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Neutralizing antibody in Rodent Malaria
Abstract:
Small numbers of rat erythrocytes infected with viable P. berghei, when inoculated into susceptible rats together with hyperimmune rat serum (HIS), are fully neutralized. Serum from convalescent rats delays the onset of patency but does not neutralize. The neutralizing efficiency of HIS rises in proportion to the number of successive reinoculations of hyperimmune rats. In contrast, mice inoculated with parasites together with either HIS or normal rat serum succumbed to the disease at the same time after inoculation. Neutralization in rats occurs in vivo and is completed within 22 hours of inoculation. Much larger amounts of HIS are needed to achieve neutralization in splenectomized recipients than in intact rats. The action of HIS is dose-dependent. Thus, the degree of suppression of parasitaemia is proportional to the dose of HIS, while the mortality rate is inversely proportional to the dose. Suboptimal doses may even enhance the infection of recipient rats. The ability to produce neutralizing antibody is dissimilar in two strains of rat. Thus, the outbred Sabra strain produces neutralizing HIS, while the inbred Lewis rat is incapable of producing perceptible neutralizing antibody in our experimental model.
Insights
Hyperimmune rat serum (HIS) effectively neutralizes Plasmodium berghei infections in rats. However, this neutralizing antibody response varies between rat strains and is dose-dependent.
Area of Science:
- Immunology
- Parasitology
- Infectious Diseases
Background:
- Plasmodium berghei is a parasite that infects red blood cells.
- Hyperimmune rat serum (HIS) contains antibodies against P. berghei.
- Understanding immune responses to malaria parasites is crucial for developing treatments.
Purpose of the Study:
- To investigate the neutralizing capacity of hyperimmune rat serum (HIS) against Plasmodium berghei infections.
- To determine factors influencing the efficacy of HIS, including serum source, dosage, and host factors.
- To compare the immune response in different rat strains.
Main Methods:
- Inoculation of susceptible rats with P. berghei infected erythrocytes and HIS.
- Administration of HIS or normal rat serum to mice infected with P. berghei.
- Assessment of parasitemia and mortality rates.
- Comparison of HIS efficacy in intact versus splenectomized rats.
- Evaluation of HIS production in different rat strains (Sabra and Lewis).
Main Results:
- HIS fully neutralized P. berghei infections in rats, while convalescent serum only delayed patency.
- HIS neutralization was dose-dependent, with higher doses suppressing parasitemia and reducing mortality.
- Suboptimal HIS doses could enhance infection.
- Splenectomized rats required larger amounts of HIS for neutralization.
- The outbred Sabra rat strain produced neutralizing HIS, whereas the inbred Lewis rat strain did not.
Conclusions:
- HIS possesses significant in vivo neutralizing activity against P. berghei in rats.
- The production of neutralizing antibodies against P. berghei is strain-dependent in rats.
- HIS efficacy is influenced by dose, host immune status (splenectomy), and antibody concentration.