Characterization of a replication-competent vector encoding DsRed based on a human adenovirus type 4 a-like strain

Human adenovirus type 4 (HAdV-4) associated acute respiratory tract infection in children & genetic characteristics of HAdV-4 in China: a prospective multicenter study

BACKGROUND

Human adenovirus (HAdV) is an important pathogen causing acute respiratory infection (ARI) in children. Many countries, including China, have experienced sporadic or outbreaks related to HAdV-4, and death cases were reported. However, there is little research on HAdV-4 and the epidemic situation of HAdV-4 in China is little known. This study was designed to comprehend the prevalence and genetic characteristics of HAdV-4 in ARI children in China.

METHODS

Respiratory tract samples from ARI children hospitalized in six hospitals of Northern and Southern China from 2017 to 2020 were collected for HAdV detection and typing. Clinical information was collected from HAdV-4 positive patients for clinical characteristics and epidemiological analysis. The main capsid proteins and the whole genome sequences were amplified and sequenced for bioinformatics analysis.

RESULTS

There were 2847 ARI children enrolled, and 156 (5.48%) HAdV positive samples were detected. Eleven HAdV-4 positive samples were identified, accounting for 0.39% of the total samples and 7.05% of the HAdV positive samples. The main manifestations were fever and cough. Two children had conjunctivitis. Two children were diagnosed with severe pneumonia and developed respiratory failure. One of them developed hemophagocytic syndrome and checked in pediatric intensive care unit (PICU). This child had ventricular septal defect. All the children recovered. The isolated strains of HAdV-4 obtained in this study and the reference strains from China located in the same phylogenetic branch (HAdV-4a), while the prototype strain and vaccine strains formed another branch (HAdV-4p). Upon comparison with the prototype strain, there were a few amino acid mutations existing in three major capsid proteins. According to recombination analysis, no new recombination was found.

CONCLUSIONS

The detection rate of HAdV-4 in children hospitalized with ARI was 0.39% in the total samples and 7.05% of all HAdV positive samples. HAdV-4 isolates obtained in this study and other reference strains from China belonged to the HAdV-4a subtype. Our data provided reference for the monitoring, prevention and control of HAdV-4, as well as the research and development of vaccines and drugs.

Viral vectored vaccines: design, development, preventive and therapeutic applications in human diseases

Human diseases, particularly infectious diseases and cancers, pose unprecedented challenges to public health security and the global economy. The development and distribution of novel prophylactic and therapeutic vaccines are the prioritized countermeasures of human disease. Among all vaccine platforms, viral vector vaccines offer distinguished advantages and represent prominent choices for pathogens that have hampered control efforts based on conventional vaccine approaches. Currently, viral vector vaccines remain one of the best strategies for induction of robust humoral and cellular immunity against human diseases. Numerous viruses of different families and origins, including vesicular stomatitis virus, rabies virus, parainfluenza virus, measles virus, Newcastle disease virus, influenza virus, adenovirus and poxvirus, are deemed to be prominent viral vectors that differ in structural characteristics, design strategy, antigen presentation capability, immunogenicity and protective efficacy. This review summarized the overall profile of the design strategies, progress in advance and steps taken to address barriers to the deployment of these viral vector vaccines, simultaneously highlighting their potential for mucosal delivery, therapeutic application in cancer as well as other key aspects concerning the rational application of these viral vector vaccines. Appropriate and accurate technological advances in viral vector vaccines would consolidate their position as a leading approach to accelerate breakthroughs in novel vaccines and facilitate a rapid response to public health emergencies.

Recombinant vesicular stomatitis vaccine against Nipah virus has a favorable safety profile: Model for assessment of live vaccines with neurotropic potential

Nipah virus (NiV) disease is a bat-borne zoonosis responsible for outbreaks with high lethality and is a priority for vaccine development. With funding from the Coalition of Epidemic Preparedness Innovations (CEPI), we are developing a chimeric vaccine (PHV02) composed of recombinant vesicular stomatitis virus (VSV) expressing the envelope glycoproteins of both Ebola virus (EBOV) and NiV. The EBOV glycoprotein (GP) mediates fusion and viral entry and the NiV attachment glycoprotein (G) is a ligand for cell receptors, and stimulates neutralizing antibody, the putative mediator of protection against NiV. PHV02 is identical in construction to the registered Ebola vaccine (Ervebo) with the addition of the NiV G gene. NiV ephrin B2 and B3 receptors are expressed on neural cells and the wild-type NiV is neurotropic and causes encephalitis in affected patients. It was therefore important to assess whether the NiV G alters tropism of the rVSV vector and serves as a virulence factor. PHV02 was fully attenuated in adult hamsters inoculated by the intramuscular (IM) route, whereas parental wild-type VSV was 100% lethal. Two rodent models (mice, hamsters) were infected by the intracerebral (IC) route with graded doses of PHV02. Comparator active controls in various experiments included rVSV-EBOV (representative of Ebola vaccine) and yellow fever (YF) 17DD commercial vaccine. These studies showed PHV02 to be more neurovirulent than both rVSV-EBOV and YF 17DD in infant animals. PHV02 was lethal for adult hamsters inoculated IC but not for adult mice. In contrast YF 17DD retained virulence for adult mice inoculated IC but was not virulent for adult hamsters. Because of the inconsistency of neurovirulence patterns in the rodent models, a monkey neurovirulence test (MNVT) was performed, using YF 17DD as the active comparator because it has a well-established profile of quantifiable microscopic changes in brain centers and a known reporting rate of neurotropic adverse events in humans. In the MNVT PHV02 was significantly less neurovirulent than the YF 17DD vaccine reference control, indicating that the vaccine will have an acceptable safety profile for humans. The findings are important because they illustrate the complexities of phenotypic assessment of novel viral vectors with tissue tropisms determined by transgenic proteins, and because it is unprecedented to use a heterologous comparator virus (YF vaccine) in a regulatory-enabling study. This approach may have value in future studies of other novel viral vectors.

