A novel live attenuated vaccine candidate protects chickens against subtype B avian metapneumovirus

Avian metapneumovirus(aMPV) is a highly contagious pathogen that causes acute upper respiratory tract diseases in chickens and turkeys, resulting in serious economic losses. Subtype B aMPV has recently become the dominant epidemic strain in China. We developed an attenuated aMPV subtype B strain by serial passaging in Vero cells and evaluated its safety and efficacy as a vaccine candidate. The safety test showed that after the 30th passage, the LN16-A strain was fully attenuated, as clinical signs of infection and histological lesions were absent after inoculation.The LN16-A strain did not revert to a virulent strain after five serial passages in chickens. The genomic sequence of LN16-A differed from that of the parent wild-type LN16(wtLN16) strain and had nine amino acid mutations. In chickens, a single immunization with LN16-A induced robust humoral and cellular immune responses, including the abundant production of neutralizing antibodies, CD4^(+) T lymphocytes, and the Th1(IFN-γ) and Th2(IL-4 and IL-6)cytokines. We also confirmed that LN16-A provided 100% protection against subtype B aMPV and significantly reduced viral shedding and turbinate inflammation. Our findings suggest that the LN16-A strain is a promising live attenuated vaccine candidate that can prevent infection with subtype B aMPV.

Serosurvey of Avian metapneumovirus, Orithobacterium rhinotracheale, and Chlamydia psittaci and Their Potential Association with Avian Airsacculitis

Seasonal outbreaks of airsacculitis in China＇s poultry cause great economic losses annually. This study tried to unveil the potential role of Avian metopneumovirus （AM PV）, Ornithobacterium rhinotrocheale （aRT） and Chlarnydia psittaci （CPS） in avian airsacculitis. A serological investigation of 673 breeder chickens and a case-controlled study of 430 birds were undertaken. Results showed that infection with AMPV, aRT, and CPS was highly associated with the disease. The correlation between AMPV and CPS were positively robust in both layers and broilers. Finally, we determined the co-infection with AMPV, aRT, and CPS was prevalent in the sampled poultry farms suffering from respiratory diseases and the outbreak of airsacculitis was closely related to simultaneous exposure to all three agents.

Outbreak of Human Metapneumovirus in Ibaraki, Japan and Its Descriptive Epidemiology

Introduction: The Infection Control Law in Japan does not cover monitoring of human metapneumovirus (HMPV). Therefore, its epidemiology is not well known. However, rapid diagnostic testing for this virus has been reimbursed by public health insurance in Japan since 2014. One case of acute encephalitis caused by HMPV was reported in April 2017 in Ibaraki. All schools in Ibaraki prefecture started to participate in the (Nursery) School Absenteeism Surveillance System ((N)SASSy) in 2009. All nursery schools started to use it in 2012. Methods: We specifically examine its seasonality and incidence by age. The study period extends from October 1, 2014 through May 31, 2017. Results: In total, (N)SASSy received 187 cases during the period. Spring and early summer were apparently the high season. The highest incidence was 36 cases in April 2015. The incidence among zero and one year olds was higher in 2017 than in the same season among 2014-2016. The necessary effort to download data from (N)SASSy, show these figures, and confirm the situation and background was a few minutes. Discussion: Rapid diagnostic testing for HMPV elucidated its epidemiology for the first time. Moreover, timely information sharing through (N)SASSy led the Ibaraki prefectural office to publish a reminder in July 2017 about the HMPV outbreak situation and to encourage precautions against it by nursery schools.

The Prevalence of Human Metapneumovirus among Children with Acute Respiratory Tract Infection in North Kordofan State, Sudan

Objective: To determine the prevalence of human metapneumovirus (hMPV) among children with acute respiratory tract infection and the correlation between (hMPV) and age group. Methods: This prospective, descriptive cross-sectional hospital-based study is carried out from January to May 2019 among children from under five years old who were admitted to El-Obeid pediatric teaching Hospital, North kordofan, Sudan with acute respiratory tract infection. Results: Fifty hospitalized children with acute respiratory tract infection were enrolled in the study. Two of these (4%) were tested positive for (hMPV) in the age group (7 months - 2 years) old. Moreover, the study showed no significant correlation between infection with (hMPV) and age.

Characterization of human metapneumovirus from pediatric patients with acute respiratory infections in a 4-year period in Beijing, China

Background Human metapneumovirus （hMPV） was discovered by scientists in the Netherlands as a novel respiratory virus in 2001 and had been found in children with acute respiratory tract infections （ARTI） in China. The objective of this study was to determine the importance of hMPV infection in children in Beijing and the genotypes of the circulating virus by the surveillance during a four-consecutive-year period.

