Characteristic Age Distribution of Plasmodium vivax Infections after Malaria Elimination on Aneityum Island, Vanuatu

ABSTRACTResurgence is a major concern after malaria elimination. After the initiation of the elimination program on Aneityum Island in 1991, microscopy showed thatPlasmodium falciparumdisappeared immediately, whereasP. vivaxdisappeared from 1996 onward, untilP. vivaxcases were reported in January 2002. By conducting malariometric surveys of the entire population of Aneityum, we investigated the age distribution of individuals with parasites during this epidemic in the context of antimalarial antibody levels and parasite antigen diversity. In July 2002,P. vivaxinfections were detected by microscopy in 22/759 individuals: 20/298 born after the beginning of the elimination program in 1991, 2/126 born between 1982 and 1991, and none of 335 born before 1982. PCR increased the number of infections detected to 77, distributed among all age groups. Prevalences were 12.1%, 16.7%, and 6.0%, respectively (P< 0.001). In November, a similar age pattern was found, but with fewer infections: 6/746 and 39/741 individuals were found to be infected by microscopy and PCR, respectively. The frequencies of antibody responses toP. vivaxwere significantly higher in individuals born before 1991 than in younger age groups and were similar to those on Malakula Island, an area of endemicity. Remarkably low antigen diversity (h, 0.15) ofP. vivaxinfections was observed on Aneityum compared with the other islands (h, 0.89 to 1.0). AP. vivaxresurgence was observed among children and teenagers on Aneityum, an age distribution similar to those before elimination and on islands whereP. vivaxis endemic, suggesting that in the absence of significant exposure, immunity may persist, limiting infection levels in adults. The limited parasite gene pool on islands may contribute to this protection.

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Plasmodium falciparum Gametocyte-Specific Antibody Profiling Reveals Boosting through Natural Infection and Identifies Potential Markers of Gametocyte Exposure

Infection and Immunity ◽

10.1128/iai.00644-15 ◽

2015 ◽

Vol 83 (11) ◽

pp. 4229-4236 ◽

Cited By ~ 15

Author(s):

Jeff Skinner ◽

Chiung-Yu Huang ◽

Michael Waisberg ◽

Philip L. Felgner ◽

Ogobara K. Doumbo ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Specific Antibody ◽

Malaria Elimination ◽

Natural Infection ◽

Antibody Responses ◽

Clear Understanding ◽

Content Type ◽

Block Transmission ◽

Proteomic Data ◽

Before And After

ABSTRACTMalaria elimination efforts would benefit from vaccines that block transmission ofPlasmodium falciparumgametocytes from humans to mosquitoes. A clear understanding of gametocyte-specific antibody responses in exposed populations could help determine whether transmission-blocking vaccines (TBV) would be boosted by natural gametocyte exposure, and also inform the development of serologic tools to monitor gametocyte exposure in populations targeted for malaria elimination. To this end, plasma was collected from Malian children and adults before and after the 6-month malaria season and probed against a microarray containing 1,204P. falciparumproteins. Using publicly available proteomic data, we classified 91 proteins as gametocyte specific and 69 as proteins not expressed by gametocytes. The overall breadth and magnitude of gametocyte-specific IgG responses increased during the malaria season, although they were consistently lower than IgG responses to nongametocyte antigens. Notably, IgG specific for the TBV candidates Pfs48/45 and Pfs230 increased during the malaria season. In addition, IgGs specific for the gametocyte proteins Pfmdv1, Pfs16, PF3D7_1346400, and PF3D7_1024800 were detected in nearly all subjects, suggesting that seroconversion to these proteins may be a sensitive indicator of gametocyte exposure, although further studies are needed to determine the specificity and kinetics of these potential serologic markers. These findings suggest that TBV-induced immunity would be boosted through natural gametocyte exposure, and that antibody responses to particular antigens may reliably indicate gametocyte exposure.

