UB2/UB3/TSH4-anchored transcriptional networks regulate early maize inflorescence development in response to simulated shade.

Increasing planting density has been adopted as an effective means to increase maize (Zea mays) yield. Competition for light from neighbors can trigger plant shade avoidance syndrome, which includes accelerated flowering. However, the regulatory networks of maize inflorescence development in response to high-density planting remain poorly understood. In this study, we showed that shade-mimicking treatments cause precocious development of the tassels and ears. Comparative transcriptome profiling analyses revealed the enrichment of phytohormone-related genes and transcriptional regulators among the genes co-regulated by developmental progression and simulated shade. Network analysis showed that three homologous Squamosa promoter binding protein (SBP)-like (SPL) transcription factors, Unbranched2 (UB2), Unbranched3 (UB3), and Tasselsheath4 (TSH4), individually exhibited connectivity to over 2,400 genes across the V3-to-V9 stages of tassel development. In addition, we showed that the ub2 ub3 double mutant and tsh4 single mutant were almost insensitive to simulated shade treatments. Moreover, we demonstrated that UB2/UB3/TSH4 could directly regulate the expression of Barren inflorescence2 (BIF2) and Zea mays teosinte branched1/cycloidea/proliferating cell factor30 (ZmTCP30). Furthermore, we functionally verified a role of ZmTCP30 in regulating tassel branching and ear development. Our results reveal a UB2/UB3/TSH4-anchored transcriptional regulatory network of maize inflorescence development and provide valuable targets for breeding shade-tolerant maize cultivars.

Seroprevalence of neutralizing antibodies against the respiratory syncytial virus in healthy adults in Guangzhou, southern China.

Respiratory syncytial virus (RSV) is the major cause of pneumonia and bronchiolitis in infants and young children and mediates substantial morbidity and mortality in the elderly and immunocompromised globally. The development of a safe and effective RSV vaccine and an optimized neutralizing antibody (NAb) with strong virus-neutralizing activity is appealing. To gain some detailed knowledge of the humoral immune response to RSV subgroup A (RSV-A) and RSV-B, we investigated the seroprevalence of pre-existing NAbs by using the microneutralization assay in healthy adult from Guangzhou, southern China. We found that the overall seropositive rate was 84.86% for anti-RSV NAbs. Furthermore, the seropositive rates were 68.47% and 73.61% for anti-RSV-A NAbs and anti-RSV-B NAbs, respectively. In addition, although the seropositive rates and NAb levels were not associated with the blood type, type AB individuals displayed higher seropositive rates for anti-RSV-A NAbs with high titer (≥ 288) and anti-RSV-B NAbs, especially those with moderate titer (≥ 72 to < 288). The seropositive rates and titers were comparable between anti-RSV-A NAbs and anti-RSV-B NAbs in the AB blood type group. Interestingly, only when the NAb titer of the serum to RSV-A was not less than 288, was it not less than 18 to RSV-B, and vice versa. These results would be helpful for a better understanding of the human serum NAb responses to RSV-A and RSV-B.

The short fiber knobs of human adenovirus in species F elicit cross-neutralizing antibody responses.

Human adenovirus (HAdV) type 40 in species F (HAdV-F40) and HAdV-F41 represent the third most prevalent causative agents of non-bacterial acute gastroenteritis in infants and young children, following norovirus and rotavirus. Despite their significant contribution to global child morbidity, vaccines to preemptively combat these viruses remain elusive. In this study, we investigate the potential for cross-neutralization between HAdV-F40 and HAdV-F41 using immune sera with the short fiber knob (SFK). We implemented a series of assays to evaluate the responses, including enzyme-linked immunosorbent, micro-neutralization, immunofluorescence, and quantitative polymerase chain reaction. Our results demonstrate that immune sera with HAdV-F40 SFK or HAdV-F41 SFK could effectively neutralize both HAdV-F40 and HAdV-F41, indicating a mutual cross-neutralizing effect. Notably, the immune sera with HAdV-F40 SFK demonstrated a stronger neutralization effect, suggesting the potential to develop a subunit vaccine that can simultaneously counteract both viruses. These findings underscore the potential of SFK immunization in evoking a cross-neutralizing antibody response between HAdV-F40 and HAdV-F41. This suggests a promising avenue for developing subunit vaccines against HAdV-F40 and HAdV-F41 and provides a novel perspective on the potential of neutralizing antibodies to protect against these two types of HAdV.

A Sensitive and High-Throughput Flow Cytometry-Based Assay for Measuring Antibody Neutralization of Human Adenovirus Type 3.

The assessment of neutralization activity is an important step in the evaluation of neutralizing antibodies (NAbs). The traditional methods for measuring the antibody neutralization of human adenovirus type 3 (HAdV-3) are the microneutralization (MN) assay, which has insufficient sensitivity, and the plaque reduction neutralization test (PRNT), which is not suitable for high-throughput screening. Herein, we describe the development of a flow cytometry-based neutralization (FCN) assay for measuring the neutralization of sera, cell culture supernatants, and chimeric antibodies against HAdV-3 on the basis of a recombinant HAdV-3 (rHAdV-3) construct expressing the enhanced green fluorescent protein (EGFP). For flow cytometry-based assays, the optimal cell confluence was determined as 90%, and the virus was titrated using the assay. The established FCN assay follows the percentage law and an optimal MOI of not less than 5 × 10-4 was determined by using a purified chimeric antibody. In addition, comparison of the anti-HAdV-3 NAb titers of 72 human serum samples by the MN and FCN assays, showed that both assays correlated strongly with each other. Our FCN assay was an improvement over the MN assay because the observation period was reduced from 3 to 1 days and data analysis could be performed objectively and robotically. Importantly, the newly established FCN assay allows measurement of the neutralization activity of chimeric antibodies expressed in cell culture supernatants. Thus, this sensitive and high-throughput FCN assay is a useful alternative to the MN assay for measuring the antibody neutralization of HAdV-3 and for screening anti-HAdV-3 NAbs in cell culture supernatants.

Development of two antigen-binding fragments to a conserved linear epitope of human adenovirus and their application in immunofluorescence.

Detection of human adenoviruses (HAdVs) in nasopharyngeal swab samples by immunofluorescence assay (IFA) will be valuable for diagnosing HAdV infection, which is a leading cause of severe respiratory tract disease, and will help in curbing the spread of HAdV. Monoclonal antibodies employed in IFA for HAdV detection should ideally target highly conserved epitope types. Here, we describe the development of two antigen-binding fragments (Fabs) with specific reactivity to HAdV using phage antibody library technology. When tested with IFA, both Fabs recognized cells infected with several types of HAdV, some of which have been identified in epidemics globally, or associated with outbreaks of severe or fatal acute respiratory diseases. The specificity and cross-reactivity of both Fabs to HAdVs indicated that the generated Fabs could be applied in the development of IFAs to detect HAdVs. Both Fabs bound to the knob proteins, as shown by chemiluminescence enzyme immunoassay and western blot. In addition, epitope mapping showed that both Fabs recognized a conserved linear epitope among several types of HAdV. Two different Fabs recognized the same epitope, suggesting that the epitope triggered the production of at least two kinds of antibodies in the body. The generated Fabs exerted no neutralization against HAdVs. The results demonstrate that both Fabs bind to an epitope that plays no role in neutralization of HAdV.