Effect of hookworm infection and anthelmintic treatment on naturally acquired antibody responses against the GMZ2 malaria vaccine candidate and constituent antigens

Amoani et al. BMC Infectious Diseases (2021) 21:332 https://doi.org/10.1186/s12879-021-06027-5 RESEARCH ARTICLE Open Access Effect of hookworm infection and anthelmintic treatment on naturally acquired antibody responses against the GMZ2 malaria vaccine candidate and constituent antigens Benjamin Amoani1,2, Ben Gyan3, Samuel Asamoah Sakyi2*, Emmanuel Kwasi Abu4, Samuel Victor Nuvor5, Precious Barnes6, Tracy Sarkodie-Addo3, Benjamin Ahenkorah2,7, Christian Sewor1, Duah Dwomoh8, Michael Theisen9,10, Michael Cappello11, Michael D. Wilson12 and Bright Adu3 Abstract Background: Malaria and helminths diseases are co-endemic in most parts of sub-Saharan Africa. Immune responses from each of these pathogens interact, and these interactions may have implications on vaccines. The GMZ2 malaria vaccine candidate is a fusion protein of Plasmodium falciparum merozoite surface protein 3 (MSP3) and glutamate rich protein (GLURP R0). GMZ2 has recently showed modest efficacy in a phase IIb multicenter trial. Here, we assessed the effect of hookworm (Necator americanus) infection and anthelmintic treatment on naturally acquired antibody responses against GMZ2 and constituent antigens. Methods: This longitudinal cross-sectional study was conducted in the Kintampo North Municipality of Ghana. Blood and stool samples were taken from 158 individuals (4–88 years old) infected with either P. falciparum alone (n = 59) or both hookworm and P. falciparum (n = 63) and uninfected endemic controls (n = 36). Stool hookworm infection was detected by the Kato-Katz method and PCR. Malaria parasitaemia was detected by RDT, light microscopy and P. falciparum-specific 18S rRNA gene PCR. Serum samples were obtained prior to hookworm treatment with a single dose of albendazole (400 mg) and 3 weeks (21 days) after treatment. Levels of IgG1, IgG3 and IgM against GMZ2, MSP3 and GLURP R0 were measured by ELISA and compared among the groups, before and after treatment. Results: Participants with P. falciparum and hookworm co-infection had significantly higher IgG3 levels to GMZ2 than those with only P. falciparum infection and negative control (p < 0.05) at baseline. Treatment with albendazole led to a significant reduction in IgG3 levels against both GMZ2 and GLURP R0. Similarly, IgM and IgG1 levels against MSP3 also decreased following deworming treatment. (Continued on next page) * Correspondence: 2 Department of Molecular Medicine, School of Medical Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana Full list of author information is available at the end of the article © The Author(s). 2021 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Amoani et al. BMC Infectious Diseases (2021) 21:332 Page 2 of 8 (Continued from previous page) Conclusion: Individuals with co-infection had higher antibody responses to GMZ2 antigen. Treatment of hookworm/malaria co-infection resulted in a reduction in antibody responses against GMZ2 and constituent antigens after albendazole treatment. Thus, hookworm infection and treatment could have a potential implication on malaria vaccine efficacy. Introduction Malaria and hookworm are important parasitic diseases in humans, in terms of socio-economic impact and public health importance. Malaria is typically an acute disease; however, chronic asymptomatic infections may persist, particularly in adults living in endemic areas. Hookworm infection on the other hand is mainly chronic. In areas where these parasites are co-endemic and the transmission rates are high, co-infection is very common and this may influence morbidity and immune response against these infections [1–4], with possible implications on vaccine efficacy. The GMZ2 malaria vaccine candidate is a recombinant fusion protein, containing two blood-stage antigens of P. falciparum, GLURP R0 and MSP3 [5]. Previous phase 2 clinical trial of GMZ2 showed it well tolerated and immunogenic albeit with modest efficacy [5]. This is not uncommon since most malaria vaccine candidate efficacy trials in Africa has so far not been remarkably efficacious against malaria [6–11]. However, factors modulating immune responses against malaria vaccine candidates that may help provide possible explanations to the sub-optimal efficacies observed are not well understood. Helminths secrete immunomodulatory molecules to selectively skew or dampen immune responses to promote their longterm survival [12]. Hookworm infection is associated with higher levels of IL-10 and lower levels of both Th1 and Th2 cytokines [13]. The enhanced IL-10 production may be a mechanism to regulate pathology due to inflammatory responses elicited by the infection Hookworm infection is very common in Africa, however its effect on malaria vaccine candidate antigens such as GMZ2 have not been extensively investigated. Treatment of infected people with anthelmintic drug may alter antimalarial specific immune responses [1, 2, 14, 15]. Since albendazole treatment is administered to hookworm infected people who may be living in malaria endemic communities (exposed to both malaria and hookworm), it is important to determine if this chemotherapy alters any of the responses to malaria vaccine candidate antigens and inadvertently affect vaccine efficacy. We have previously shown that in the absence of other helminths, co-infection of hookworm with P. falciparum may modulate blood parasitemia levels and cytokine responses [16]. Different helminths modulate the immune response to malaria differently. Trichuris trichiura infections in malaria patients was associated with reduced antibody levels against P. falciparum antigens [3]. Similarly, Courtin et al., [17] found Schistosoma haematobium infection to be associated with reduction in IgG levels against P. falciparum antigens MSP-1 and GLURP. Gabonese children infected with Ascaris lumbricoides had a significantly higher P. falciparum antigametocyte antibody levels compared to non-infected children [4]. In (...truncated)