Padronização de teste para quantificar anticorpos anti-poliovírus utilizando vírus vacinal / Standardization of a test for quantifying the antibodies against poliovirus using the vaccine virus

A poliomielite é uma doença endêmica no Afeganistão e no Paquistão, apesar dos esforços para ser erradicada, representando uma ameaça para outros países principalmente devido às viagens internacionais. A Organização Mundial da Saúde (OMS) tem como objetivo erradicar a poliomielite causada pelo poliovírus selvagem no mundo. O requisito essencial para a erradicação da poliomielite é a eliminação da cepa do poliovírus selvagem, que é empregada no teste padrão-ouro. Com o intuito de auxiliar na erradicação do poliovírus selvagem, o objetivo deste estudo foi modificar o teste padrão-ouro usando o poliovírus derivado da vacina oral atenuada. Foram testados 63 soros pelo ensaio de neutralização utilizando-se antígenos vacinais. A concordância do sorotipo 1 (k=0,74) foi considerada substancial, enquanto o sorotipo 2 (k=1,00) e sorotipo 3 (k= 0,95) foram consideradas quase perfeitas. A sensibilidade dos testes de soroneutralização utilizando os sorotipos 1, 2 e 3 foi de 94,83%, 100,00% e 100,00%, respectivamente. Em conclusão, o ensaio com antígenos vacinais pode ser usado como procedimento laboratorial seguro, especialmente em estudos de vigilância em larga escala.

Poliomyelitis is an endemic disease in Afghanistan and Pakistan in despite of the efforts to eradicate it, and it represents a threat to other countries mainly due to the international trips. The World Health Organization (WHO) aims at eradicating the polio disease worldwide. An essential requirement for eradicating the poliomyelitis is the elimination of the wild poliovirus strain, which is employed in the gold standard test. As a support for the eradication of wild poliovirus, the present study aimed at modifying the gold standard test by using poliovirus derived from the oral attenuated vaccine. Sixty-three sera samples were tested by neutralization assay using vaccine antigens. The degree of agreement of the serotype 1 (k=0.74) was considered substantial, while the serotype 2 (k=1.00) and 3 (k= 0.95) showed almost perfect agreement. The sensitivity of serotypes 1, 2 and 3 was 94.83%, 100.00% and 100.00%, respectively. In conclusion, the assay with the vaccine antigens can be used as a safe application, especially for large-scale surveillance studies.

Real-time reverse transcription-polymerase chain reaction assays for identification of wild poliovirus 1 & 3.

Background & objectives: The poliovirus serotype identification and intratypic differentiation by real-time reverse transcription-polymerase chain reaction (rRT-PCR) assay is suitable for serotype mixtures but not for intratypic mixtures of wild and vaccine poliovirus strains. This study was undertaken to develop wild poliovirus 1 and 3 (WPV1 and WPV3) specific rRT-PCR assays for use. Methods: Specific primers and probes for rRT-PCR were designed based on VP1 sequences of WPV1 and WPV3 isolated in India since 2000. The specificity of the rRT-PCR assays was evaluated using WPV1 and WPV3 of different genetic lineages, non-polio enteroviruses (NPEVs) and mixtures of wild/wild and wild/Sabin vaccine strains. The sensitivity of the assays was determined by testing serial 10-fold dilutions of wild poliovirus 1 and 3 stock suspensions of known titre. Results: No cross-reactivity with Sabin strains, intertypic wild poliovirus isolates or 27 types of NPEVs across all the four Enterovirus species was found for both the wild poliovirus 1 and 3 rRT-PCR assays. All WPV1 and WPV3 strains isolated since 2000 were successfully amplified. The rRT-PCR assays detected 104.40CCID50/ml of WPV1 and 104.00CCID50/ml of WPV3, respectively either as single isolate or mixture with Sabin vaccine strains or intertypic wild poliovirus. Interpretation & conclusions: rRT-PCR assays for WPV1 and WPV3 have been validated to detect all the genetic variations of the WPV1 and WPV3 isolated in India for the last decade. When used in combination with the current rRT-PCR assay testing was complete for confirmation of the presence of wild poliovirus in intratypic mixtures.

