Protective immunity in bancroftian filariasis. Selective recognition of a 43-kD larval stage antigen by infection-free individuals in an endemic area.

Abstract

There is little information about naturally occurring protective immunity in individuals living in areas endemic for lymphatic filariasis, though an immunologically hyperresponsive, uninfected group of "endemic normal" individuals that may be immune has been previously recognized. To analyze the nature of the hyperresponsiveness and its potential relation to a state of protective immunity in such individuals, strict clinical, parasitological, and serological criteria were applied to select seven "infection-free" endemic normal individuals (ENs) from a population of 459 persons resident in an area heavily endemic for bancroftian filariasis. Immunoblot analysis was used to compare the qualitative antigen recognition patterns of these endemic normal individuals to those of a group of 12 clearly infected microfilaremic individuals (MFs) from the same endemic area. Though immunoblot analysis using microfilarial and adult stage filarial antigens revealed no distinct differences in antigen recognition patterns between the two groups, when responses to infective larval stage antigens were assessed, 7/7 (100%) of the ENs were found to recognize a 43-kD antigen that was recognized by only 1/12 (8%) of the MFs. These findings are consistent with the concept that recognition of unique larval antigens may induce protective immunity to human filarial parasites and they identify a candidate immunogen for further functional assessment.

Effect of muramyl dipeptide and alum adjuvants on immunization with Filarial multi antigen peptide vaccine in mice model

“…Vaccination against parasites is still not a reality, despite decades of research. Strategies to identify candidate vaccine antigens against brugian or bancroftian fi lariasis include screening expression libraries with immune sera (Freedman et al, 1989), differential screening of abundantly expressed mRNAs (Gregory et al, 2000) or by the Expressed Sequence Tag (EST) approach (Blaxter et al, 1999). These strategies have facilitated the identifi cation of several potential vaccine candidates offering varying degrees of protection against fi larial infection in animal models (Thirugnanam et al, 2007;Anand et al, 2008;Vanam et al, 2009;Dakshinamoorthy et al, 2013).…”

Cloning and characterization of a potentially protective Chitinase-like Recombinant Antigen from Wuchereria bancrofti

“…In the ,-translated EcoRI-NcoI (715-bp) fragment which present study, antiserum was raised in rabbits against this the coding region for the chitinase gene. As seen 43- elegans and human) DNAs tested under highly earlier (13). However, this finding indicated that we had only a ditions (38).…”

“…As previously described (13), 7 adults (1 man and 6 women) living in Mauke, Cook islands, an area where subperiodic bancroftian filariasis is hyperendemic, were defined as PI (variously referred to as infection free or endemic normal); 12 others (5 men and 7 women) were identified as clearly infected, microfilaremic. All PI individuals were amicrofilaremic on eight membrane filtration evaluations of their blood, had no historical or physical indication of filarial infection, had none of the reactions to administration with diethylcarbamazine that are characteristic of cryptic infection, and had no circulating antigen detectable in their sera (13 (53). The pUC19 subclone pWbN43 was mapped by using various restriction endonucleases, and three restriction deletion subclones were constructed.…”

“…Since it is impossible to determine resistance to reinfection directly, the study of such immunity in human populations has been particularly difficult because of the inability to distinguish between truly immune individuals and those considered concomitantly immune (infected but resistant to reinfection). Taking a more indirect approach, we have previously reported a group of individuals living in an area where W. bancrofti infection is endemic (Mauke, Cook Islands) whom we defined as putatively immune (PI) on the basis of rigorous clinical, parasitological, and serological criteria (13). These individuals were infection free by all available clinical and laboratory standards but demonstrated significantly greater humoral and cellular responsiveness to parasite antigens than did their compatriots with active filarial infection (30,32,33,36,49).…”

“…When immunoblot analysis was used to compare the qualitative antigen recognition patterns between these two groups of individuals, no distinct differences were seen with either the adult or microfilarial antigen extracts of Brugia malayi, a closely related filarial species. However, when the responses to L3 antigens were assessed, 100% of the PI individuals and only 8% of the infected, microfilaremic subjects recognized a 43-kDa larval-stage antigen (13). It was thus of great interest to characterize this 43-kDa L3 antigen because of its potential as a protective immunogen.…”