Prevalence of neutralizing antibodies against poliovirus 1, 2, and 3 in healthcare professionals aged 20-50 years / Prevalência de anticorpos neutralizantes contra poliovírus 1, 2 e 3 em profissionais de saúde de 20 a 50 anos de idade

ABSTRACT Objective: To describe the prevalence of neutralizing antibodies against poliovirus (PV1, PV2, and PV3) in blood samples of healthcare professionals aged 20 to 50 years. Methods: Health professionals who serve children at Darcy Vargas Children's Hospital and the Department of Pediatrics of Irmandade da Santa Casa de São Paulo. The sample size was calculated at 323 participants. The Mantel-Haenszel chi-square was used to verify differences between groups. The neutralization reaction detected human poliovirus antibodies. For susceptible individuals, vaccination with the inactivated+triple acellular polio vaccine was performed, and neutralizing antibodies were re-dosed after one week. Results: 333 professionals were studied - 92.8% were immune to poliovirus 1, 86.5% to poliovirus 2, and 63.3% to poliovirus 3; 37% had titers less than 1:8 for any serotype, 5;1% had titers below 1:8 for all three. Vaccination with inactivated polio vaccine was performed for susceptible participants, and neutralizing antibodies were dosed after one week, showing increased titers for all polioviruses. Conclusions: Despite the detection of a significant percentage of individuals with low poliovirus antibody titer, the challenge with vaccination demonstrated immune response compatible with poliovirus immunity.

RESUMO Objetivo: Descrever a prevalência de anticorpos neutralizantes contra poliovírus (tipos 1, 2 e 3) em amostra de sangue de profissionais de saúde com idade de 20 a 50 anos. Métodos: Profissionais de saúde que atendem crianças do Hospital Infantil Darcy Vargas e do Departamento de Pediatria da Irmandade da Santa Casa de São Paulo. O tamanho da amostra foi de 323 participantes. Os anticorpos contra poliovírus humanos foram detectados pela reação de neutralização. Para os indivíduos suscetíveis, foram administradas vacina para poliomielite inativada+tríplice e nova dosagem de anticorpos neutralizantes após uma semana. Utilizou-se o teste do qui-quadrado de Mantel-Haenszel para verificar as diferenças entre os grupos. Resultados: Foram estudados 333 profissionais - 92,8% eram imunes ao poliovírus 1; 86,5%, ao poliovírus 2; 63,57%, ao poliovírus 3; 37% apresentaram títulos inferiores a 1:8 para qualquer sorotipo; 5,1% tinham títulos abaixo de 1:8 para os três. Após a vacinação dos suscetíveis, houve elevação dos títulos para todos os poliovírus. Conclusões: Apesar da detecção de percentual significativo de indivíduos com baixo título de anticorpos para poliovírus, o desafio da vacinação demonstrou resposta imune robusta compatível.

Poliovirus neutralizing antibody levels among individuals in three regions of Ghana

Introduction: Ghana was declared polio-free in 2015 after the last polio case in 2008. We determined the poliovirus neutralizing antibody levels among individuals to identify possible immunity gaps. Methods: A cross-sectional, hospital-based study was undertaken in Northern, Ashanti and Greater Accra regions of Ghana. Individuals referred for haematology at the teaching hospitals' laboratories were invited to participate in our study. Neutralizing-antibody titers to poliovirus serotypes 1,2 & 3 were assayed by WHO-standards. Antibody titers of ≥8 were considered protective. Bivariate and multivariate analyses were conducted on subject characteristics to assess potential factors for failure to seroconvert. P-values < 0.05 were considered statistically significant. Results: Poliovirus (PV) neutralizing-antibody serotypes 1, 2 and 3 were detected in 86.0% (264/307), 84% (258/307) and 75% (230/307) of samples respectively. 60.1% (185/307) were seropositive for the three poliovirus serotypes. Neutralizing poliovirus antibodies for PV1 and PV2 were higher than for PV3. Seroprevalence of poliovirus-neutralizing antibodies among males (PV1=51.9%, PV2= 51.6% and PV3= 52.6%) were higher than in females. Seroprevalence rates of poliovirus-neutralizing antibodies (PV1, PV2, and PV3) were highest in the Northern region (90%, 81%, and 77%). Poliovirus neutralizing-antibodies (PV1and PV2) decreased with age [p< 0.001]. Low seroprevalence of poliovirus-neutralizing antibodies was significantly associated with low school attendance of mothers (p<0.001). Conclusion: Our study population has some protection from polio. However, immunity appears to be lower with a higher age or low Mother's education. This may suggest the need for young-adult booster-dose to minimize the risk of wild poliovirus infection

