In vitro Survival and Retention of Infectivity of Plasmodium yoelii Sporozoites over Extended Periods of Time

SIu, Nikiforova; Sedegah, M.; Hoffman, Stephen L.

doi:10.2307/3283266

Cited by 3 publications

(6 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although each commercial positive agonist, such as TLR2 agonist LTA-BS, TLR3 agonist poly I:C, TLR4 agonist LPS, TLR5 agonist Flagellin, TLR7 agonist Gardiquimod TM and TLR9 agonist CpG ODN, could greatly activate the NF-κB reporter gene in TLR2, TLR4 or TLR5, TLR7 or TLR9-transfected cells and the IFN-β reporter gene in TLR3-transfected cells, SPZ lysate could only significantly activate TLR2-transfected cells, with over 2-fold of NF-κB reporter gene activity of the baseline ( P < 0.05 ). To investigate whether the activation of TLR2 by SPZ lysate is physiological relevance, the whole sporozoite lack of infectivity was prepared by placing in column buffer at 4 °C for more than 24 h as previously described 24 25 , and then stimulated the TLR2-transfected HEK293FT cells. As same as the lysate, the whole sporozoites could also induce more than 4 folds of NF-κB reporter activity as compared to the control ( Fig.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

The TLR2 is activated by sporozoites and suppresses intrahepatic rodent malaria parasite development

Zheng

Tan

Zhou

et al. 2015

Sci Rep

View full text Add to dashboard Cite

TLRs (Toll-like receptors) play an important role in the initiation of innate immune responses against invading microorganisms. Although several TLRs have been reported to be involved in the innate immune response against the blood-stage of malaria parasites, the role of TLRs in the development of the pre-erythrocytic stage is still largely unknown. Here, we found that sporozoite and its lysate could significantly activate the TLR2, and induce macrophages to release proinflammatory cytokines, including IL-6, MCP-1 and TNF-α, in a TLR2-dependent manner. Further studies showed that sporozoite and its lysate could be recognized by either TLR2 homodimers or TLR2/1 and TLR2/6 heterodimers, implicating the complexity of TLR2 agonist in sporozoite. Interestingly, the TLR2 signaling can significantly suppress the development of the pre-erythrocytic stage of Plasmodium yoelii, as both liver parasite load and subsequent parasitemia were significantly elevated in both TLR2- and MyD88-deficient mice. Additionally, the observed higher level of parasite burden in TLR2−/− mice was found to be closely associated with a reduction in proinflammatory cytokines in the liver. Therefore, we provide the first evidence that sporozoites can activate the TLR2 signaling, which in turn significantly inhibits the intrahepatic parasites. This may provide us with novel clues to design preventive anti-malaria therapies.

show abstract

Section: Resultsmentioning

confidence: 99%

“…Both sporozoite lysate and normal salivary gland lysate were prepared by repeated freezing and thawing of the purified sporozoites for four cycles. The whole sporozoites lack of infectivity were prepared by placing in medium at 4 °C for more than 24 h as previously described 24 25 .…”

Section: Methodsmentioning

confidence: 99%

The TLR2 is activated by sporozoites and suppresses intrahepatic rodent malaria parasite development

Zheng

Tan

Zhou

et al. 2015

Sci Rep

View full text Add to dashboard Cite

show abstract

“…stephensi mosquitoes will remain viable and retain infectivity at room temperature at least 36 hr after dissection if kept in M199 media with 5% normal mouse serum. 20 We used this method to transport P. falciparum, and although not specifically studied, it appeared that the parasites remained viable and did not lose significant infectivity during transport.…”

Section: Discussionmentioning

confidence: 99%

“…gambiae mosquitoes as previously described. 20 Sporozoite isolation was performed at the CDC Chamblee facility (Chamblee, GA). Once isolated, the sporozoites were transported at room temperature in M199 media containing 5% normal human serum (Gibco Laboratories, Grand Island, NY) directly to the Gorgas Memorial Laboratory in (Panama City, Republic of Panama).…”

Section: Monkeysmentioning

confidence: 99%

Susceptibility of Panamanian Aotus lemurinus lemurinus to sporozoite-induced Plasmodium falciparum (Santa Lucia) infection.

