Anti-RSV Polyclonal antibody

Background:Cleavage of the inactive precursor fusion protein (F0) of respiratory syncytial virus (RSV) at two furin-recognition sites is required for membrane fusion activity, and the cleavage releases the twenty-seven amino acid peptide (p27). However, a recent study shows that p27 was an immunodominant epitope in RSV infected children, indicating that p27 was recognized as an immunogen. In the present study, we investigated the immunogenicity of p27 in an immunocompromised population of adults by measuring serum and mucosal antibody responses to p27 in samples from adult hematopoietic cell transplant (HCT) recipients.Methods:We prospectively enrolled a cohort of RSV infected HCT recipients. Serum and nasal-wash samples were obtained within the first week of RSV infection (acute) and 3 to 5 weeks post-infection (convalescent). We quantified the serum and mucosal IgG and IgA anti-p27 antibodies by a RSV/A p27 peptide enzyme-linked immunosorbent assay (ELISA) and serum and mucosal p27 like antibodies (P(27)LA) by a p27 competitive antibody (P(27)CA) assay.Results:The lower limit of detection for the ELISA and P(27)CA assays was 0.2 and 50 ng/mL, respectively with no cross-reaction detected with a panel of monoclonal antibodies targeting pre-fusion and post-fusion antigenic sites. P27 antibodies were detected at nanogram concentration in sera and nasal washes in the majority of RSV infected HCT recipients. However, there was no significant difference in the geometric mean antibody concentrations between the acute and convalescent sera (except for serum P(27)LA), between HCT recipients who shed RSV <14 days and >= 14 days, as well as between RSV/A and RSV/B infected HCT recipients. In addition, approximately 30% of HCT recipients had a 4-fold or greater decrease in mucosal IgG and IgA anti-p27 antibodies during viral clearance.Conclusion:In conclusion, in RSV naturally infected adult HCT recipients, the antibodies against p27 were detectable in both serum and nasal wash samples with higher concentration in serum than that in nasal washes. However, nearly 30% of RSV infected HCT recipients had a significant decrease in their mucosal anti-p27 antibody, suggesting that IgG and IgA anti-p27 antibodies were binding to either free viruses or RSV infected cells containing p27, and that anti-p27 antibodies in the respiratory tract were part of the mucosal antibody response in controlling RSV infection.

Author summary Over 70% of all known plant viruses are transmitted by specific arthropods, mainly including planthoppers, leafhoppers, aphids and whiteflies. Plant viruses with persistent relationships must overcome multiple barriers. Among these barriers, midgut and salivary glands are first and last barriers to the viral transmission. The interactions of host factors and virus in the insect midguts and salivary glands provide critical information regarding viral spread in the insect vector and subsequent infection of host plants. However, the precise mechanisms is still lacking. Here, we found that the specific interaction between a alpha-tubulin 2 ofLaodelphax striatellus(SBPH) (LsTUB) and a nonstructural protein 3 (NS3)Rice stripe virus(RSV) mediates the passage of RSV through midgut and salivary glands, thereby leading to successful horizontal transmission. Our results confirm novel functions of LsTUB and NS3 in RSV transmission in insect vector. LsTUB may be a promising target for blocking horizontal transmission of RSV. These insights provide a better understanding of the interaction between plant viruses and vectors and may develop novel methods to control the systemic spread of plant viruses. Rice stripe virus(RSV, genusTenuivirus, familyPhenuiviridae) is the causal agent of rice stripe disease transmitted by the small brown planthopper (SBPH,Laodelphax striatellus) in a persistent propagative manner. The midgut and salivary glands of SBPH are the first and last barriers to the viral circulation and transmission processes, respectively; however, the precise mechanisms used by RSV to cross these organs and transmit to rice plants have not been fully elucidated. We obtained the full-length cDNA sequence ofL.striatellus alpha-tubulin 2(LsTUB) and found that RSV infection increased the level of LsTUBin vivo. Furthermore, LsTUB was shown to co-localize with RSV nonstructural protein 3 (NS3)in vivoand bound NS3 at positions 74-76 and 80-82in vitro. Transient gene silencing ofLsTUBexpression caused a significant reduction in detectable RSV loads and viralNS3expression levels, but had no effect on NS3 silencing suppressor activity and viral replication in insect cells. However, suppression of LsTUB attenuated viral spread in the bodies of SBPHs and decreased RSV transmission rates to rice plants. Electrical penetration graphs (EPG) showed that LsTUB knockdown by RNAi did not impact SBPH feeding; therefore, the reduction in RSV transmission rates was likely caused by a decrease in viral loads inside the planthopper. These findings suggest that LsTUB mediates the passage of RSV through midgut and salivary glands and leads to successful horizontal transmission.