La vacuna polio oral en lactantes no interfiere con la detección de enterovirus en sangre / Oral polio vaccine in infants does not interfere in detection of enterovirus in blood

Introduction: There is not known if a viraemia post-oral polio vaccine (OPV) is detectable by modern molecular techniques. Such viraemia could affect the performance of the real time-polymerase chain reaction (PCR) for non polio enterovirus (EV) detection, technique of growing clinical use for the study of febrile infants. Objective: To determine viraemia post-first dose of OPV in healthy infants, by molecular techniques. Patients and Methods: 50 infants less than three months without previous VPO were randomized in 5 groups: a control group with pre-vaccination blood sample (BS), group 1 BS at day 2, group 2 BS at day 4, group 3, BS at day 6 and group 4, BS at day 8 post-vaccination. Conventional and specific PCR for poliovirus and real time PCR for non polio EV were performed in BS and in OPV samples. Results: No genetic material of poliovirus was detected in any infant, while in 9 of them (18%) non polio EV was identified. Real time PCR for EV did not amplify poliovirus from OPV samples. Discussion: Results suggest that no post VPO viraemia detectable by molecular methods exists. Considering that real time PCR for EV does not allow to identify polio virus, no false positives of the test are expected as a result of a recent VPO vaccination. We documented presence of non polio EV in blood of healthy asymptomatic infants.

Introducción: No existen estudios que indiquen si la vacuna polio oral (VPO) produce viremia detectable mediante métodos moleculares. Una eventual viremia podría afectar el rendimiento de la RPC tiempo real para detectar enterovirus (EV) no polio, examen de creciente uso clínico en lactantes pequeños con fiebre sin foco. Objetivo: Determinar viremia post VPO en lactantes sanos, por métodos moleculares. Métodos: 50 menores de 3 meses, al momento de recibir su primera VPO se distribuyeron en forma aleatoria en 5 grupos: control, muestra de sangre pre-vacunación; grupo 1, muestra al 2° día; grupo 2, al 4° día; grupo 3, al 6° día y grupo 4, al 8° día post-vacunación. Se realizó RPC convencional específica para virus polio y RPC tiempo real para EV no polio en las muestras de sangre y en muestras de VPO. Resultados: No se identificó presencia de material genético de virus polio en lactante alguno, mientras que en 9 (18%) se identificó presencia de EV no polio. La RPC tiempo real para EV no polio no amplificó material genético a partir de las muestras de VPO. Discusión: Los resultados sugieren que no existe viremia post-VPO detectable por métodos moleculares. Considerando que la RPC tiempo real de EV no polio de uso clínico no permite identificar la presencia de virus polio, estos hallazgos indican que no existirán falsos positivos de este examen como resultado de una vacunación VPO reciente. Adicionalmente se documentó presencia de EV no polio en sangre de lactantes asintomáticos.

A RT-PCR method for selective amplification and phenotypic characterization of all three serotypes of Sabin-related polioviruses from viral mixtures

Outbreaks caused by vaccine-derived polioviruses are challenging the final eradication of paralytic poliomyelitis. Therefore, the surveillance of the acute flaccid paralysis cases based on poliovirus isolation and characterization remains an essential activity. Due to the use of trivalent oral poliovirus vaccine (OPV), mixtures containing more than one serotype of Sabin-related polioviruses are frequently isolated from clinical samples. Because each poliovirus isolate needs to be individually analyzed, we designed polymerase chain reaction primers that can selectively distinguish and amplify a genomic segment of the three Sabin-related poliovirus serotypes present in mixtures, thus, optimizing the diagnosis and providing prompt information to support epidemiologic actions.

Evaluation of intensive pulse polio immunization in District Valsad during 2007.