Rescue of Recombinant Adenoviruses by CRISPR/Cas-Mediated in vivo Terminal Resolution

Recombinant adenovirus (rAd) vectors represent one of the most frequently used vehicles for gene transfer applications in vitro and in vivo. rAd genomes are constructed in Escherichia coli where their genomes can be maintained, propagated, and modified in form of circular plasmids or bacterial artificial chromosomes. Although the rescue of rAds from their circular plasmid or bacmid forms is well established, it works with relatively low primary efficiency, preventing this technology for library applications. To overcome this barrier, we tested a novel strategy for the reconstitution of rAds that utilizes the CRISPR/Cas-machinery to cleave the circular rAd genomes in close proximity to their inverted terminal repeats (ITRs) within the producer cells upon transfection. This CRISPR/Cas-mediated in vivo terminal resolution allowed efficient rescue of vectors derived from different human adenovirus (HAdV) species. By this means, it was not only possible to increase the efficiency of virus rescue by about 50-fold, but the presented methodology appeared also remarkably simpler and faster than traditional rAd reconstitution methods.

Outbreaks of Adenovirus-associated Respiratory Illness on 5 College Campuses in the United States, 2018-2019

BACKGROUND

Human adenoviruses (HAdVs) are commonly associated with acute respiratory illness. HAdV outbreaks are well documented in congregate military training settings, but less is known about outbreaks on college campuses. During fall 2018 and spring 2019, 5 United States (US) colleges reported increases in HAdV-associated respiratory illness. Investigations were performed to better understand HAdV epidemiology in this setting.

METHODS

A case was defined as a student at one of the 5 colleges, with acute respiratory illness and laboratory-confirmed HAdV infection during October 2018-December 2018 or March-May 2019. Available respiratory specimens were typed by HAdV type-specific real-time polymerase chain reaction assays, and for a subset, whole genome sequencing was performed. We reviewed available medical records and cases were invited to complete a questionnaire, which included questions on symptom presentation, social history, and absenteeism.

RESULTS

We identified 168 HAdV cases. Median age was 19 (range, 17-22) years and 102 cases (61%) were male. Eleven cases were hospitalized, 10 with pneumonia; 2 cases died. Among questionnaire respondents, 80% (75/94) missed ≥ 1 day of class because of their illness. Among those with a type identified (79%), HAdV types 4 and 7 were equally detected, with frequency of each varying by site. Genome types 4a1 and 7d were identified, respectively, by whole genome sequence analysis.

CONCLUSIONS

HAdV respiratory illness was associated with substantial morbidity and missed class time among young, generally healthy adults on 5 US college campuses. HAdVs should be considered a cause of respiratory illness outbreaks in congregate settings such as college campuses.

Seroprevalence of Neutralizing Antibodies against Six Human Adenovirus Types Indicates the Low Level of Herd Immunity in Young Children from Guangzhou, China

Human adenoviruses (HAdVs) commonly cause many diseases such as respiratory diseases, gastroenteritis, cystitis worldwide. HAdV-3, -7, -4 and emergent HAdV-55 and HAdV-14 are the most important types causing severe respiratory diseases. There is no effective drug available for clinical treatment, and no vaccine available for the general population. Therefore, it is important to investigate the seroprevalence against HAdV for developing novel vaccines and vectors. In this study, we investigated the seroprevalence and titer levels of neutralizing antibodies (NAb) against HAdV-3, -4, -7, -14, -55, and -11 in total 278 healthy populations between 0 months and 49 years of age (228 children and 50 adults) from Guangzhou. In children under the age of 18 years, the seropositive rates were significantly increased against HAdV-3 at 12.07%, 33.96%, and 64.29% and against HAdV-7 at 0%, 18.87%, and 19.05% in age groups of 1–2, 3–5, and 6–17 years, respectively. The seroprevalence was very low (0% ~ 8.1%) for all other four types. In adults aged between 18 and 49 years, HAdV-3, -4, and -7 (> 50.00%) were the most common types, followed by HAdV-14 (38.00%), -55 (34.00%), and -11 (24.00%). Adults tended to have high NAb titers against HAdV-4 and -55. HAdV-55-seropositive donors tended to be HAdV-11- and HAdV-14-seropositive. These results indicated the low level of herd immunity against all six HAdV types in young children, and HAdV-14, -55, -11 in adults from Guangzhou City. Our findings demonstrate the importance of monitoring HAdV types and developing vaccines against HAdV for children and adults.