|
Memórias do Instituto Oswaldo Cruz
Fundação Oswaldo Cruz, Fiocruz
ISSN: 1678-8060 EISSN: 1678-8060
Vol. 90, Num. 4, 1995, pp. 511-512
|
Mem Inst Oswaldo Cruz, Rio de Janeiro, Vol.
90(4): 511-512 Jul/Aug. 1995
RESEARCH NOTE
Prevalence of Antibodies to Potential Malaria Vaccine Antigens
in an Endemic Area of the State of Rondonia (Brazil)
Helena Cristina Balthazar-Guedes, Maria de Fatima
Ferreira-da-Cruz, Claudio Tadeu Daniel-Ribeiro+
Departamento de Imunologia, Instituto Oswaldo Cruz, Av. Brasil
4365, 21045-900 Rio de Janeiro, RJ, Brasil
Code Number: OC95100
Size of Files:
Text: 9K
No associated graphics
Key words: malaria - Plasmodium falciparum - vaccine
Two of the most promising Plasmodium falciparum blood
stage antigens to be included in a malaria vaccine are the
gp190 and the Pf155/RESA, since these antigens are able to
induce the production of antibodies with protective effects
and their presence are related to the degree of immunity (LH
Perrin, R Dayal 1982 Immunol Rev 61: 245-269, P Deloron et
al. 1987 Am J Trop Med Hyg 37: 22-26).
Seroepidemiological studies using gp190 and Pf155/RESA have
been conducted mainly in Africa (HM Muller et al. 1989
Infect Immun 57: 3765-3769, R Tolle et al. 1993 Infect
Immun 61: 40-47, Deloron loc.cit., C Chizzolini et al.
1989 Trans R Soc Trop Med Hyg 83: 147-151) and in Brazil there
has so far been little research concerning the antibody
response of P. falciparum malaria to these peptides (RS
Malafronte et al. 1994 Rev Inst Med Trop S Paulo 36:
369-371).
We have recently conducted a survey in the municipality of
Ariquemes (State of Rondonia, Brazil) with the main objective
of establishing immunological criteria for the recognition of
acute malaria infection. By studying the immune response
against P. falciparum antigens we could identify a 40 kDa
component associated to active disease (HC Balthazar-Guedes
et al. Parasitol Res in press). This study enabled us
also to analyze the pattern of antibody response to some of
the previously described antigens in the migrant population of
Ariquemes.
As the knowledge of the immune response to these polypeptides
in different populations is pertinent to evaluate the
potential use of the gp190 and Pf155/RESA polypeptides for
subunit malaria vaccine, we report here the data concerning a
sample of the Brazilian population.
The population studied, comprised mainly young migrants (x=30
years) living for nearly five years in the endemic region. The
2486 Brazilian isolate of P. falciparum, maintained
asynchronously in vitro, was used as source of antigen
(W Trager, J Jensen 1976 Science 193: 673-675). The components
of the parasite were fractionated by SDS-PAGE on a
discontinuous SDS buffer system 7% to 10% (VK Laemmli 1970
Nature 227: 680-685) adapted for slabs (FW Studier 1973 J Mol
Biol 79: 237-248), associated to the immunoblotting technique
(HU Towbin et al. 1979 Proc Natl Acad Sci USA 76:
4350-4354). In order to perform all the immunoblots in
strictly comparable conditions, an improved immunoblotting
system was utilized (J Thelu et al. 1991 J Clin
Microbiol 29: 510-518). Using this technique, we analyzed a
total of 76 individuals. Twenty five of them were
primeinfected (14 with positive and 11 with negative thick
blood smear [TBS] ) and 51 were polyinfected (median=10.2 past
attacks of malaria) subjects (26 with positive and 25 with
negative TBS).
The mean time elapsed after the last malaria attack referred
by individuals with negative TBS was 48 months in
primeinfected and 12 months among polyinfected subjects.
