Biology subjects

Adair, A.

Publications and source records attributed to Adair, A..

7 recordsLinked to original sources

bioRxiv2026

Nanobodies against Plasmodium adhesins that block receptor engagement and malaria parasite invasion

Malaria is caused by Plasmodium parasites, and its clinical symptoms are a result of parasite invasion of red blood cells and the subsequent cycles of replication and proliferation. In human populations, Plasmodium vivax is responsible for the most widely distributed recurring malaria infections whereas Plasmodium falciparum inflicts the most mortality and morbidity. One well-characterized family of adhesins involved in red blood cell invasion is the reticulocyte-binding-like protein homolog family, known as the RBL superfamily which includes the PfRh family in P. falciparum and PvRBP family in P. vivax. Here we report a collection of nanobodies against three members of this adhesin family, PfRh5, PfRh4 and PvRBP2b. Nanobodies against these Plasmodium adhesins bind with high affinity across several epitopes and can block receptor engagement and inhibit parasite invasion of red blood cells. Using computational design, we generated stabilized PfRh4 variants that encompass the conserved scaffold present in the PfRh and PvRBP families of adhesins and show that several variants with improved expression retained binding to mouse monoclonal antibodies, nanobodies and Complement Receptor 1, the human receptor for PfRh4. We also observed that most of the inhibitory nanobodies against the three antigens recognized the conserved structural scaffold that define this family of adhesins. These results demonstrate the potential of nanobodies to block malaria parasite invasion into red blood cells.

microbiology↗

bioRxiv2025

Crystal structure and nanobodies against domain 3 of the malaria parasite fusogen Plasmodium falciparum HAP2

Malaria parasites are transmitted to humans through a bite from an infected female Anopheles mosquito. Within the mosquito midgut, malaria parasite gametes are activated and undergo fertilisation. If parasite fertilisation is perturbed, this stops the transmission of malaria parasites from mosquito to human. One proposed target of transmission-blocking interventions is Plasmodium falciparum fusogen PfHAP2, which is essential for gamete fusion during parasite fertilisation. However, to date, no monoclonal antibodies or structures of PfHAP2 have been generated. We have identified nanobodies that bind specifically to domain 3 of PfHAP2 with nanomolar affinities, two of which show some cross-species reactivity with HAP2 of other Plasmodium species. The crystal structure of one nanobody in complex with domain 3 of PfHAP2 provides the first structural insights into this transmission-blocking target in P. falciparum.

microbiology↗

bioRxiv2025

alpseq: an open-source workflow to turbocharge nanobody discovery with high-throughput sequencing

Nanobodies have emerged as promising tools for many biotechnological applications due to their small size, high stability, and remarkable binding specificity. Next-Generation Sequencing (NGS) enables deep profiling of large nanobody libraries and panning campaigns, however the scale and diversity of nanobody NGS datasets presents a significant bioinformatic challenge. To this end, we have developed alpseq, an optimised, open-source software pipeline designed specifically for the efficient and accurate processing of NGS data from nanobody libraries and panning campaigns. alpseq is also paired with a PCR-free sequencing library preparation protocol to allow researchers to easily generate their own data while avoiding biases. The alpseq software pipeline is composed of two parts: a pre-processing module written in Nextflow efficiently handles raw nanobody reads in a single line of code. These results are then fed into the analysis module, which contains a comprehensive suite of functions for quality control, diversity analysis, identification of enriched sequences and clustering. alpseq also creates a user-friendly interactive report which empowers scientists to explore their data without the need for extensive bioinformatic experience. Sophisticated panning campaign designs are supported, such as replicates and comparisons between different pans to find cross-binding leads. alpseq thus generates insights into the nanobody selection process and delivers a list of lead candidates for further experimental validation and downstream applications. alspeq is available at https://github.com/kzeglinski/alpseq.

bioinformatics↗

bioRxiv2025

Pfs48/45 nanobodies block Plasmodium falciparum transmission

Malaria parasite fertilisation occurs within the Anopheles mosquito midgut. Interventions that inhibit parasite fertilisation prevent ongoing transmission and are important for malaria elimination efforts. Pfs48/45 and Pfs230 are two leading transmission-blocking vaccine candidates. Both proteins form a complex on the surface of sexual stage parasites and are essential for male fertility. Here we have identified nanobodies against Pfs48/45 that recognise gametocytes and have strong transmission-reducing activity. The crystal structure of our most potent nanobody in complex with Pfs48/45 reveals it binds a distinct epitope to TB31F, a leading transmission-blocking monoclonal antibody. In addition, we generated bispecific nanobodies that can target both Pfs48/45 and Pfs230 simultaneously and are fused to a human Fc domain. Our results show that these bispecific nanobodies recognise both Pfs48/45 and Pfs230 and reduce malaria parasite fertilisation in Anopheles stephensi. These results demonstrate the potential of nanobodies as a versatile antibody format that can reduce malaria transmission. Author SummaryMalaria is spread when an infected Anopheles mosquito bites a human. Within the female Anopheles mosquito, malaria parasite fertilisation occurs in the mosquito midgut. If you inhibit parasite fertilisation in the mosquito, you can prevent onward transmission of the malaria parasite from mosquito to humans. Transmission blocking vaccines work by stopping parasite fertilisation and development in the mosquito and are key for malaria elimination by preventing community spread. Pfs48/45 and Pfs230 are two leading transmission-blocking vaccine candidates, and both are critical for male fertility. Here we describe the generation of nanobodies that target Pfs48/45. We show that when nanobodies against Pfs48/45 were added to infected blood meals for Anopheles mosquitoes, the nanobodies significantly reduced parasite transmission. In addition, we generated bispecific nanobodies that target both Pfs48/45 and Pfs230 and these bispecific nanobodies also significantly reduced oocyst development. Our work demonstrates the potential of nanobodies as a versatile antibody format that can reduce malaria transmission.

