Monoclonal-antibody (MAb)-resistant mutants were used to map antigenic sites on foot-and-mouth disease virus (FMDV), which resulted in the identification of neutralizing epitopes in the flexible ?G-?H loop in VP1. For FMDV SAT2 viruses, studies have shown that at least two antigenic sites exist. By use of an infectious SAT2 cDNA clone, 10 structurally exposed and highly variable loops were identified as putative antigenic sites on the VP1, VP2, and VP3 capsid proteins of SAT2/Zimbabwe (ZIM)/7/83 (topotype II) and replaced with the corresponding regions of SAT2/Kruger National Park (KNP)/19/89 (topotype I). Virus neutralization assays using convalescent-phase antisera raised against the parental virus, SAT2/ZIM/7/83, indicated that the mutant virus containing the TQQS-to-ETPV mutation in the N-terminal part of the ?G-?H loop of VP1 showed not only a significant increase in the neutralization titer but also an increase in the index of avidity to the convalescent-phase antisera. Furthermore, antigenic profiling of the epitope-replaced and parental viruses with nonneutralizing SAT2-specific MAbs led to the identification of two nonneutralizing antigenic regions. Both regions were mapped to incorporate residues 71 to 72 of VP2 as the major contact point. The binding footprint of one of the antigenic regions encompasses residues 71 to 72 and 133 to 134 of VP2 and residues 48 to 50 of VP1, and the second antigenic region encompasses residues 71 to 72 and 133 to 134 of VP2 and residues 84 to 86 and 109 to 11 of VP1. This is the first time that antigenic regions encompassing residues 71 to 72 of VP2 have been identified on the capsid of a SAT2 FMDV.

Human rhinovirus (HRV) is a non-enveloped virus of the picornavirus family and is responsible for respiratory infections (common colds) costing billions of dollars ($) annually. There remains no vaccine or licensed drug to prevent or reduce infection. Related members of the picornavirus family include significant pathogens such as poliovirus, enterovirus 71 and foot-and-mouth disease virus, for which improved control measures are also required. A fundamental step in virus infection is the delivery of the viral genetic material through the barrier of the cellular membrane. Viruses such as HIV and influenza are enveloped in an outer membrane which can fuse with the host cell membrane to allow the viral genome to penetrate into the cytoplasm. However, non-enveloped viruses such as picornaviruses lack a membrane and the mechanisms for penetration of the membrane by these viruses remain poorly understood. The capsid protein VP4 has previously been implicated in the delivery of the picornavirus genome. In this study we demonstrate that HRV VP4 interacts with membranes to make them permeable by the formation of multimeric, size-selective membrane pores with properties consistent with the transport of viral genome through the membrane. This function of VP4 provides a novel antiviral target for this family of viruses.

To eliminate incursions of foot-and-mouth disease (FMD) quickly, a combination of measures, including emergency vaccination, can help block the spread of infection. For the earliest recovery of the FMD-free status for trade, without the slaughter of uninfected vaccinated animals, a serosurvey for antibodies to FMD virus non-structural proteins (NSP) must be used to substantiate absence of occult virus infections. Areas of doubt over requirements for post-vaccination serosurveillance and its feasibility include the required and achievable confidence, the amount of sampling necessary, and the appropriate responses to and consequences of different seropositive findings. This derives largely from uncertainty over the extent of localised pockets of virus infection that may remain within vaccinated populations and the circumstances that permit this. The question therefore remains whether tests are sufficiently sensitive and specific to detect and eliminate infected animals, without excessive culling of uninfected animals, before vaccinated animals mix with non-vaccinated livestock when movement restrictions are lifted. It is recommended to change the rationale for serosurveillance after emergency vaccination. Only when emergency vaccination is used in limited outbreaks is it possible to test and cull comprehensively, an approach compatible with a three-month minimum period to recover the FMD-free status. In other situations, where emergency vaccination is used, such as dealing with large outbreaks in animal-dense regions and where the onset of vaccination has been delayed, post-vaccination serosurveys should be targeted and focus on providing an assurance to detect higher levels of infection, in case of inadequate control measures. As this provides less assurance of absence of infection, the approach would be compatible with a six-month waiting period for free-status recovery and should be complemented by other methods to provide evidence that vaccination and control measures have been effectively implemented, as these are the best guarantee against continuing virus transmission.

The aim of this study was to compare and correlate antibody titres against porcine circovirus type 2 (PCV2) in porcine sera (n=1270) obtained by immunoperoxidase monolayer assay (IPMA) with the results of three commercial ELISAs (designated E1, E2 and E3). The correlation between IPMA and ELISA results was excellent (r(2) >= 0.90). Compared to IPMA, E2 had the highest sensitivity (93.0%), followed by E3 (90.1%) and E1 (85.0%); the specificity was 100% for all tests. All three commercial ELIsAs had predictive values similar to those of IPMA and could be used to monitor antibody responses against PCV2 infection and/or vaccination.