Several polypeptides distributed between 190 and 10 kDa were
recognized by most of the IgG antibodies present in the serum
of prime and polyinfected individuals. Among them, the
polypeptides of 190 and 155 kDa, were the most frequently
recognized (66% and 24%, respectively).
As expected, polyinfected individuals showed the highest
percentage of reactivity against both polypeptides. The
polypeptide of 190 kDa was recognized by all the 26
parasitized polyinfected individuals regardless the number of
past attacks of malaria and by 7 out of 14 (50%) of
primeinfected with positive thick blood smear. Similar
percentages were observed in 5 out of 11 prime and 12 out of
25 polyinfected subjects with negative TBS (45% and 48%,
respectively) (Table I). These differences were also apparent
when we compared only prime and polyinfected subjects having
had the last malaria attack less than one year before
examination (Table II).
Only polyinfected individuals were able to recognize the
component of 155 kDa. The prevalence of IgG antibodies against
this polypeptide was higher among the 26 parasitized
polyinfected individuals (46%) than in non parasitized ones
(24%) (Table I), stressing the importance of boosting to the
appearance of the immune response directed to the 155 kDa
component.
Table I. Percentage recognition of gp190 and Pf155/RESA
Plasmodium falciparum polpeptides by the IgG present in
sera from all prime and polyinfected individuals studied.
------------------------------------------------------------
Primeinfected Polyinfected
----------------- -----------------
TBS TBS
Polypeptide ----------------- -----------------
Pos Neg Pos Neg
(np/n) (np/n) (np/n) (np/n) Total
-------------------------------------------------------------
gp190 7/14 5/11 26/26 12/25 50/76
(%) (50%) (45%) (100%) (48%) (66%)
Pf155/RESA 0/14 0/11 12/26 6/25 18/76
(%) (0%) (0%) (46%) (24%) (24%)
-------------------------------------------------------------
TBS: thick blood smear; Pos: positive; Neg: negative; np:
number of positive; n: number of individuals
Table II. Percentage recognition of gp190 and Pf155/RESA
Plasmodium falciparum polpeptides by the IgG present in
sera from all prime and polyinfected individuals having had
the last malaria attack in a period =12 months.
------------------------------------------------------
Primeinfected Polyinfected
----------------- -----------------
TBS TBS
Polypeptide ----------------- -----------------
Pos Neg Pos Neg
(np/n) (np/n) (np/n) (np/n)
------------------------------------------------------
gp190 7/14 1/4 26/26 10/19
(%) (50%) (7%) (100%) (53%)
Pf155/RESA 0/14 0/4 12/26 5/19
(%) (0%) (0%) (46%) (26%)
-------------------------------------------------------
TBS: thick blood smear; Pos: positive; Neg: negative; np:
number of positive; n: number of individuals
Previous studies suggest that the anti-Pf155 and the
anti-gp190 antibodies are involved in controlling parasitemia
or providing protection against clinical malaria (Chizzolini
loc. cit., Tolle loc.cit.). In our study the parasite rates in
infected subjects with no antibodies to these antigens were
similar to those recorded in subjects having such antibodies.
These data could reflect the short time of exposure and the
low grade of immunity of these individuals. In fact, this
population comprises migrant individuals and it is well known
that high levels of antibody to the polypeptides in human
primed by natural infection require repeated infections for
full expression (H Perlmann et al. 1984 J Exptl Med
159: 1686-1704, Deloron loc.cit., Tolle loc.cit.). Together
with previously reported results, the present data suggest
that the population studied here must probably be considered a
priority target for immunoprophylactic campaigns in the
future. The existence of baseline data concerning the immune
status of different populations in the Amazon basin could help
in the evaluation of the impact of implementation of malaria
control measures.
Acknowledgements: to Drs Romeu Rodrigues Fialho and Sandra
Ferraciolli, Fundacao Nacional de Saude for logistical support
during the field studies.
Copyright 1995 Fundacao Oswaldo Cruz
|