Microbiota-independent antiviral effects of antibiotics on poliovirus and coxsackievirus.

Coxsackieviruses primarily infect the gastrointestinal tract of humans, but they can disseminate systemically and cause severe disease. Using antibiotic treatment regimens to deplete intestinal microbes in mice, several groups have shown that bacteria promote oral infection with a variety of enteric viruses. However, it is unknown whether antibiotics have microbiota-independent antiviral effects for enteric viruses or whether antibiotics influence extra-intestinal, systemic infection. Here, we examined the effects of antibiotics on systemic enteric virus infection by performing intraperitoneal injections of either coxsackievirus B3 (CVB3) or poliovirus followed by quantification of viral titers. We found that antibiotic treatment reduced systemic infection for both viruses. Interestingly, antibiotics reduced CVB3 titers in germ-free mice, suggesting that antibiotic treatment alters CVB3 infection through a microbiota-independent mechanism. Overall, these data provide further evidence that antibiotics can have noncanonical effects on viral infection.

Immunogenicity and safety of a DTaP-IPV/Hib pentavalent vaccine given as primary and booster vaccinations in healthy infants and toddlers in Japan.

BACKGROUND: Globally, the use of single DTaP-IPV/Hib vaccines that combine DTaP-IPV and Hib is widespread, but in Japan vaccination is usually concomitant at separate sites. The immunogenicity and safety of a primary vaccination series and booster of a combined pentavalent DTaP-IPV/Hib vaccine were evaluated and compared to separate administration of DTaP-IPV and Hib in Japanese infants. METHODS: Healthy Japanese infants were administered DTaP-IPV/Hib (Group A: N = 207) or DTaP-IPV + Hib (Group B: N = 207) by the subcutaneous (SC) or DTaP-IPV/Hib by the intramuscular (IM) route (Group C: N = 10). All subjects received a 3-dose primary vaccination series and a booster. Non-inferiority (Group A versus Group B) was tested post-primary series and subsequent post hoc analyses were performed for anti-Hib. Safety was assessed by parental reports. RESULTS: Non-inferiority for SC administration of Group A versus Group B for the primary series was demonstrated for antibody responses to all antigens except Hib using the threshold of 1.0 µg/mL. Post hoc analyses for anti-Hib demonstrated non-inferiority for the primary series response using 0.15 µg/mL, and for pre-booster antibody persistence and the booster response using 0.15 µg/mL and 1.0 µg/mL. The immune response was similar for each antigen following SC or IM administration. There were no safety concerns in any group, and a lower incidence of injection sites for the IM route was observed as expected. CONCLUSIONS: These data show the good immunogenicity and safety profile of the DTaP-IPV/Hib vaccine as a 3-dose infant primary series followed by a booster in the second year of life in Japan.

Contenção do poliovírus nos laboratórios brasileiros

Plaque and growth characteristics of different polioviruses isolated from acute flaccid paralysis in Northern Nigeria.

OBJECTIVE: To determine some virulent trait-related properties of poliovirus isolates from children with acute flaccid paralysis following vaccination with oral polio vaccine (OPV). DESIGN: Six polioviruses earlier characterised into wild, vaccine-derived and OPV-like were studied using the plaque morphology and growth kinetics at supra-optimal temperature. SETTING: Department of Virology, University of Ibadan, Nigeria. SUBJECTS: Polio isolates from six children who developed acute flaccid paralysis following vaccinations with various doses of OPV were used. All the children were located in the Northern part of the country where poliovirus is still circulating. MAIN OUTCOME MEASURES: The two vaccine-derived polioviruses acquired wild type characteristics. RESULTS: All the six poliovirus isolates developed different forms of plaques ranging from tiny, small and large. The plaque formed could however not be used to identify the different isolates. Growth of the different isolates at supra-optimal temperature showed that the three wild polioviruses grew to a higher titre when compared with the Sabin 2 control. The two vaccine derived isolates behaved like the wild poliovirus while the OPV-like virus acquired an intermediate characteristics between wild and sabin. CONCLUSION: The wild polioviruses represented in this study are among the last vestiges of the circulating polioviruses found in the world. It is possible that the observed biological properties of wild types 1 and 3 described in the study are typical of the West African polioviruses. These properties will provide useful previews to the final identification of some important clinical isolates especially type 1 which may grow rapidly in cell culture.

No evidence of prolonged enterovirus excretion in HIV-seropositive patients.

