni et al., 2022) and targets the respiratory system (Hou et al., 2023; Liang et al., 2023).
The Core Data: Binding vs. Entry
BANAL-20–52 holds a very tight chemical grip on human ACE2 receptors (Xu et al., 2025). Its binding score (\(K_{D}\)) is exceptionally low at around 1.6 to 4.2 nM (Xu et al., 2025). Pangolin-CoV-GD scores a much looser 13.6 nM (Wrobel et al., 2021; Xu et al., 2025). In biochemistry, a lower score means a tighter physical hold. By this single test-tube metric, the banal virus looks like a superior human match (Xu et al., 2025).
Real Biology (Living Tissue)
However, looking only at isolated binding scores creates a major blind spot (Cantoni et al., 2022; Hou et al., 2023; Wrobel et al., 2021). Full virus spike testing reveals that Pangolin-CoV-GD completely outperforms BANAL in real human cell environments (Cantoni et al., 2022). Pseudoviruses bearing the Pangolin-CoV-GD spike demonstrate hyper-efficient entry into human cells, performing 50 to 100 times better than the baseline Wuhan strain (Cantoni et al., 2022). This hyper-efficient entry is clearly visualized in Figures 3E–G (Cantoni et al., 2022).
Figure 3. Cantoni et al., (2022). Evolutionary remodeling of N‐terminal domain loops fine‐tunes SARS‐CoV‐2 spike https://link.springer.com/article/10.15252/embr.202154322
Four Reasons Pangolin-CoV-GD Mirrors SARS-CoV-2
A. Optimized Human Binding
The pangolin virus receptor-binding domain (RBD) shares 97% amino acid sequence identity with SARS-CoV-2 (Wrobel et al., 2021). Its physical structure is perfectly optimized to latch onto human ACE2 natively, requiring zero transitional mutations or evolutionary stepping stones to infect human tissue (Niu et al., 2021; Wrobel et al., 2021).
B. Hyper Efficient Cell Entry
Without a furin cleavage site, wild animal coronaviruses rely on internal cellular cathepsin enzymes to sneak inside. Pangolin-CoV-GD shows a unique pre-adaptation that makes it “oven-ready” for rapid human transmission compared to typical bat sarbecoviruses (Cantoni et al., 2022). This hyper-efficient behavior depends on its unique N-terminal domain (NTD) loops, which regulate spike stability and entry (Cantoni et al., 2022). Providing Wuhan-Hu-1 with the Pangolin CoV NTD directly enhances cell entry and phenocopies the Alpha variant (Cantoni et al., 2022).
C. High Immune Matching
Antisera and specific antibodies generated against SARS-CoV-2 potently cross-neutralize the pCoV-GD01 isolate (Huang et al., 2023). Their physical shapes and neutralizing epitopes match up so closely that pre-existing immunity to one offers strong cross-protection against the other (Huang et al., 2023).
D. Respiratory Pathology
Natural bat sarbecoviruses demonstrate an enteric tropism, meaning they live harmlessly in the gut of the animal (Hou et al., 2023; Liang et al., 2023; Yang et al., 2023). Pangolin-CoV-GD switches entirely to a respiratory profile. It replicates rapidly in primary human nasal (HNE) and large airway epithelial (LAE) cells, producing viral titers that exceed original SARS-CoV-2 levels (Hou et al., 2023). In transgenic K18-hACE2 mice, certain wild-type isolates trigger severe interstitial pneumonia, catastrophic weight loss, and systemic multi-organ infection identical to COVID-19 (Hou et al., 2023; Liang et al., 2023), though distinct lab derivatives can cause milder clinical symptoms while maintaining high lung replication (Liu et al., 2023).
The Role of NTD Loops in Hyper-Efficient Entry
A. The Power of the Pangolin NTD
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Scientists performed a “domain swap” by taking the NTD from the Pangolin CoV spike and pasting it onto the original Wuhan-Hu-1 spike (Cantoni et al., 2022). Adding the pangolin NTD gave the Wuhan strain a massive boost. It completely copied (“phenocopied”) the hyper-efficient cell entry seen in the highly infectious Alpha variant (Cantoni et al., 2022). When scientists did the opposite, putting the Wuhan NTD onto the Pangolin CoV spike , the virus could barely infect cells at all due to reduced spike stability and expression (Cantoni et al., 2022).