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Allele Specificity of Naturally Acquired Antibody Responses against Plasmodium falciparum Apical Membrane Antigen 1

Infection and Immunity ◽

10.1128/iai.73.1.422-430.2005 ◽

2005 ◽

Vol 73 (1) ◽

pp. 422-430 ◽

Cited By ~ 52

Author(s):

Alfred Cortés ◽

Mata Mellombo ◽

Rosella Masciantonio ◽

Vince J. Murphy ◽

John C. Reeder ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Apical Membrane ◽

Age Groups ◽

Antibody Responses ◽

Allelic Form ◽

Apical Membrane Antigen 1 ◽

Apical Membrane Antigen ◽

Younger Age ◽

Merozoite Antigens ◽

Allele Specificity

ABSTRACT Antibody responses against proteins located on the surface or in the apical organelles of merozoites are presumed to be important components of naturally acquired protective immune responses against the malaria parasite Plasmodium falciparum. However, many merozoite antigens are highly polymorphic, and antibodies induced against one particular allelic form might not be effective in controlling growth of parasites expressing alternative forms. The apical membrane antigen 1 (AMA1) is a polymorphic merozoite protein that is a target of naturally acquired invasion-inhibitory antibodies and is a leading asexual-stage vaccine candidate. We characterized the antibody responses against AMA1 in 262 individuals from Papua New Guinea exposed to malaria by using different allelic forms of the full AMA1 ectodomain and some individual subdomains. The majority of individuals had very high levels of antibodies against AMA1. The prevalence and titer of these antibodies increased with age. Although antibodies against conserved regions of the molecule were predominant in the majority of individuals, most plasma samples also contained antibodies directed against polymorphic regions of the antigen. In a few individuals, predominantly from younger age groups, the majority of antibodies against AMA1 were directed against polymorphic epitopes. The D10 allelic form of AMA1 apparently contains most if not all of the epitopes present in the other allelic forms tested, which might argue for its inclusion in future AMA1-based vaccines to be tested. Some important epitopes in AMA1 involved residues located in domain II or III but depended on more than one domain.

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Molecular characterization of Plasmodium falciparum PHISTb proteins as potential targets of naturally-acquired immunity against malaria

Wellcome Open Research ◽

10.12688/wellcomeopenres.15919.1 ◽

2020 ◽

Vol 5 ◽

pp. 136

Author(s):

Tony I. Isebe ◽

Joel L. Bargul ◽

Bonface M. Gichuki ◽

James M. Njunge ◽

James Tuju ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Malaria Transmission ◽

The Gambia ◽

Antibody Responses ◽

Transmission Intensity ◽

Parasite Development ◽

Natural Immunity ◽

Malaria Transmission Intensity ◽

Transmission Region ◽

Antibody Levels

Background: Plasmodium falciparum causes the deadliest form of malaria in humans. Upon infection, the host’s infected red blood cells (iRBCs) are remodelled by exported parasite proteins in order to provide a niche for parasite development and maturation. Methods: Here we analysed the role of three PHISTb proteins Pf3D7_0532400, Pf3D7_1401600, and Pf3D7_1102500 by expressing recombinant proteins and evaluated antibody responses against these proteins using immune sera from malaria-exposed individuals from Kenya and The Gambia in Africa. Results: Our findings show that children and adults from malaria-endemic regions recognized the three PHISTb proteins. Responses against the PHISTb proteins varied with malaria transmission intensity in three different geographical sites in Kenya (Siaya and Takaungu) and The Gambia (Sukuta). Antibody responses against PHISTb antigens Pf3D7_1102500 and Pf3D7_1401600 were higher in Sukuta, a low transmission region in the Gambia, as compared to Siaya, a high transmission region in western Kenya, unlike Pf3D7_0532400. Anti-PHIST responses show a negative correlation between antibody levels and malaria transmission intensity for two PHIST antigens, Pf3D7_1102500 and Pf3D7_1401600. However, we report a correlation in antibody responses between schizont extract and Pf3D7_0532400 (p=0.00582). Acquisition of anti-PHIST antibodies was correlated with exposure to malaria for PHISTb protein Pf3D7_0532400 (p=0.009) but not the other PHIST antigens Pf3D7_1102500 and Pf3D7_1401600 (p=0.507 and p=0.15, respectively, CI=95%). Children aged below 2 years had the lowest antibody levels, but the responses do not correlate with age differences. Conclusions: Collectively, these findings provide evidence of natural immunity against PHISTb antigens that varies with level of malaria exposure and underscore potential for these parasite antigens as possible serological markers to P. falciparum infection aimed at contributing to malaria control through vaccine development.