Mutations frequently occur in oral poliovirus vaccine (OPV) strains upon replication in the human intestine. These strains occasionally revert to being neurovirulent. The more prolonged the excretion of OPV, the higher the risk of reversion. OPV strains can be secreted for several months in humans presenting humoral immune system deficiencies. The duration of excretion of OPV strains or other enteroviruses in individuals infected with the human immunodeficiency virus (HIV) is unknown. We investigated whether HIV infection, which is very prevalent in the Central African Republic, causes prolonged excretion of enteroviruses and, in particular, of OPV strains in adults. We studied 28 HIV-infected adults living with children who were immunized with OPV during national immunization days (NIDs). Blood samples were collected to confirm HIV status and to evaluate immunodeficiency before the NIDs. Stool samples for enterovirus isolation were also collected before the NIDs, between the two rounds of immunization and 2, 4 and 6 months after the second round of immunization. No poliovirus was isolated from any stool sample. Eight enteroviruses were isolated from eight adults (maximum one strain per patient). Enteroviruses were not more frequently isolated from severely immunodeficient patients. Thus, HIV-infected adults do not appear to be at high risk of infection with OPV strains and the excretion of enteroviruses (and thus of polioviruses) does not seem to be prolonged in HIV-infected adults.

Site analysis of recombinant and mutant poliovirus isolates of Sabin origin from patients and from vaccinees.

Recombination in vaccine strains of polioviruses is a very frequent phenomenon. In the present report, 12 strains isolated from patients after OPV administration and healthy vaccinees were investigated for the identification of recombinant strains as well as for the further analysis of their recombination types and the localization of the recombination sites. The identification of these strains was achieved through reverse transcription, polymerase chain reaction and restriction fragment length polymorphism assays applied to four sequences of the viral genome, which are located in 5'UTR, VP3-VP1, 2C and 3C-D regions. The exact recombination sites were determined by sequencing. Four of the 12 included strains were recombinant in one or more regions. Two of the recombinant strains had an S2/S1 recombination, localized in 3C-D region, one had an S3/S2 localized in 2C and finally a birecombinant strain was identified having an S3/S2/S1 recombination type, with the two recombinations localized in 2C and 3D regions, respectively. The significance of the recombination types and sites observed concerning the viral viability are discussed.

Genetic recombination in wild-type poliovirus.

Poliovirus isolates were screened for recombinants by combined analysis of two distant polymorphic segments of the poliovirus genome (one in the capsid and the other in the polymerase-coding region). Using a restriction fragment length polymorphism (RFLP) assay, a high number of recombinant genomes was found among vaccine-derived strains excreted by poliovirus vaccine vaccinees or vaccine-associated paralytic poliomyelitis cases. Some of these subjects carried a wild-type poliovirus (non-vaccine-specific) nucleotide sequence in the 3' part of the genome. Using a similar approach, a collection of wild-type poliovirus strains isolated in South India between 1985 and 1993 was screened for recombinants. Genotypes were defined by the parallel application of RFLP assays and genomic sequencing of the capsid protein VP1 and the 3D polymerase polypeptide. Analyses revealed several instances where the position of an isolate on the phylogenic tree for the capsid protein-coding segment did not agree with its position on the tree for the polymerase-coding region. In this way, several wild-type/wild-type and wild-type/vaccine recombinants could be identified, indicating that recombination is encountered commonly in the natural evolution of poliovirus strains.

Virologic surveillance and progress toward poliomyelitis eradication--Eastern Mediterranean Region, 1995-September 1998.

In 1988, the Regional Committee of the Eastern Mediterranean Region (EMR) of the World Health Organization (WHO) resolved to eliminate poliomyelitis by 2000. Substantial progress toward polio eradication has been achieved in the region. Surveillance for cases of acute flaccid paralysis (AFP) and examination of stool specimens from AFP cases for the presence of poliovirus provide critical data to target supplemental vaccination activities. This report summarizes the progress in AFP and poliovirus surveillance in EMR from 1995 through September 1998 and highlights the importance of virologic investigations to determine whether viruses isolated represent indigenous transmission, importations, or laboratory contamination.

The balance between persistent virus infection and immune cells determines demyelination.

