Effect of time at temperature on wild poliovirus titers in stool specimens

AbstractBackgroundThe effect of transport temperature on the viability of poliovirus in stool specimens from paralyzed cases has not been tested. Quality assurance of programmatic indicators will be necessary in the final phase of polio eradication.ObjectiveTo estimate the effect of time at elevated temperatures on wild poliovirus titers in stool specimens.MethodsWe exposed aliquots of pooled wild poliovirus type 1 specimens to elevated temperatures (27°C, 31°C, and 35°C) for varying time periods up to 14 days. We determined the virus titer of these aliquots and created decay curves at each temperature to estimate the relationship between time at temperature and virus titer.ResultsWe found significantly different slopes of decay at each temperature. The negative slopes increased as the temperature increased.ConclusionsWhile poliovirus in stool remains relatively stable at moderately elevated temperature, transport at higher temperatures could impact sample integrity and virus isolation results

The potential impact of expanding target age groups for polio immunization campaigns

Background: Global efforts to eradicate wild polioviruses (WPVs) continue to face challenges due to uninterrupted endemic WPV transmission in three countries and importation-related outbreaks into previously polio-free countries. We explore the potential role of including older children and adults in supplemental immunization activities (SIAs) to more rapidly increase population immunity and prevent or stop transmission. Methods: We use a differential equation-based dynamic poliovirus transmission model to analyze the epidemiological impact and vaccine resource implications of expanding target age groups in SIAs. We explore the use of older age groups in SIAs for three situations: alternative responses to the 2010 outbreak in Tajikistan, retrospective examination of elimination in two high-risk states in northern India, and prospective and retrospective strategies to accelerate elimination in endemic northwestern Nigeria. Our model recognizes the ability of individuals with waned mucosal immunity (i.e., immunity from a historical live poliovirus infection) to become re-infected and contribute to transmission to a limited extent. Results: SIAs involving expanded age groups reduce overall caseloads, decrease transmission, and generally lead to a small reduction in the time to achieve WPV elimination. Analysis of preventive expanded age group SIAs in Tajikistan or prior to type-specific surges in incidence in high-risk areas of India and Nigeria showed the greatest potential benefits of expanded age groups. Analysis of expanded age group SIAs in outbreak situations or to accelerate the interruption of endemic transmission showed relatively less benefit, largely due to the circulation of WPV reaching individuals sooner or more effectively than the SIAs. The India and Nigeria results depend strongly on how well SIAs involving expanded age groups reach relatively isolated subpopulations that sustain clusters of susceptible children, which we assume play a key role in persistent endemic WPV transmission in these areas. Conclusions: This study suggests the need to carefully consider the epidemiological situation in the context of decisions to use expanded age group SIAs. Subpopulations of susceptible individuals may independently sustain transmission, which will reduce the overall benefits associated with using expanded age group SIAs to increase population immunity to a sufficiently high level to stop transmission and reduce the incidence of paralytic cases

Biological and technical variables affecting immunoassay recovery of cytokines from human serum and simulated vaginal fluid: A multicenter study

The increase of proinflammatory cytokines in vaginal secretions may serve as a surrogate marker of unwanted inflammatory reaction to microbicide products topically applied for the prevention of sexually transmitted diseases, including HIV-1. Interleukin (IL)-1β and IL-6 have been proposed as indicators of inflammation and increased risk of HIV-1 transmission; however, the lack of information regarding detection platforms optimal for vaginal fluids and interlaboratory variation limit their use for microbicide evaluation and other clinical applications. This study examines fluid matrix variants relevant to vaginal sampling techniques and proposes a model for interlaboratory comparisons across current cytokine detection technologies. IL-1β and IL-6 standards were measured by 12 laboratories in four countries, using 14 immunoassays and four detection platforms based on absorbance, chemiluminescence, electrochemiluminescence, and fluorescence. International reference preparations of cytokines with defined biological activity were spiked into (1) a defined medium simulating the composition of human vaginal fluid at pH 4.5 and 7.2, (2) physiologic salt solutions (phosphate-buffered saline and saline) commonly used for vaginal lavage sampling in clinical studies of cytokines, and (3) human blood serum. Assays were assessed for reproducibility, linearity, accuracy, and significantly detectable fold difference in cytokine level. Factors with significant impact on cytokine recovery were determined by Kruskal−Wallis analysis of variance with Dunn’s multiple comparison test and multiple regression models. All assays showed acceptable intra-assay reproducibility; however, most were associated with significant interlaboratory variation. The smallest reliably detectable cytokine differences (P < 0.05) derived from pooled interlaboratory data varied from 1.5- to 26-fold depending on assay, cytokine, and matrix type. IL-6 but not IL-1β determinations were lower in both saline and phosphate-buffered saline as compared to vaginal fluid matrix, with no significant effect of pH. The (electro)chemiluminescence-based assays were most discriminative and consistently detected <2-fold differences within each matrix type. The Luminex-based assays were less discriminative with lower reproducibility between laboratories. These results suggest the need for uniform vaginal sampling techniques and a better understanding of immunoassay platform differences and cross-validation before the biological significance of cytokine variations can be validated in clinical trials. This investigation provides the first standardized analytic approach for assessing differences in mucosal cytokine levels and may improve strategies for monitoring immune responses at the vaginal mucosal interface