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Request Strategies in the American TV Series Full House

Lexicon ◽

10.22146/lexicon.v6i1.50308 ◽

2019 ◽

Vol 6 (1) ◽

Author(s):

Yemima Febriani ◽

Sharifah Hanidar

Keyword(s):

Social Distance ◽

Family Members ◽

Age Groups ◽

The Other ◽

Relative Power ◽

Adult Age ◽

Other Hand ◽

Younger Age ◽

The Social ◽

Request Strategies

This research aims to analyze the request strategies used in an American TV Series entitled Full House season 7 episodes 1-12. The main characters are family members from three different age groups (adult, teenager, and children). This research attempts to see if there is any difference on the choice of request strategies used by the three age groups. Blum-Kulka and Olshtain’s (1984) theory on request directness level is used to classify the requests. Relative power and social distance are also studied to see how they influence the characters in making their requests. The results show that mood derivable is the most frequent strategy used by all age groups. Specifically, direct request is highly used by the adult age groups. On the other hand, indirect request is mostly used by the younger age groups. The results also show that all age groups tend to use direct strategy when the social distance is negative. However, when the social distance is positive, the choice of strategy depends on the authority of the speaker.

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Preliminary analysis on food intolerances of 88,436 healthy people to 14 kinds of foods

British Food Journal ◽

10.1108/bfj-07-2018-0482 ◽

2019 ◽

Vol 121 (5) ◽

pp. 1010-1019 ◽

Cited By ~ 1

Author(s):

Yansong Zheng ◽

Liping Zhang ◽

Qiang Zeng ◽

Chaojin Han

Keyword(s):

Age Groups ◽

Healthy People ◽

Healthy Foods ◽

Content Type ◽

The People ◽

Younger Age ◽

Significant Difference ◽

Positive Rate ◽

Specific Igg ◽

Specific Igg Antibodies

PurposeFunctional disorders caused by food intolerance (FI) are prevalent, thus it is important to analyze the FI of healthy people to common foods so as to guide the people for eating the healthy foods. The paper aims to discuss this issue.Design/methodology/approachIn total, 88,436 healthy persons including 60,902 males and 27,534 females at the age ranging from 20 to 70 years old were subjected a normal physical examination. In total, 14 kinds of food-specific IgG antibodies were detected by enzyme-linked immunesorbent assay.FindingsThe total positive rate of 14 FIs was as high as 64.16 percent. Five kinds of foods (egg, crab, cod, shrimp and milk) accounted for 84.51 percent of the total positive rate. In more than one kind of FIs, egg took the largest proportion than the others and the proportion was 58.54 percent. The second was crab with a positive rate of 56.19 percent. The antibody positive rate of any food in one kind of FIs was significantly lower than that in more than one kind of FIs (χ2=629.35,p<0.001). Also, younger age subjects displayed the higher positive rate than the older age groups. In addition, there was no significant difference on FI between male and female subjects.Originality/valueThe results would not only prompt us to pay more attention to FI in daily life, but provide theoretical foundation for the early prevention, diagnosis and treatment of related clinical diseases as well as guiding people healthy meals.

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Haemagglutination-inhibiting (HI) antibodies against four prototype strains of influenza A virus in different age groups

Journal of Hygiene ◽

10.1017/s0022172400025638 ◽

1979 ◽

Vol 82 (2) ◽

pp. 225-230 ◽

Cited By ~ 1

Author(s):

A. L. Terzin ◽

S. Djurišić ◽

B. Vuković ◽

V. Vujkov

Keyword(s):

Influenza Virus ◽

Hong Kong ◽

New Jersey ◽

Antibody Response ◽

Influenza A ◽

Geometric Mean ◽

Age Groups ◽

The Other ◽

Younger Age ◽

Lower Antibody Response

SUMMARYSera of 197 apparently well persons were tested for residual haemagglutination-inhibiting antibodies against live Hong Kong/68, A/FM/47 and A/PR/34 strains. Sera of 62 well persons, regularly exposed to contacts with swine, were tested against an inactivated A/New Jersey/76 antigen.Those born some time before and during a certain influenza era showed a significantly greater proportion of homologous residual titres against the subtype prevailing in that influenza era, than those born after the termination of the same era.In each of the seven age groups tested both the percentage of positives and the geometric mean titres were usually highest against the Hong Kong strain (representing the most recent era); the next highest were those against the FM1 strain and the lowest were those against the PR8 strain (representing the most distant of these three influenza eras).The serological involvement of donors exposed to regular contacts with swine was relatively stronger against the New Jersey antigen than the response of other serum donors shown against the other three, more recent, prototypes of influenza virus A. The oldest age groups showed significantly lower antibody response against the PR8, FM1 and Hong Kong strains (but not against the New Jersey antigen) than the next one or two of the younger age groups.