Three rounds of pulse polio immunization in January, February and March, 2007 were evaluated in Valsad and Vapi cities. Randomly selected team members of 50% booths and teams working during house to house activity were interviewed. Approximately 80% of eligible children were immunized on booths whereas remaining eligible were covered during house to house activity. In February, 2007 round, mOPV type 1 was first time introduced in Gujarat. Utilizers of booth services received information about these rounds mainly from television and miking. During house to house activity, few unimmunised children were found. Adequate manpower with proper training and community mobilization can improve the coverage.

Seroepidemiology of poliovirus antibody among the children in Eastern Turkey.

BACKGROUND & OBJECTIVE: Data on immunization are generally based on questionnaire methods or evaluation of health records in most of the developing countries like Turkey. Therefore, serological studies are useful to appraise the impact of vaccination programmes and to improve immunization policies. This serological study was undertaken to determine the immunity status of children to poliovirus in Eastern Turkey. METHODS: A cross-sectional and community-based field study was done with the sampling method of 30 clusters recommended for field studies. A total of 204 children aged 2-71 months were included. Complement fixation test was used to measure antibody titres to poliovirus serotypes. Subjects with serum antibody titres as 1:10 and lower were accepted as seronegative. A semi-structured questionnaire and official records of health care units were used to gather information about status of vaccination. RESULTS: Of the 204 children included, 54.4 per cent were boys and mean age was 31.5 +/- 19.8 months; 26.5 per cent of the children were seronegative. According to official records 64.7 per cent of subjects were full vaccinated. Sensitivity and specificity of official health records were 83.6 and 67.3 per cent in relation to immunity status of children, respectively. Regarding number of OPV doses given to children, the sensitivity and specificity of parents recall in relation to official records were 98.0 and 17.4 per cent, respectively. INTERPRETATION & CONCLUSION: Approximately, one of four children was determined to be seronegative. This high seronegativity brings risk to control of polio in Eastern Turkey which is at the post-elimination era since 1998. Additionally, parents recall did not provide reliable information to predict the immunity status and number of OPV doses given to children.

Investigation of circulating anti-coxsackie B, anti- polio and anti-adeno IgG in newly diagnosed T1DM children

Viruses may be involved in the pathogenesis of Type 1 Diabetes Mellitus [T1DM], either through direct beta-cell infection or as triggers of autoimmunity. To investigate the presence of specific anti- viral IgG antibodies for Coxsackie virus type B [CVB5], Poliovirus, and Adenovirus which proposed to be involved in the etiology of T1DM. A total of 60 Iraqi T1DM children were included in the present study. They were new onset of the disease [diagnosis was from one week up to five months]. For the purpose of comparisons, 50 apparently healthy control subjects were selected. Serum IgG against Coxsackie virus type B[5], Adenovirus type 3, 4, and 7, and Poliovaccin Trivalent were detected quantitatively with an indirect ELISA. High proportion of anti-CVB5 IgG [20%][p<0.05] and anti- Polio IgG [31.67%] were found in T1DM children compared to controls [8%, 26% respectively], while anti- Adeno IgG were detected in diabetic patients only [6.67%][p<1.0001]

Recombinant viruses as vaccines against viral diseases

Vaccine approaches to infectious diseases are widely applied and appreciated. Amongst them, vectors based on recombinant viruses have shown great promise and play an important role in the development of new vaccines. Many viruses have been investigated for their ability to express proteins from foreign pathogens and induce specific immunological responses against these antigens in vivo. Generally, gene-based vaccines can stimulate potent humoral and cellular immune responses and viral vectors might be an effective strategy for both the delivery of antigen-encoding genes and the facilitation and enhancement of antigen presentation. In order to be utilized as a vaccine carrier, the ideal viral vector should be safe and enable efficient presentation of required pathogen-specific antigens to the immune system. It should also exhibit low intrinsic immunogenicity to allow for its re-administration in order to boost relevant specific immune responses. Furthermore, the vector system must meet criteria that enable its production on a large-scale basis. Several viral vaccine vectors have thus emerged to date, all of them having relative advantages and limits depending on the proposed application, and thus far none of them have proven to be ideal vaccine carriers. In this review we describe the potential, as well as some of the foreseeable obstacles associated with viral vaccine vectors and their use in preventive medicine.

