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Evolutionary Biology of Parasitism
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
However, other experimental results suggest a more nuanced and opposite effect. Consider Plasmodium chabaudi, a mosquito-transmitted parasite of mice. Serial syringe passage results in parasites with high levels of virulence that cause high levels of parasitemia in red blood cells (Figure 7.17A). The faster growing forms would come to predominate and be favored by artificial syringe transfer of infected blood to uninfected mice. This idea has been called the short-sighted hypothesis. The predominance of more rapidly reproducing (virulent) strains might be expected to translate into their greater transmission success to mosquitoes, if mosquitoes happen to be present. Otherwise, the virulent parasites might simply cause the early death of their host, hence the notion that such an approach is “short-sighted.” However, when P. chabaudi was allowed to infect its Anopheles mosquito vector and mouse infections were initiated by bites of infected mosquitoes, a significantly reduced level of parasitemia and virulence in mice was noted (Figure 7.17A). Passage through the vector had the effect of modifying expression of members of the pir gene family in asexual blood stage parasites in the mice. This in turn altered the mouse immune response and lead to attenuation of parasite growth and pathology.
Use of Artemisia annua L. in the Treatment of Diseases—An Update
Published in Tariq Aftab, M. Naeem, M. Masroor, A. Khan, Artemisia annua, 2017
M. Naeem, Tariq Aftab, Asfia Shabbir, M. Masroor, A. Khan
A report on the use of A. annua L. infusion for malaria prevention by a Ugandan community states that around 60% of the 350 million annual cases of clinical malaria and 80% of deaths due to malaria occur in sub-Saharan Africa (world malaria report, 2005). Malaria and related fevers are major causes of poverty, work absenteeism, and poor performance in schools (Vitor-Silva et al., 2009). Other plants of this family that do not contain artemisinin, such as A. absinthium, A. herba‑alba, A. apiacea, A. ludoviciana, A. abrotanum , and particularly A. afra , have excellent antimalarial properties. The latter is widely used for this application in South Africa and Tanzania. A dose of 24 mg/kg of Artemisia powder was much more effective in reducing parasitemia in mice infected with Plasmodium chabaudi than an equivalent dose of pure artemisinin (Elfawal et al.,2012). The Worcester Institute reported that the consumption of dried whole plant A. annua delayed the appearance of malaria drug resistance and overcame resistance to artemisinin (Elfawal et al., 2014; Weathers et al., 2014).
Idiyotype Vaccines
Published in F. Y. Liew, Vaccination Strategies of Tropical Diseases, 2017
Marilyn J. Moore, Juraj Ivanyi
In a recent series of experiments, an anti-Id recognizing a protective monoclonal antibody for Plasmodium chabaudi was produced and characterized.47 The anti-Id which was raised in rabbits was found to recognize antigen combining site-related idiotopes on the monoclonal antibody and was shown to protect mice from homologous infection in vivo. The protection compared favorably with that observed after immunization with the purified antigen recognized by the monoclonal antibody (Figure 3). Furthermore, in naive mice, a crude antigen preparation and the anti-Id were shown to induce T cells reactive with the parasite although it was not clear whether these T cells were functional in protection.
Repeated vaccination and ‘vaccine exhaustion’: relevance to the COVID-19 crisis
Published in Expert Review of Vaccines, 2022
Md Anwarul Azim Majumder, Mohammed S. Razzaque
The negative impact of prior immunization on the effectiveness of subsequent vaccination was first observed in British boarding schools by Hoskins et al. and is commonly known as the ‘Hoskins effect’ [11]. The phenomenon has been evidenced in a number of subsequent studies of flu vaccines. For example, the multiyear Canadian Vaccine Effectiveness Network data showed reduced effectiveness in individuals with prior flu vaccination [12]. Importantly, the reduced vaccine effectiveness was more pronounced when identical vaccines were repeated, but the currently circulating virus was a poor antigenic match [12]. In an experimental study, a vaccine developed for the malaria parasite Plasmodium chabaudi showed reduced effectiveness in the absence of parasitic evolution in a serial passage experiment on mice [13].
Can Plasmodium’s tricks for enhancing its transmission be turned against the parasite? New hopes for vector control
Published in Pathogens and Global Health, 2019
S. Noushin Emami, Melika Hajkazemian, Raimondas Mozūraitis
A study using mice malaria-mosquito system revealed that mice at the chronic stage harboring relatively high levels of Plasmodium chabaudi (clone AS) gametocytes emitted significantly larger amounts of N,N-dibutylformamide, tridecane, 2-pyrrolidone, 2-hexanone, 2-methyl-butanoic acid, 2-phenyl ethanol and two unidentified compounds. In addition, amounts of two acids, namely 3-methyl butanoic and hexanoic acids tend to differ from the emissions of infected versus uninfected mice. It is interesting to note that in the 3 months after initial infection, volatile collections showed a decrease in overall volatile emissions from infected mice during the early, acute stage of infection compared to healthy controls as well as periodic cycles of elevated volatile emissions which corresponded to increase attractiveness of mice to mosquitoes [30].
Multi-functional antibody profiling for malaria vaccine development and evaluation
Published in Expert Review of Vaccines, 2021
D. Herbert Opi, Liriye Kurtovic, Jo-Anne Chan, Jessica L. Horton, Gaoqian Feng, James G. Beeson
A role for complement in immunity to malaria is also supported by evidence from some animal models. C1q-deficient mice were found to effectively control primary acute infection with Plasmodium chabaudi chabaudi similar to wild-type mice but were significantly more susceptible to secondary infection suggesting a greater role for complement in immunity during re-infection [135]. Antibodies, against a glycan α-gal expressed by Plasmodium spp were shown to confer protection in mice against Plasmodium berghei ANKA in a complement-dependent manner [136].