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Antibodies to Borrelia burgdorferi OspA, OspC, OspF, and C6 Antigens as Markers for Early and Late Infection in Dogs

Clinical and Vaccine Immunology ◽

10.1128/cvi.05653-11 ◽

2012 ◽

Vol 19 (4) ◽

pp. 527-535 ◽

Cited By ~ 32

Author(s):

Bettina Wagner ◽

Heather Freer ◽

Alicia Rollins ◽

David Garcia-Tapia ◽

Hollis N. Erb ◽

...

Keyword(s):

Lyme Disease ◽

Borrelia Burgdorferi ◽

The United States ◽

Sensu Stricto ◽

Antibody Responses ◽

Surface Proteins ◽

Early Infection ◽

Enzyme Linked Immunosorbent Assay ◽

Content Type ◽

Antibody Levels

ABSTRACTLyme disease in the United States is caused byBorrelia burgdorferisensu stricto, which is transmitted to mammals by infected ticks.Borreliaspirochetes differentially express immunogenic outer surface proteins (Osp). Our aim was to evaluate antibody responses to Osp antigens to aid the diagnosis of early infection and the management of Lyme disease. We analyzed antibody responses during the first 3 months after the experimental infection of dogs using a novel multiplex assay. Results were compared to those obtained with two commercial assays detecting C6 antigen. Multiplex analysis identified antibodies to OspC and C6 as early as 3 weeks postinfection (p.i.) and those to OspF by 5 weeks p.i. Antibodies to C6 and OspF increased throughout the study, while antibodies to OspC peaked between 7 and 11 weeks p.i. and declined thereafter. A short-term antibody response to OspA was observed in 3/8 experimentally infected dogs on day 21 p.i. Quant C6 enzyme-linked immunosorbent assay (ELISA) results matched multiplex results during the first 7 weeks p.i.; however, antibody levels subsequently declined by up to 29%. Immune responses then were analyzed in sera from 125 client-owned dogs and revealed high agreement between antibodies to OspF and C6 as robust markers for infection. Results from canine patient sera supported that OspC is an early infection marker and antibodies to OspC decline over time. The onset and decline of antibody responses toB. burgdorferiOsp antigens and C6 reflect their differential expression during infection. They provide valuable tools to determine the stage of infection, treatment outcomes, and vaccination status in dogs.

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Molecular characterization of Plasmodium falciparum PHISTb proteins as potential targets of naturally-acquired immunity against malaria

Wellcome Open Research ◽

10.12688/wellcomeopenres.15919.2 ◽

2021 ◽

Vol 5 ◽

pp. 136

Author(s):

Tony I. Isebe ◽

Joel L. Bargul ◽

Bonface M. Gichuki ◽

James M. Njunge ◽

James Tuju ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Malaria Transmission ◽