We addressed the contributions of persistent virus infection and immune cells to the pathogenesis of Theiler's virus-induced demyelination, a model for human multiple sclerosis. We developed a model involving the transfer of spleen cells into immunodeficient C.B-17-scid (SCID) mice, which normally die of overwhelming virus encephalitis without demyelination when infected with Theiler's virus. Adoptive transfer of nonimmune spleen cells from BALB/c mice into SCID mice resulted in the survival of all mice. However, these mice developed extensive demyelination and virus Ag/RNA persistence in the spinal cord white matter. The most demyelination was observed when mice received an intermediate number of spleen cells (1.8-7.5 x 10(6)), whereas too few cells (0.5 x 10(6)) did not ameliorate the SCID phenotype, and too many cells (30 x 10(6)) resulted in almost complete viral clearance with minimal demyelination. Adoptive transfer of spleen cells depleted of either CD4+ or CD8+ T cells produced vacuolar demyelination associated with virus persistence. In contrast, reconstitution with both CD4+ and CD8+ T cells produced less severe demyelination and partial clearance of virus. These experiments support the hypothesis that demyelination is the result of a balance between persistent virus infection and immune injury mediated by either CD4+ or CD8+ T cells.

Pathogenetic mechanisms of post-polio syndrome: morphological, electrophysiological, virological, and immunological correlations.

To understand the mechanism of post-poliomyelitis muscular atrophy (PPMA) and the post-polio syndrome (PPS) in general, we performed the following studies: (1) histopathology in spinal cord sections from patients who died 9 days to 44 years after acute paralytic poliomyelitis; (2) enzyme histochemistry, immunocytochemistry (for lymphocyte subsets, MHC antigens and N-CAM) and polymerase chain reaction (PCR) for poliovirus RNA in the muscle biopsies from symptomatic or asymptomatic muscles of post-polio patients; (3) determination of lymphocyte subsets and circulating IgG or IgM antibodies against GM1 and poliovirus; (4) virological studies in the spinal fluid for oligoclonal bands and search for poliovirus genome with PCR; (5) electrophysiological studies including single fiber EMG, fiber density and macro-EMG; and (6) [31P] exercise MRS spectroscopy on previously affected muscles to search for a metabolic correlate of fatigue. These studies concluded that in PPS a continuing dysfunction is present in the spinal cord motor neurons, resulting in ongoing muscle denervation and reinnervation first evident at the axonal branch points. Symptoms are related to attrition of the oversprouting motor neurons which after a period of time cannot support all their axonal sprouts, resulting in failure of re-reinnervation. In some patients with PPS there is also an ongoing immune activation and presence of defective viral particles in the spinal fluid. However, their role in the pathogenesis of PPS is presently unknown.

CD3+/TCR-alpha beta- cells are important in protecting spinal cord tissues against Theiler's virus strain GD VII infection.

Intravenous infection with Theiler's virus strain GD VII causes acute encephalomyelitis in mice. Endogenous IFN-gamma produced in the spinal cord is important to protect the tissue in mice infected with this virus. Neither CD4+ cells nor CD8+ cells infiltrated the spinal cords of infected mice until Day 9 postinfection. However, the number of CD3+/TCR-gamma delta+ cells increased in the spinal cords of mice infected with the virus. These cells resided in the spinal cords of normal mice, and produced IFN-gamma as a result of stimulation by immobilized anti-CD3 mAb. Elimination of CD3+ cells by the administration of a specific mAb augmented viral replication and suppressed production of endogenous IFN-gamma. Depletion of TCR-alpha beta+ cells and ASGM1+ cells did not affect the viral replication, and did not alter the production of IFN-gamma. Therefore, CD3+/TCR-alpha beta- cells producing IFN-gamma play an important role in the protection of the spinal cord against Theiler's virus infection. These results suggest that CD3+/TCR-alpha beta- cells might be identical to TCR-gamma delta+ cells.

Outbreak of paralytic poliomyelitis in Namibia.

The last confirmed case of poliomyelitis in Namibia had been reported in 1988. However, between Nov 8, 1993, and Jan 7, 1994, 27 cases of paralytic poliomyelitis were confirmed in the country. The outbreak was limited to the south health region; at least 80% of infants in this region have received four doses of oral poliovaccine (OPV) by the age of 1 year. Acute flaccid paralysis (AFP) was the predominant clinical presentation during the outbreak. The patients' ages ranged from 13 months to 12 years; 24 were younger than 5 years. Of the 26 patients whose vaccine status was known, 14 had received four doses of OPV, 6 had one or two doses, and 6 no vaccine. Genotypic analysis showed 86% homology of outbreak isolates with a 1982 Namibian isolate and west African isolates. Factors that may have had a role in the outbreak include establishment of a pool of susceptible people, rapid urbanisation, inadequate sanitation, poor water supply, and possible endemicity of poliovirus in neighbouring areas. Epidemics can occur in areas of high vaccine coverage. Our findings emphasise the need to improve AFP surveillance activities and the estimation of vaccine coverage to identify areas of potential susceptibility for outbreaks.