microbiology↗

bioRxiv2025

Cryo-EM structure of endogenous Plasmodium falciparum Pfs230 and Pfs48/45 fertilization complex

Plasmodium falciparum Pfs230 and Pfs48/45, part of a core fertilization complex, are leading malaria transmission-blocking vaccine candidates. However, how the two proteins interact is unknown. Here we report a 3.36 [A] resolution cryo-electron microscopy structure of the endogenous Pfs230-Pfs48/45 complex. We show that Pfs48/45 interacts with Pfs230 domains 13 and 14, domains that are not included in current Pfs230 vaccine immunogens. Using a transgenic parasite line with a domain 13 to 14 deletion, we show that these domains are essential for Pfs230 localization on the gamete surface. Furthermore, this line significantly reduced oocyst formation in the mosquito midgut, showing that the presence of Pfs230 domains 13 and 14 is critical for successful fertilization. Nanobodies against domains 13 and 14 inhibit Pfs230-Pfs48/45 complex formation, reduce transmission and structural analyses reveal their binding epitopes. Furthermore, domains 13 and 14 are targets of naturally acquired immunity and when delivered as mRNA-LNP immunizations induce potent immune responses and blocked transmission of malaria parasites. Our comprehensive structural insights on a core P. falciparum fertilization complex will guide the design of novel transmission-blocking vaccine candidates against malaria.

microbiology↗

bioRxiv2020

Nanobody generation and structural characterization of Plasmodium falciparum 6-cysteine protein Pf12p

Surface-associated proteins play critical roles in the Plasmodium parasite life cycle and are major targets for vaccine development. The 6-cysteine (6-cys) protein family is expressed in a stage-specific manner throughout Plasmodium falciparum life cycle and characterized by the presence of 6-cys domains, which are {beta}-sandwich domains with conserved sets of disulfide bonds. Although several 6-cys family members have been implicated to play a role in sexual stages, mosquito transmission, evasion of the host immune response and host cell invasion, the precise function of many family members is still unknown and structural information is only available for four 6-cys proteins. Here, we present to the best of our knowledge, the first crystal structure of the 6-cys protein Pf12p determined at 2.8 [A] resolution. The monomeric molecule folds into two domains, D1 and D2, both of which adopt the canonical 6-cys domain fold. Although the structural fold is similar to that of Pf12, its paralog in P. falciparum, we show that Pf12p does not complex with Pf41, which is a known interaction partner of Pf12. We generated ten distinct Pf12p-specific nanobodies which map into two separate epitope groups; one group which binds within the D2 domain, while several members of the second group bind at the interface of the D1 and D2 domain of Pf12p. Characterization of the structural features of the 6-cys family and their associated nanobodies provide a framework for generating new tools to study the diverse functions of the 6-cys protein family in the Plasmodium life cycle.

microbiology↗

bioRxiv2018

Patterns of recurrence after curative-intent surgery for pancreas cancer reinforce the importance of locoregional control and adjuvant chemotherapy.

IntroductionThe pattern of recurrence after surgical excision of pancreas cancer may guide alternative pre-operative strategies to either detect occult disease or need for chemotherapy. This study investigated patterns of recurrence after pancreatic surgery.\n\nMethodsRecurrence patterns were described in a series of resected pancreas cancers over a 2-year period and recurrence risk expressed as odds ratio (OR) with 95% confidence interval (C.I.). Survival was displayed by Kaplan-Meier curves.\n\nResultsOf 107 pancreas resections, 69 (65%) had pancreatic cancer. R0 resection was achieved in 21 of 69 (30.4%). Analysis was based on 66 patients who survived 30 days after surgery with median follow up 21 months. Recurrence developed in 41 (62.1%) patients with median time to first recurrence of 13.3 months (interquartile range 6.9, 20.8 months). Recurrence site was most frequently locoregional (n=28, 42%), followed by liver (n=23, 35%), lymph nodes (n=21, 32%), and lungs (n=13, 19%). In patients with recurrence, 9 of 41 had single site recurrence; the remaining 32 patients had more than one site of recurrence. Locoregional recurrence was associated with R+ resection (53% vs 25% for R+ vs R0, respectively; OR 3.5, 95% C.I. 1.1-11.2; P=0.034). Venous invasion was associated with overall recurrence risk (OR 3.3, 95% C.I. 1.1-9.4; P=0.025). In multivariable analysis, R-stage and adjuvant chemotherapy predicted longer survival.\n\nDiscussionThe predominant locoregional recurrence pattern, multiple sites of recurrence and a high R+ resection rate reflect the difficulty in achieving initial local disease control.

pathology↗