Negative Correlation ◽

The Gambia ◽

Antibody Responses ◽

Transmission Intensity ◽

Parasite Development ◽

Malaria Transmission Intensity ◽

Transmission Region ◽

Antibody Levels

Background: Plasmodium falciparum causes the deadliest form of malaria in humans. Upon infection, the host’s infected red blood cells (iRBCs) are remodelled by exported parasite proteins to provide a niche for parasite development and maturation. Methods: Here we analysed the role of three PHISTb proteins Pf3D7_0532400, Pf3D7_1401600, and Pf3D7_1102500 by expressing recombinant proteins and evaluated antibody responses against these proteins using immune sera from malaria-exposed individuals from Kenya and The Gambia in Africa. Results: Children and adults from malaria-endemic regions recognized the three PHISTb proteins. Responses against PHISTb proteins varied with malaria transmission intensity in three different geographical sites in Kenya (Siaya and Takaungu) and The Gambia (Sukuta). Antibody responses against PHISTb antigens Pf3D7_1102500 and Pf3D7_1401600 were higher in Sukuta, a low transmission region in Gambia, compared to Siaya, a high transmission region in western Kenya, unlike Pf3D7_0532400. Anti-PHIST responses indicate negative correlation between antibody levels and malaria transmission intensity for Pf3D7_1102500 and Pf3D7_1401600. We report a correlation in antibody responses between schizont and gametocyte extract, but this is not statistically significant (cor=0.102, p=0.2851, CI=95%) and, Pf3D7_0532400 (cor=0.11, p=0.249, CI=95%) and Pf3D7_1401600 (cor=0.02, p=0.7968, CI=95%). We report a negative correlation in antibody responses between schizont and Pf3D7_1102500 (cor=-0.008, p=0.9348, CI=95%). There is a correlation between gametocyte extract and Pf3D7_1401600 (cor=-0.0402, p=0.6735, CI=95%), Pf3D7_1102500 (cor=0.0758, p=0.4271, CI=95%) and Pf3D7_0532400 (cor=0.155, p=0.1028, CI=95%). Acquisition of anti-PHIST antibodies correlates with exposure to malaria for Pf3D7_0532400 (p=0.009) but not Pf3D7_1102500 and Pf3D7_1401600 (p=0.507 and p=0.15, respectively, CI=95%). Children aged below 2 years had the lowest antibody levels which do not correlate with age differences. Conclusions: Collectively, these findings provide evidence of natural immunity against PHISTb antigens that varies with level of malaria exposure and underscore their potential as possible serological markers to P. falciparum infection aimed at contributing to malaria control through vaccine development.

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TBE Vaccination Breakthrough Cases—Does Age Matter?

Vaccines ◽

10.3390/vaccines9080932 ◽

2021 ◽

Vol 9 (8) ◽

pp. 932

Author(s):

Heinz-J. Schmitt ◽

Gerhard Dobler ◽

Dace Zavadska ◽

Zane Freimane ◽

Dimitrios Fousteris ◽

...

Keyword(s):

Age Distribution ◽

Age Groups ◽

The Other ◽

Vaccine Uptake ◽

Priming Dose ◽

Southern Germany ◽

Diagnostic Practices ◽

Tick Borne Encephalitis ◽

Vaccine Failures ◽

Scientific Rationale

Tick-borne encephalitis (TBE) vaccines are highly effective in preventing TBE and vaccine failures (VF) are rare events. In this study, we compared the age distribution of TBE cases and TBE VF in three endemic countries: Sweden, Southern Germany, and Latvia. While the age distribution of TBE cases was similar for those <50 years versus those ≥50 years in all three countries, in Sweden, a higher proportion of VF cases was ≥50 years, whereas most VF cases in Latvia were <50 years of age and more evenly distributed between those <50 years versus those ≥50 in Southern Germany. Here, theoretical explanations were provided, including differences in diagnostic practices, vaccine uptake between age groups, behavioral patterns and underlying medical conditions, as to why VF were generally older in Sweden than the other countries. There is no scientific rationale to give an extra priming dose of TBE vaccine to subjects ≥50 years of age.

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Imported cases, community action, policy and institutional systems drive Hong Kong’s COVID-19 experience

10.31235/osf.io/5zuv7 ◽

2020 ◽

Author(s):

Christian Joy P. Cruz ◽

Rachel Ganly ◽

Zilin Li ◽

Stuart Gietel-Basten

Keyword(s):

Hong Kong ◽

Age Structure ◽

Age Distribution ◽

Age Groups ◽

Health Department ◽

Community Action ◽

Younger Age ◽

Imported Cases ◽

City State ◽

The City

This paper investigates the profile of COVID-19 cases in Hong Kong, highlighting the unique age structure of confirmed cases compared to other states. Whilst the majority of cases in most states around the world have fitted an older age profile, our analysis shows that positive cases in Hong Kong have been concentrated amongst younger age groups, with the largest incidence of cases reported in the 15-24 age group. This is despite the population’s rapidly ageing structure and extremely high levels of population density. Using detailed case data from Hong Kong’s Centre for Health Department and Immigration Department, we analyze the sex and age distribution of the confirmed cases along with their recent travel histories and immigration flows for the period January to April, 2020. Our analysis highlights Hong Kong’s high proportion of imported cases and large overseas student population in developing COVID-19 hotspot areas such as the United Kingdom. Combined with targeted and aggressive early policy measures taken to contain the virus, these factors may have contributed to the uniquely younger age structure of COVID-19 cases in the city. Consequently, this young profile of confirmed cases may have prevented fatalities in the city-state.

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