Antibody levels against polioviruses in children following Pulse Polio Immunization Program.

This cross sectional study was performed in a tertiary level teaching hospital to evaluate and compare the antibody levels in children below 6 years who had received oral polio vaccination through Pulse Polio Immunization (PPI) with those children who had received both routine immunization as well as PPI. Detail history of polio immunization was taken. Serum samples were then collected for antibody determination by neutralization tests with standard polio viruses using Vero cell lines. Total 400 children were studied; 14 were found unvaccinated. Out of the remaining 386 (96.5%) vaccinated children, 292 (75%) had received both routine and pulse polio immunization, 68 (17%) had only PPI while 26 (6.7%) had received only routine immunization. The seropositivity was lowest for P3 and highest for P2. Overall seroprevalence for PI, P2 and P3 in vaccinated children was 89.1%, 93% and 80.6% respectively, and did not differ significantly between the three vaccinated subgroups. However, children who were immunized by both routine and PPI had higher geometric mean titers (315.5, 484.7 and 187.4 for PI, P2 and P3 respectively) when compared with those who had received only PPI (P<0.001 for each PI, P2 and P3), as well as those who had received only routine immunization with OPV (P<0.05 for PI, p<0.001 for P2, and P<0.01 for P3). Despite the reasonable immunization coverage in study population, there were 29 (7.25%) triple negative cases. Hence other causes of low seroconversion should also be considered to achieve polio free India.

Challenges in the final stage of polio eradication.

India and many other countries of the world have supported the resolution taken by the World Health Organization (WHO) in 1988 to eradicate poliomyelitis globally by the year 2000. At the beginning of 2002, there were 10 countries in the world with endemic transmission. India included in the high transmission area. WHO is preparing guidelines on the program response (both immunization and surveillance) to wild poliovirus isolation from the environment. This technology will be useful in monitoring the disappearance of vaccine virus after ceasing OPV vaccination.

Declining trend in routine UIP coverage.

Routine UIP coverage status in the state of West Bengal and three selected Municipal Corporation areas (Calcutta, Howrah and Siliguri) were studied during 1997-98 and 1998-99. Also, UIP coverage status in the 'high risk' areas of the State (areas which reported Polio cases during 1998) was studied during 1998-99. UIP coverage in the state of West Bengal was only 54.3% in 1997-98, which further declined to 48.1% in 1998-99. In the three urban areas, UIP coverage ranged between 57.3%-70.9% in 1997-98, which further declined to 29.6%-47.1% in 1998-99. Antigenwise coverage revealed very poor performance with DPT3, OPV3, and Measles in 1997-98 and further decline in 1998-99. Dropout rate was also very high. In 1998-99 drop-out rate ranged between 30.1% to 54.2% in different studied areas. Some other studies suggested that PPI activities, which are very visible and targetted programme, may adversely affect routine UIP services. There is urgent need for further probing to identify the reasons for such poor state of affairs, keeping PPI angle in mind and to initiate remedial measure urgently.

Vaccines: World Health Organization versus Federal Drug Administration recommended formula

Vaccines produced in accordance with WHO formulas, differ in concentration from those used in United States according to FDA formulas. We aimed to compare the immunogenicity of both formulas. Infants who were 6 weeks old were randomly put into 3 groups to receive 3 doses of vaccines at 6 weeks, 3 months and 5 months of age. The vaccines consisted of Haemophilus influenzae type b vaccine, diphtheria-tetanus-pertussis and oral polio vaccine. Antibody levels for polyribosylribitol phosphate [PRP], tetanus, diphtheria and poliovirus were measured 1 month after the third dose of vaccines. Although diphtheria and tetanus antigens in the FDA formula are half the concentration of the WHO formula, anti-tetanus and anti-diphtheria antibodies were significantly higher. No difference was found between groups regarding oral poliovirus vaccine

Effect of administration of 200,000 IU of vitamin A to women within 24 hrs after delivery on response to PPV administered to the newborn.