Oral Immunization with a Live Coxsackievirus/HIV Recombinant Induces Gag p24-Specific T Cell Responses

The development of an HIV/AIDS vaccine has proven to be elusive. Because human vaccine trials have not yet demonstrated efficacy, new vaccine strategies are needed for the HIV vaccine pipeline. We have been developing a new HIV vaccine platform using a live enterovirus, coxsackievirus B4 (CVB4) vector. Enteroviruses are ideal candidates for development as a vaccine vector for oral delivery, because these viruses normally enter the body via the oral route and survive the acidic environment of the stomach.We constructed a live coxsackievirus B4 recombinant, CVB4/p24(73(3)), that expresses seventy-three amino acids of the gag p24 sequence (HXB2) and assessed T cell responses after immunization of mice. The CVB4 recombinant was physically stable, replication-competent, and genetically stable. Oral or intraperitoneal immunization with the recombinant resulted in strong systemic gag p24-specific T cell responses as determined by the IFN-gamma ELISPOT assay and by multiparameter flow cytometry. Oral immunization with CVB4/p24(73(3)) resulted in a short-lived, localized infection of the gut without systemic spread. Because coxsackieviruses are ubiquitous in the human population, we also evaluated whether the recombinant was able to induce gag p24-specific T cell responses in mice pre-immunized with the CVB4 vector. We showed that oral immunization with CVB4/p24(73(3)) induced gag p24-specific immune responses in vector-immune mice.The CVB4/p24(73(3)) recombinant retained the physical and biological characteristics of the parental CVB4 vector. Oral immunization with the CVB4 recombinant was safe and resulted in the induction of systemic HIV-specific T cell responses. Furthermore, pre-existing vector immunity did not preclude the development of gag p24-specific T cell responses. As the search continues for new vaccine strategies, the present study suggests that live CVB4/HIV recombinants are potential new vaccine candidates for HIV

Characterization of poliovirus variants selected for resistance to the antiviral compound V-073

V-073, a small-molecule capsid inhibitor originally developed for nonpolio enterovirus indications is considerably more potent against polioviruses. All poliovirus isolates tested to date (n = 45), including wild, vaccine, vaccine-derived, and laboratory strains, are susceptible to the antiviral capsid inhibitor V-073. We grew poliovirus in the presence of V-073 to allow for the identification of variants with reduced susceptibility to the drug. Sequence analysis of 160 independent resistant variants (80 isolates of poliovirus type 1,40 isolates each of types 2 and 3) established that V-073 resistance involved a single amino acid change in either of two virus capsid proteins, VP1 (67 of 160 [42%]) or VP3 (93 of 160 [58%]). In resistant variants with a VP1 change, the majority (53 of 67 [79%]) exhibited a substitution of isoleucine at position 194 (equivalent position 192 in type 3) with either methionine or phenylalanine. Of those with a VP3 change, alanine at position 24 was replaced with valine in all variants (n = 93). The resistance phenotype was relatively stable upon passage of viruses in cell culture in the absence of drug. Single-step growth studies showed no substantial differences between drug-resistant variants and the virus stocks from which they were derived, while the resistant viruses were generally more thermally labile than the corresponding drug-susceptible parental viruses. These studies provide a foundation from which to build a greater understanding of resistance to antiviral compound V-073

