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Antigenic repertoire of Plasmodium vivax transmission-blocking vaccine candidates from the Indian subcontinent.

Prajapati SK, Joshi H, Dua VK - Malar. J. (2011)

Bottom Line: Majority of the amino acid substitutions observed in Indian isolates were more identical to the substitutions reported from isolates of Thailand and Bangladesh.Study uncovered many new amino acid substitutions as well as a predominance of single haplotype in Indian subcontinent except in north-eastern region of the country.The amino acid substitutions data generated in this study from different geographical regions of the Indian subcontinent could be helpful in designing a more effective anti-malarial transmission-blocking vaccine.

View Article: PubMed Central - HTML - PubMed

Affiliation: Genetics and Molecular Biology Laboratory, National Institute of Malaria Research, Sector-8, Dwarka, New Delhi 110077, India.

ABSTRACT

Background: Genetic polymorphism is an inevitable component of a multistage infectious organism, such as the malaria parasite. By means of genetic polymorphism, parasite opts particular polymorph and reveals survival advantage. Pvs25 and pvs28 are sexual stage antigen genes, expressed at the ookinete stage inside the mosquito gut, and considered as potential transmission-blocking vaccine candidates. This study presents sequence variations in two important transmission blocking antigen genes pvs25 and pvs28 in the field isolates of P. vivax from the Indian subcontinent.

Methods: One hundred microscopically diagnosed P. vivax isolates were collected from five geographical regions of India. Pvs25 and pvs28 genes were PCR amplified and sequenced to assess sequence variation among field isolates.

Results: A total of 26 amino acid substitutions were observed in Pvs25 (10) and Pvs28 (16) among field isolates of P. vivax. Tandem repeat polymorphism observed in pvs28 shows 3-6 tandem repeats in the field isolates. Seven and eight novel amino acid substitutions were observed in Pvs25 and Pvs28, respectively in Indian isolates. Comparison of amino acid substitutions suggests that majority of substitutions observed in global isolates were also present in Indian subcontinent. A single haplotype was observed to be major haplotype among isolates of Delhi, Nadiad, Chennai and Panna except in isolates of Kamrup. Further, population comparison analyses suggest that P. vivax isolates inhabiting in north-eastern region (Kamrup) were distantly related with the isolates from remaining parts of the country. Majority of the amino acid substitutions observed in Indian isolates were more identical to the substitutions reported from isolates of Thailand and Bangladesh.

Conclusion: Study uncovered many new amino acid substitutions as well as a predominance of single haplotype in Indian subcontinent except in north-eastern region of the country. The amino acid substitutions data generated in this study from different geographical regions of the Indian subcontinent could be helpful in designing a more effective anti-malarial transmission-blocking vaccine.

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Related in: MedlinePlus

Genetic differentiation between geographical regions of Indian subcontinent. Red line colour indicates Fst with significant p value (p < 0.001) between populations. Black line indicates Fst with non-significant p value (p > 0.05) between populations. Values in black and blue colours represent Fst estimated at pvs25 and pvs28 respectively.
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Figure 1: Genetic differentiation between geographical regions of Indian subcontinent. Red line colour indicates Fst with significant p value (p < 0.001) between populations. Black line indicates Fst with non-significant p value (p > 0.05) between populations. Values in black and blue colours represent Fst estimated at pvs25 and pvs28 respectively.

Mentions: Haplotyping using DNA sequence polymorphism revealed 10 and 15 haplotypes in pvs25 and pvs28, respectively. Haplotype frequency distribution revealed a single major haplotype at pvs25 (Hap1) and pvs28 (Hap8) among five geographical regions of the Indian subcontinent (Table 4). Highest number of haplotypes was observed in isolates of Kamrup (north-eastern region). All though, few haplotypes observed in relatively low frequency at pvs25 (9) and pvs28 (14) were specific to a particular population. Pair-wise comparison using Fst difference between populations is presented in Figure 1. The pair-wise Fst difference on the basis of both pvs25 and pvs28 haplotypes, revealed that all studied populations significantly differ with Kamrup population (north-eastern region) with a non-significant differentiation among the four regions (Panna, Delhi, Nadiad, and Chennai) (Figure 1). The FST values showed existence of significant level of gene flow among isolates of Chennai, Delhi, Panna, and Nadiad regions.