OBJECTIVE: To explore the effect of maternal supplementation of vitamin A on the immune response to oral polio vaccine in breastfed infants. DESIGN: Randomized controlled trial. SETTING: Hospital based. METHODS: One hundred mothers having uncomplicated deliveries randomly received either 200,000 IU vitamin A orally (Experimental) or placebo (Control). All the newborns were given a dose of oral polio vaccine within 72 hours after birth and were breastfed. Type specific neutralizing antibodies to polio viruses in test sera diluted from 1:4 to 1:512 and serum retinol levels were determined from the cord blood and at the age of 6 weeks. Breast milk retinol levels were determined at 3, 10, 30, 45 and 90 days of lactation. RESULTS: Seroconversion to OPV and geometric means of antibody titers to the three types of polio viruses were comparable between the groups of infants belonging to the experimental and control mothers. Breast milk retinol levels were significantly higher in the experimental group upto 45-90 days of lactation. Majority of the infants at birth had serum retinol levels < 15 micrograms/dl which improved significantly by 6 weeks irrespective of the maternal supplementation status. CONCLUSIONS: Maternal vitamin A supplementation soon after delivery improves vitamin A intakes of breastfed infants during the first 3 months and has no interference with the seroconversion to a neonatal dose of OPV. OPV administered to newborn in turn has no adverse effect on the vitamin A status of the breastfed infants.

A direct ELISA technique to detect antibodies against polioviruses.

A direct ELISA test was developed to detect circulating antibodies specific to poliovirus types 1, 2 and 3. Specificity of the test was established by using known polio negative and positive sera. The assay was compared with the standard microneutralization test using sera from polio and non polio cases vaccinated and unvaccinated subjects and standard positive sera obtained from WHO/EPI (Geneva). The reproducibility of the results was tested using different batches of the antigen prepared from Sabin strain of poliovirus supplied by ERC Bombay and from Sabin strain of virus obtained from WHO/EPI. ELISA was found to be as sensitive as microneutralization test in detecting seronegatives and was found to be specific to polio by giving negative results with non polio cases. ELISA is thus a rapid and simple method that may be useful for mapping seroepidemiology of poliomyelitis and as a tool for effective surveillance of the disease by offering rapid diagnosis in acute cases.

Prevalence of antibodies to polioviruses & enteroviruses excreted by healthy children in Bombay.

A total of 132 healthy children between the ages one month and 12 yr were surveyed to determine the prevalence of antibodies to the three poliovirus serotypes. Among infants up to six months of age, 73.2, 85.4 and 56.1 per cent had antibodies to poliovirus types 1, 2 and 3, respectively. In children of age groups 7 months to 3 yr and above 3 yr, antibody prevalence to the three poliovirus serotypes was 90.2, 86.9 and 57.4, and 83.3, 96.7 and 76.7 per cent, respectively. Immunization coverage with three doses of OPV exceeded 85 per cent in children above 7 months of age. Low seroprevalence to type 3 poliovirus in the children was conspicuous. Of the 80 faecal samples studied from these children, 24 (30%) were positive for virus. Among these isolates, 16 were poliovirus type 1 and three type 2. Intratypic differentiation revealed that 15 of the 16 poliovirus type 1 isolates were of wild origin. Two out of the three poliovirus type 2 isolates were of oral poliovaccine origin. Our data indicate that in spite of good vaccination coverage wild poliovirus type 1 circulation was endemic in Bombay and; that a large number of children were susceptible to poliovirus type 3 infections.

Poliomyelitis and measles serosurvey in northern Malaysia.

In 1990 the Institute for Medical Research carried out a serosurvey in the state of Kelantan to study the age stratified immune prevalence rates for measles and poliomyelitis. Our findings indicate that 981 out of 1,097 (89%) of the population screened had measles antibodies and more than 90% (366 out of 400) had antibodies to all three serotypes of poliovirus. The susceptible group for measles was infants below one year of age, of whom 53.3% (8/15) did not have measles antibody. Of 400 subjects, 125 (31.3%) who were either incompletely vaccinated or had not been vaccinated against poliomyelitis, had polio neutralizing antibodies to all three poliovirus serotypes, suggesting herd immunity in the population. No high risk age group could be identified for poliomyelitis.