Ra¹,

Obaldía²,

Tr³

et al. 1999

The American Journal of Tropical Medicine and Hygiene

View full text Add to dashboard Cite

Abstract. Aotus monkeys are good models for erythrocyte-induced Plasmodium falciparum and P. vivax infections and have been extensively used in malarial drug and vaccine development. Recently, it has been shown that certain species of Aotus can be infected with sporozoites, and that the degree of susceptibility varies among species. We demonstrate here that Panamanian Aotus lemurinus lemurinus are susceptible to a sporozoite-induced infection, opening the possibility that this species of Aotus could be used as models for testing the efficacy of pre-erythrocytic P. falciparum vaccines and drug candidates directed at the pre-erythrocytic stages of P. falciparum and P. vivax malaria. In this species, we compared sporozoite infection rates. Two of four animals splenectomized prior to infection with sporozoites developed patent parasitemias. Seven of eight animals splenectomized either 7 or 35 days after infection became parasitemic. Additionally, we used a P. falciparum-specific polymerase chain reaction (PCR) method to detect the early appearance of parasitized erythrocytes in the blood prior to detection by conventional microscopy, and found that the parasitemia was detected first in five animals by the PCR method, first in three animals by blood film, with one parasitemia detected simultaneously. We also demonstrated the feasibility of infecting monkeys located in Panama with sporozoites isolated at an insectary in Atlanta, thus documenting the feasibility of similar studies where the insectary and monkey colony are not in the same location. A subsequent attempt to infect these monkeys using sporozoites was not successful, suggesting that this model of human malaria is not yet ready for routine use in vaccine or drug efficacy screening. This model merits further study because of the importance of testing pre-erythrocytic P. falciparum malaria vaccines and drugs in animals.Aotus species have long been used as an animal model for infection with erythrocytic stage Plasmodium falciparum. 1 Studies in Aotus have significantly contributed to the development of anti-malarial drugs suitable for human use, and, relatively recently, served as a model for the development and non-human testing of P. falciparum anti-malarial vaccines.2-13 Although Aotus can easily be infected with a variety of adapted erythrocytic strains of P. falciparum, 14 only the Santa Lucia strain of P. falciparum has consistently induced a sporozoite stage infection in a limited number of species of Aotus.15 Unfortunately the species of Aotus (A. lemurinus griseimembra) that has been reported to be highly susceptible to a Santa Lucia sporozoite infection is native to northern Colombia and the export of this species has been banned since 1973. Therefore, although an animal model exists for testing the efficacy of anti-malarial vaccines and drugs targeted at the sporozoite stage of P. falciparum, the paucity of a highly susceptible species of Aotus to a P. falciparum sporozoite infection outside of Colombia limits the usefulness of this model. The Aotus ...

show abstract

“…In addition to dosimetry, the 6-day hepatocyte attenuation assay, a biological measure used to confirm attenuation, was performed using irradiated PfSPZ without cryopreservation ( 26 ); the result of this assay, along with the dosimetry data, is incorporated into the lot release certificate of analysis for PfSPZ Vaccine.…”

Section: Radiochromic Film Mapping Of the Imtcmentioning

confidence: 99%

A First for Human Vaccinology: GMP Compliant Radiation Attenuation of Plasmodium falciparum Sporozoites for Production of a Vaccine Against Malaria

et al. 2022

View full text Add to dashboard Cite

Ionizing radiation (UV, X-ray and ɣ) administered at an appropriate dose to pathogenic organisms can prevent replication while preserving metabolic activity. We have established the GMP process for attenuation by ionizing radiation of the Plasmodium falciparum (Pf) sporozoites (SPZ) in Sanaria® PfSPZ Vaccine, a protective vaccine against malaria. Mosquitoes raised and infected aseptically with Pf were transferred into infected mosquito transport containers (IMTC) and ɣ-irradiated using a 60Co source. PfSPZ were then extracted, purified, vialed, and cryopreserved. To establish the appropriate radiation conditions, the irradiation field inside the IMTCs was mapped using radiochromic film and alanine transfer dosimeters. Dosimeters were irradiated for times calculated to provide 120-170 Gy at the minimum dose location inside the IMTC and regression analysis was used to determine the time required to achieve a lower 95% confidence interval for 150 Gy. A formula incorporating the half-life of 60Co was then used to construct tables of irradiation times for each calendar day. From the mapping studies, formulae were derived to estimate the minimum and maximum doses of irradiation received inside the IMTC from a reference dosimeter mounted on the outside wall. For PfSPZ Vaccine manufacture a dose of 150 Gy was targeted for each irradiation event, a dose known to completely attenuate PfSPZ. The reference dosimeters were processed by the National Institute of Standards and Technology. There have been 587 irradiation events to produce PfSPZ Vaccine during 13 years which generated multiple lots released for pre-clinical studies and clinical trials. The estimated doses at the minimum dose location (mean 154.3 ± 1.77 Gy; range 150.0-159.3 Gy), and maximum dose location (mean 166.3 ± 3.65 Gy, range 155.7 to 175.3 Gy), in IMTCs were normally distributed. Overall dose uniformity was 1.078 ± 0.012. There was no siginifcant change in measured dose over 13 years. As of January 2022, 21 clinical trials of PfSPZ Vaccine have been conducted, with 1,740 volunteers aged 5 months to 61 years receiving 5,648 doses of PfSPZ Vaccine totalling >5.3 billion PfSPZ administered. There have been no breakthrough infections, confirming the consistency and robustness of the radiation attenuation process.

show abstract

In vitro Survival and Retention of Infectivity of Plasmodium yoelii Sporozoites over Extended Periods of Time

Cited by 3 publications

References 6 publications

The TLR2 is activated by sporozoites and suppresses intrahepatic rodent malaria parasite development

The TLR2 is activated by sporozoites and suppresses intrahepatic rodent malaria parasite development

Susceptibility of Panamanian Aotus lemurinus lemurinus to sporozoite-induced Plasmodium falciparum (Santa Lucia) infection.

A First for Human Vaccinology: GMP Compliant Radiation Attenuation of Plasmodium falciparum Sporozoites for Production of a Vaccine Against Malaria

Contact Info

Product

Resources

About