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B. The N1–5 Loops as Evolutionary Hotspots
The N1–5 loops on the virus spike are structural hotspots where genetic sequence and length vary widely across different sarbecoviruses (Cantoni et al., 2022). While original SARS-CoV-2 features particularly long loops (N2, N3, and N5), newer emerging human variants are actually evolving to make these specific loops shorter (Cantoni et al., 2022). The Pangolin CoV GD spike naturally possesses these shorter loops already (Cantoni et al., 2022). This structural layout regulates the physical stability of the spike, providing yet another demonstration that some animal sarbecoviruses require little to no adaptation to successfully penetrate human tissue (Cantoni et al., 2022).
Conclusion
In summary, test-tube data shows that the bat virus BANAL-20–52 has a tighter chemical grip on human cell receptors than Pangolin-CoV-GD. However, real-world tissue studies prove that chemical grip alone does not create a successful infection.
The Pangolin-CoV-GD virus is the one that possesses the complete biological package for human infection. It enters human cells 50 to 100 times more efficiently than early human COVID-19 strains, matches human immune profiles, and targets the lungs to cause severe respiratory disease. Because this pangolin virus achieves hyper-efficient human cell entry and lung infection natively without needing any evolutionary stepping stones, its spike highlights how a virus can be fully pre-adapted for human transmission, unlike any known BANAL coronavirus.
References
Bostickson, B. (2021, September 1). Banal versus pangolin: The final battle. Medium. https://billybostickson.medium.com/banal-versus-pangolin-the-final-battle-afb367293129
Bostickson, B. (2025, April). The pangolin (coronavirus) papers [Research report]. ResearchGate.https://www.researchgate.net/publication/390743356_The_Pangolin_Coronavirus_Papers
Cantoni, D., Mayora-Neto, M., Nageswaran, G., Da Costa, K. A., … & Wright, E. (2022). Evolutionary remodelling of N‐terminal domain loops fine‐tunes SARS‐CoV‐2 spike. https://link.springer.com/article/10.15252/embr.202154322
Hou, Y., Asakura, T., Nichols, G. E., … & Baric, R. S. (2023). Host range, transmissibility and antigenicity of a pangolin coronavirus. https://www.nature.com/articles/s41564-023-01476-x
Huang, W., Wu, J., … & Wang, J. (2023). A pangolin-origin SARS-CoV-2-related coronavirus: infectivity, pathogenicity, and cross-protection by preexisting immunity. https://www.nature.com/articles/s41421-023-00557-9
Liang, X., Chen, X., Zhai J., Li, X., Zhang, X., Zhang, Z., et al. (2023). Pathogenicity, tissue tropism and potential vertical transmission of SARSr-CoV-2 in Malayan pangolins. https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1011384
Liu, F., Chen, J., …. (2023). A SARS-CoV-2-Related Virus from Malayan Pangolin Causes Lung Infection without Severe Disease in Human ACE2-Transgenic Mice. https://journals.asm.org/doi/10.1128/jvi.01719-22
Niu, S., Wang, J., … & Gao, G. F. (2021). Molecular basis of cross‐species ACE2 interactions with SARS‐CoV‐2‐like viruses of pangolin origin. https://pmc.ncbi.nlm.nih.gov/articles/PMC8209949/
Wrobel, A. G., Benton, D. J., … & Gamblin, S. J. (2021). Structure and binding properties of Pangolin-CoV spike glycoprotein inform the evolution of SARS-CoV-2. https://pmc.ncbi.nlm.nih.gov/articles/PMC7864994/
Xia, Luo-Yuan; Xue-Feng Wang, Xiao-Ming Cui, Yi-Ming Zhang, … & Wu-Chun Cao. (2024). Characterization of a pangolin SARS-CoV-2-related virus isolate PCoV-GX/P2V in human cells and hACE2-transgenic mice. https://link.springer.com/article/10.1007/s11427-023-2484-x
Xu, C., … & Shi, Z. (2025). CX1/BtSY2 and BANAL-20–52 exhibit broader receptor binding and higher affinities to multiple animal ACE2 orthologs than SARS-CoV-2 prototype. https://journals.asm.org/doi/10.1128/jvi.00283-25