Poliovirus vaccine shedding among persons with HIV in Abidjan, Cote d’Ivoire

Background. As polio eradication nears, the development of immunization policies for an era without the disease has become increasingly important. Outbreaks due to circulating vaccine-derived poliovirus (VDPV) and rare cases of immunodeficient persons with prolonged VDPV shedding lend to the growing consensus that oral poliovirus vaccine (OPV) use should be discontinued as soon after polio eradication as possible. The present study was conducted to assess whether persons infected with human immunodeficiency virus (HIV) experience prolonged VDPV shedding and serve as a source of reintroduction of virus into the population. Methods. Adults infected with HIV had specimens tested (1) 8 months after a mass OPV campaign, to determine whether poliovirus related to OPV administered during the campaign was present (i.e., prolonged excretion), and (2) starting 7 weeks after a subsequent campaign, to determine whether poliovirus could be detected after the height of OPV exposure. Results. A total of 419 participants were enrolled-315 during the 8-12 months after an OPV campaign held in 2001 and 104 during the 7-13 weeks after a 2002 campaign. No poliovirus was isolated from any participants. Conclusions. It appears unlikely that adults infected with HIV experience prolonged vaccine virus shedding, and, therefore, they probably represent a minimal risk of reintroducing vaccine virus into the population after poliovirus has been eradicated

Identification and validation of clinical predictors for the risk of neurological involvement in children with hand, foot, and mouth disease in Sarawak

Background: Human enterovirus 71 (HEV71) can cause Hand, foot, and mouth disease (HFMD) with neurological complications, which may rapidly progress to fulminant cardiorespiratory failure, and death. Early recognition of children at risk is the key to reduce acute mortality and morbidity. Methods: We examined data collected through a prospective clinical study of HFMD conducted between 2000 and 2006 that included 3 distinct outbreaks of HEV71 to identify risk factors associated with neurological involvement in children with HFMD. Results: Total duration of fever ≥ 3 days, peak temperature ≥ 38.5°C and history of lethargy were identified as independent risk factors for neurological involvement (evident by CSF pleocytosis) in the analysis of 725 children admitted during the first phase of the study. When they were validated in the second phase of the study, two or more (≥ 2) risk factors were present in 162 (65%) of 250 children with CSF pleocytosis compared with 56 (30%) of 186 children with no CSF pleocytosis (OR 4.27, 95% CI2.79–6.56, p < 0.0001). The usefulness of the three risk factors in identifying children with CSF pleocytosis on hospital admission during the second phase of the study was also tested. Peak temperature ≥ 38.5°C and history of lethargy had the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 28%(48/174), 89%(125/140), 76%(48/63) and 50%(125/251), respectively in predicting CSF pleocytosis in children that were seen within the first 2 days of febrile illness. For those presented on the 3rd or later day of febrile illness, the sensitivity, specificity, PPV and NPV of ≥ 2 risk factors predictive of CSF pleocytosis were 75%(57/ 76), 59%(27/46), 75%(57/76) and 59%(27/46), respectively. Conclusion: Three readily elicited clinical risk factors were identified to help detect children at risk of neurological involvement. These risk factors may serve as a guide to clinicians to decide the need for hospitalization and further investigation, including cerebrospinal fluid examination, and close monitoring for disease progression in children with HFMD

Oncolysis of malignant human melanoma tumors by Coxsackieviruses A13, A15 and A18

Many RNA viruses are displaying great promise in the field of oncolytic virotherapy. Previously, we reported that the picornavirus Coxsackievirus A21 (CVA21) possessed potent oncolytic activity against cultured malignant melanoma cells and melanoma xenografts in mice. In the present study, we demonstrate that three additional Group A Coxsackieviruses; Coxsackievirus A13 (CVA13), Coxsackievirus A15 (CVA15) and Coxsackievirus A18 (CVA18), also have similar oncolytic activity against malignant melanoma. Each of the viruses grew quickly to high titers in cancer cells expressing ICAM-1 and intratumoral injection of preformed subcutaneous SK-Mel-28 xenografts in mice with CVA13, CVA15 and CVA18 resulted in significant tumor volume reduction