Prevalence of prolonged and chronic poliovirus excretion among persons with primary immune deficiency disorders in the Philippines

OBJECTIVES: As part of the global initiative to eradicate poliovirus infections this study aims to: (1) estimate the prevalence of vaccine-derived poliovirus excretion among persons diagnosed with primary immune (B-cell or combined B/T-cell) deficiency disorders (PIDD) in the Philippines; (2) describe clinical features of these PIDD patients excreting poliovirus; (3) genetically characterize vaccine-derived polioviruses isolated from persons with PIDDs; and (4) determine the duration of poliovirus excretion among subjects who tested positive for vaccine-derived poliovirus excretion. METHODS: Seventy-one (71) Filipino patients (ages 0-35 years of age) with PIDD were recruited retrospectively and prospectively over a period of 16 months. The study participants, after informed consent and administration of a questionnaire for baseline data, underwent further testing of quantitative immunoglobulin levels (IgG, IgA, and IgM) and stool poliovirus isolation using two stool samples. Stool specimens which tested positive for the poliovirus were sent to the Regional Reference Laboratory in Australia for further characterization by Intratypic Differentiation (ITD) and Vaccine-derived polioviruses (VDPV) real-time PCR. These participants were then monitored on a monthly basis until laboratory tests identified two sequential months of negative poliovirus stool specimens. RESULTS: Seventy-one (71) patients underwent interview and quantitative serum immunoglobulin testing. However, one patient expired prior to stool isolate collection. This study, then, documented that none of the remaining 70 Filipino individuals (0-35 years old) with confirmed or suspected PIDDs chronically excreted immunodeficiency-associated vaccine-derived poliovirus (IVDPV). One patient who was a recent OPV-recipient excreted poliovirus Sabin-like 1 transiently (less than 1 month) and two patients excreted non polio-enteroviruses. CONCLUSIONS: Chronic and prolonged poliovirus excretion appears to be uncommon among Filipino patients with diagnosed Primary Immunodeficiency Disease Disorders. However, as part of the continuing global initiative for poliovirus eradication, vigilance is still necessary in patients with primary immunodeficiency diseases. Adequate identification of these patients followed by monitoring their capacity for viral excretion and environmental contamination may be necessary to achieve this goal.

Study on the Fast Testing Strategy for identifying the wild poliovirus Ⅰ / 中华流行病学杂志

Objective To explore the Fast Testing Sstrategy (FTS) for wild poliovirus Ⅰ (WP1).Methods Epidemiological investigations were carried out on 671 students from WP1 epidemic areas in China.A set of real time RT-PCR assays,including panenterovirus testings (PE) assay,poliovirus serotypings(PS) assay and the assay distinguishing wild strain from vaccine strain of poliovirus Ⅰ (DWV) were introduced into the screening program for WPV1 to replace the conventional RT-PCR,recommended by the China National Polio Laboratory (GNPL).Additionally,sensitivities of all the assays were assessed by poliovirus type Ⅰ to Ⅲ (Sabin stain) and the isolated WPV I.Results ( 1 ) 33 non-poliovirus enterovirus (NPEV) cases were detected,with 16 polio vaccinerelated cases including 5 polio Ⅰ,1 polio Ⅱ,3 polio Ⅲ,1 polio Ⅰ +Ⅱ,4 polio Ⅰ + Ⅲ and 2 polio Ⅰ + Ⅱ + Ⅲ.Three WPV 1 cases were also detected in this study and confirmed by GNPL.(2) For polio virus vaccine strain,sensitivities of the set of real time RT-PCR assays ranged from 1 to 100 times than that of the in-housc RT-PCR assay.The sensitivities of PE and PS assays for the detection of polio Ⅱ were 100 times than that of the RT-PCR assay and the sensitivity of DWV assay used for the detection of polio Ⅰ were 10 times than that of the RT-PCR assay.For WPV1,the sensitivity of three real time RT-PCR was 10 times higher than that of the RT-PCR assay.Conclusion The novel FTS for WPV I suggested by this study would include PE,PS and DWV.It not only could greatly shorten the testing time but also more sensitive than the RT-PCR and suited for emergency detection for WPV1.

Eradicating Polio: It's Feasibility in Near Future.

Continuous wild poliovirus transmission despite 12 years of intensive surveillance has raised serious questions about the feasibility of polio eradication programme with current strategy in near future. At present most of the cases are confined to four endemic countries, which are causing sporadic outbreaks in non-endemic areas. India has experienced a significant increase in number of cases reported in 2006 compared to previous year. Outbreaks originated in western UP which was due to the accumulation of susceptibles between the last outbreak in 2002 and early 2006. Substantial improvement has been observed in strategies of polio eradication but still there are gaps in the programme implementation which needs immediate attention so that goal of polio eradication can be achieved at the earliest opportunity. Even though there are many issues but there are also many factors, which favour polio eradication. These factors include new tool in form of m OPV, natural immunity due to recent outbreak, limiting international spread of polio, new researches to guide programme in right direction, political commitments from endemic countries, etc. 2008 presents the best opportunity ever to interrupt wild polio virus transmission which will lead to global eradication of Polio. Since global eradication is within sight, it is scientifically possible to eradicate the disease in near future.