Naturally acquired antibodies to Plasmodium falciparum are known to play a key role in immunity against malaria
[1, 2]. However, it is still unclear which antibody responses are important in protection from disease despite a number of immunoepidemiology studies that have attempted to answer this question.
What is the infective stage of the Plasmodium life cycle?
The malaria parasite life cycle involves two hosts. During a blood meal, a malaria-infected female Anopheles mosquito inoculates sporozoites into the human host .
Sporozoites infect liver cells and mature into schizonts , which rupture and release merozoites
.
What are the three stages in the life cycle of Plasmodium?
[A]
Human liver stages (exo-erythrocytic cycle )
(1) The female anopheles mosquito injects parasites (sporozoites) into the human after a blood meal. Sporozoites travel into the bloodstream to the liver. (2) Sporozoites invade the liver cells (hepatocytes). (3) Sporozoites mature into schizonts.
What are the stages of Plasmodium?
Of the many forms the malaria parasite takes during its complex life cycle, three stages must invade host cells;
the ookinete, the sporozoite and the merozoite
(see Fig. 1 for an overview of the life cycle of the malaria parasite).
How does the immune system response to Plasmodium?
An innate immune response is triggered during Plasmodium infection as first line of defense, followed by an adaptive immune response, which includes T-cells, B-cells, and antibodies
. A mosquito inoculates Spz into a host’s skin when biting; these can remain in the skin for up to 6 h after inoculation (40).
How do antibodies differ from each other?
Antibodies from different classes also differ
in where they are released in the body and at what stage of an immune response
. Together with B and T cells, antibodies comprise the most important part of the adaptive immune system.
Which among the following stage of Plasmodium is the infective stage for humans and is introduced into the human body by the bite of female Anopheles?
The infective stage of plasmodium to man is
sporozoite
. The sporozoites are small, spindle – shaped, slightly curved and uninucleate organisms.
What is the first infective stage of malarial parasite in man?
The stage infective for humans is the
uninucleate, lancet-shaped sporozoite
(approximately 1 × 7 μm). Sporozoites are produced by sexual reproduction in the midgut of vector anopheline mosquitoes and migrate to the salivary gland.
What is the ring stage of Plasmodium?
Ring-form trophozoites (rings) of Plasmodium falciparum are
often thin and delicate, measuring on average 1/5 the diameter of the red blood cell
. Rings may possess one or two chromatin dots. They may be found on the periphery of the RBC (accolé, appliqué) and multiply-infected RBCs are not uncommon.
What is the diagnostic stage of Plasmodium?
Malaria parasites can be identified by
examining under the microscope a drop of the patient’s blood, spread out as a “blood smear” on a microscope slide
. Prior to examination, the specimen is stained (most often with the Giemsa stain) to give the parasites a distinctive appearance.
What is the life cycle of parasites?
All parasites have a life cycle that involves
a period of time spent in a host organism and that can be divided into phases of growth, reproduction, and transmission
. Life cycles of parasites can be further divided into two categories: direct (monoxenous) and indirect (heteroxenous).
What is the trophozoite stage of Plasmodium?
A trophozoite (G. trope, nourishment + zoon, animal) is
the activated, feeding stage in the life cycle of certain protozoa such as malaria-causing Plasmodium falciparum and those of the Giardia group
. (The complement of the trophozoite state is the thick-walled cyst form).
What are two phases of life cycle of Plasmodium falciparum?
This study investigates the response of dendritic cells to two different life stages of the malaria parasite,
parasitized red blood cells and merozoites
, using a murine model.
What is the infective stage of Plasmodium falciparum in man?
The human-infective stage are
sporozoites from the salivary gland of a mosquito
. The sporozoites grow and multiply in the liver to become merozoites.
How do antibodies fight malaria?
Antibodies
block invasion of sporozoites into liver cells
. IFN-y and CD8 T cells inhibit parasite development in hepatocytes. Antibodies block invasion of merozoites into erythrocytes. Antibodies prevent sequestration of infected erythrocytes by preventing binding to adhesion molecules on the vascular endothelium.
How long do malaria antibodies last?
A model to explain cross-sectional age-specific serological profiles indicates that low levels of antibodies may be maintained for
many years after infection
(11), and early studies using crude malaria antigen preparations also indicated that antibodies can be detected for some years after infection (4, 9).
Which of the following are actions of antibodies?
Examples of antibody functions include
neutralization of infectivity, phagocytosis, antibody-dependent cellular cytotoxicity (ADCC), and complement-mediated lysis of pathogens or of infected cells
.
When are antibodies produced and why?
The immune system cells produce antibodies
when they react with foreign protein antigens, such as infectious organisms, toxins and pollen
. At any given time, the body has a large surplus of antibodies, including specific antibodies that target thousands of different antigens.
Which of the following produces antibodies?
The correct answer is
Lymphocyte
. A lymphocyte is a type of white blood cell that is part of the immune system.
Which one is infectious stage of Plasmodium?
The
human infection
starts when an infected female anopheles’ mosquito bites a human and injects infected with sporozoites saliva into the blood flow. That is the initial living stage of plasmodium (period of infection).
What is the infective stage of malarial parasite class 12?
while feeding on human blood, the infective stage,
the sporozoites
are transferred from mosquito to man. The sporozoites go to the human liver for multiplication which turns into merozoites and attacks human RBC. So, the correct answer is, ‘sporozoites’.
Which of the following stage of Plasmodium will not be seen in human?
So, the correct answer is ‘
Merozoite
‘.