Antigenic repertoire of Plasmodium vivax transmission-blocking vaccine candidates from the Indian subcontinent.

Prajapati SK, Joshi H, Dua VK - Malar. J. (2011)

Genetic differentiation between geographical regions of Indian subcontinent. Red line colour indicates Fst with significant p value (p < 0.001) between populations. Black line indicates Fst with non-significant p value (p > 0.05) between populations. Values in black and blue colours represent Fst estimated at pvs25 and pvs28 respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3104378&req=5

Figure 1: Genetic differentiation between geographical regions of Indian subcontinent. Red line colour indicates Fst with significant p value (p < 0.001) between populations. Black line indicates Fst with non-significant p value (p > 0.05) between populations. Values in black and blue colours represent Fst estimated at pvs25 and pvs28 respectively.
Mentions: Haplotyping using DNA sequence polymorphism revealed 10 and 15 haplotypes in pvs25 and pvs28, respectively. Haplotype frequency distribution revealed a single major haplotype at pvs25 (Hap1) and pvs28 (Hap8) among five geographical regions of the Indian subcontinent (Table 4). Highest number of haplotypes was observed in isolates of Kamrup (north-eastern region). All though, few haplotypes observed in relatively low frequency at pvs25 (9) and pvs28 (14) were specific to a particular population. Pair-wise comparison using Fst difference between populations is presented in Figure 1. The pair-wise Fst difference on the basis of both pvs25 and pvs28 haplotypes, revealed that all studied populations significantly differ with Kamrup population (north-eastern region) with a non-significant differentiation among the four regions (Panna, Delhi, Nadiad, and Chennai) (Figure 1). The FST values showed existence of significant level of gene flow among isolates of Chennai, Delhi, Panna, and Nadiad regions.

Bottom Line: Majority of the amino acid substitutions observed in Indian isolates were more identical to the substitutions reported from isolates of Thailand and Bangladesh.Study uncovered many new amino acid substitutions as well as a predominance of single haplotype in Indian subcontinent except in north-eastern region of the country.The amino acid substitutions data generated in this study from different geographical regions of the Indian subcontinent could be helpful in designing a more effective anti-malarial transmission-blocking vaccine.

View Article: PubMed Central - HTML - PubMed

Affiliation: Genetics and Molecular Biology Laboratory, National Institute of Malaria Research, Sector-8, Dwarka, New Delhi 110077, India.

ABSTRACT

Background: Genetic polymorphism is an inevitable component of a multistage infectious organism, such as the malaria parasite. By means of genetic polymorphism, parasite opts particular polymorph and reveals survival advantage. Pvs25 and pvs28 are sexual stage antigen genes, expressed at the ookinete stage inside the mosquito gut, and considered as potential transmission-blocking vaccine candidates. This study presents sequence variations in two important transmission blocking antigen genes pvs25 and pvs28 in the field isolates of P. vivax from the Indian subcontinent.

Methods: One hundred microscopically diagnosed P. vivax isolates were collected from five geographical regions of India. Pvs25 and pvs28 genes were PCR amplified and sequenced to assess sequence variation among field isolates.

Results: A total of 26 amino acid substitutions were observed in Pvs25 (10) and Pvs28 (16) among field isolates of P. vivax. Tandem repeat polymorphism observed in pvs28 shows 3-6 tandem repeats in the field isolates. Seven and eight novel amino acid substitutions were observed in Pvs25 and Pvs28, respectively in Indian isolates. Comparison of amino acid substitutions suggests that majority of substitutions observed in global isolates were also present in Indian subcontinent. A single haplotype was observed to be major haplotype among isolates of Delhi, Nadiad, Chennai and Panna except in isolates of Kamrup. Further, population comparison analyses suggest that P. vivax isolates inhabiting in north-eastern region (Kamrup) were distantly related with the isolates from remaining parts of the country. Majority of the amino acid substitutions observed in Indian isolates were more identical to the substitutions reported from isolates of Thailand and Bangladesh.

Conclusion: Study uncovered many new amino acid substitutions as well as a predominance of single haplotype in Indian subcontinent except in north-eastern region of the country. The amino acid substitutions data generated in this study from different geographical regions of the Indian subcontinent could be helpful in designing a more effective anti-malarial transmission-blocking vaccine.

Show MeSH
Related in: MedlinePlus