Protective mechanisms of nonneutralizing antiviral antibodies.

Antibodies that can bind to viruses but are unable to block infection in cell culture are known as "nonneutralizing antibodies." Such antibodies are nearly universally elicited following viral infection and have been characterized in viral infections such as influenza, rotavirus, cytomegalovirus, HIV, and SARS-CoV-2. It has been widely assumed that these nonneutralizing antibodies do not function in a protective way in vivo and therefore are not desirable targets of antiviral interventions; however, increasing evidence now shows this not to be true. Several virus-specific nonneutralizing antibody responses have been correlated with protection in human studies and also shown to significantly reduce virus replication in animal models. The mechanisms by which many of these antibodies function is only now coming to light. While nonneutralizing antibodies cannot prevent viruses entering their host cell, nonneutralizing antibodies work in the extracellular space to recruit effector proteins or cells that can destroy the antibody-virus complex. Other nonneutralizing antibodies exert their effects inside cells, either by blocking the virus life cycle directly or by recruiting the intracellular Fc receptor TRIM21. In this review, we will discuss the multitude of ways in which nonneutralizing antibodies function against a range of viral infections.

Reassessing the electrophysiological evidence for categorical perception of Mandarin lexical tone: ERP evidence from native and naïve non-native Mandarin listeners.

Some studies have argued that native speakers of tonal languages have been shown to perceive lexical tone continua in a more categorical manner than speakers of non-tonal languages. Among these, Zhang and colleagues (NeuroReport 23 (1): 35-9) conducted an event-related potential (ERP) study using an oddball paradigm showing that native Mandarin speakers exhibit different sensitivity to deviant tones that cross category boundaries compared to deviants that belong to the same category as the standard. Other recent ERP findings examining consonant voicing categories question whether perception is truly categorical. The current study investigated these discrepant findings by replicating and extending the Zhang et al. study. Native Mandarin speakers and naïve English speakers performed an auditory oddball detection test while ERPs were recorded. Naïve English speakers were included to test for language experience effects. We found that Mandarin speakers and English speakers demonstrated qualitatively similar responses, in that both groups showed a larger N2 to the across-category deviant and a larger P3 to the within-category deviant. The N2/P3 pattern also did not differ in scalp topography for the within- versus across-category deviants, as was reported by Zhang et al. Cross-language differences surfaced in behavioral results, where Mandarin speakers showed better discrimination for the across-category deviant, but English speakers showed better discrimination for within-category deviants, though all results were near-ceiling. Our results therefore support models suggesting that listeners remain sensitive to gradient acoustic differences in speech even when they have learned phonological categories along an acoustic dimension.