Clinical characteristics and molecular epidemiology of human metapneumovirus in children with acute lower respiratory tract infections in China, 2017 to 2019: A multicentre prospective observational study

Human metapneumovirus(HMPV) infection is one of the leading causes of hospitalization in young children with acute respiratory illness. In this study, we prospectively collected respiratory tract samples from children who were hospitalized with acute lower respiratory tract infection in six hospitals in China from 2017 to 2019. HMPV was detected in 145 out of 2733 samples(5.3%) from the hospitalized children. The majority of HMPV-positive children were under the age of two(67.6%), with a median age of one year. HMPV can independently cause acute lower respiratory tract infection in young children, while all patients showed mild clinical symptoms. Of all the co-infected patients, HMPV was most commonly detected with enterovirus(EV) or rhinovirus(RhV)(38.0%),followed by respiratory syncytial virus(RSV)(32.0%). The highest detection rate occurred from March to May in both northern and southern China. Out of 145 HMPV positive samples, 48 were successfully typed, of which 36strains were subgrouped into subtypes A2c(75%), eight strains were included in subtype B1(16.7%), and four strains were included in subtype B2(8.3%). Moreover, 16 A2c strains contained 111-nucleotide duplications in the G gene. Twenty-seven complete HMPV genomes were successfully obtained, and 25(92.6%) strains belonged to subtype A2c, whereas one strain was included in subgroup B1 and another was included in subgroup B2. A total of 277 mutations were observed in the complete genomes of 25 A2c strains. All results presented here improve our understanding of clinical characteristics and molecular epidemiology of HMPV infection in children.

Characterization of human metapneumoviruses isolated in Chongqing, China

Background Human metapneumovirus （hMPV） has recently been recognized as a notable respiratory pathogen in children. However, no isolation processes and only a limited understanding of hMPV epidemiology present in Chinese children are documented by far. Methods Nasopharyngeal aspirates from 86 hospitalized children with acute respiratory tract infections from December 2004 to July 2005 were inoculated onto Vero-E6 cells for hMPV isolation. Total RNA was extracted from infected cells with a cytopathic effect and then subjected to a RT-PCR amplification of the N and F genes of the hMPV. Nucleotide sequences of amplified F gene products were examined using a variation analysis with the MegAlign program and the phylogenetic tree construction using the neighbor-joining algorithm with a Phylip package. Results Six strains of hMPV were isolated from the samples during winter, spring and summer. The most common symptoms were coughing and cyanosis, and the diagnoses were bronchiolitis, bronchopneumonia, infantile asthma, or upper respiratory tract infection. All isolates were in the A2 genetic sublineage and shared a high percentage of homology with the F gene in the nucleotide （99.8%--100%） and amino acid （99.3%--100%） sequences. Conclusions This report indicates that hMPV is an important viral agent for acute respiratory tract infections present in Chongqing, China. Knowledge of phylogeny and genes will benefit the studies on the treatment and prophylaxis of hMPV infection.

In vitro and in vivo anti-HMPV activity of JH001 isolated from Chinese medicinal herbs

OBJECTIVE Human metapneumovirus(hMPV)is semblable to respiratory syncytial virus(RSV)which causes respiratory infections typically characterized by cough,runny nose,fever,and nasal congestion but sometimes progressing to bronchiolitis and pneumonia.Whereas,there is no corresponding drug to inhabit the virus.Studies of new compounds with potential anti-HMPV activity could produce clinical value.Chinese herbal medicine played a great role during COVID-19,therefore we choose some small molecular(JH001)extracted from botany to investigate therapeutic effect on hMPV and the underlying mechanisms.METHODS In this study,16HBE cells were used as a model to explore in vitro antiviral effect.Cytotoxicity assays were performed before the antiviral tests,cell viability of 16HBE cells handled by different concentration of JH001 was estimated by Cell Counting Kit-8(CCK-8).Then RT-qPCR,immunofluorescence,and flow cytometer were used to test the viral titer after cells infected with hMPV.Eventually,6-8 weeks mice were infected intranasally with 60μL of hMPV,the control group was treated with 0.9%saline water,other groups were administered with JH001 and ribavirin,then the lung virus titer and protective effect in lung were judged.RESULTS The obtained JH001 exhibited no cytotoxicity to 16HBE cells during 6.25-200μmol·L^(-1).RT-QPCR demonstrated that JH001 showed obvious inhabitation to the viral replication and showed great significance compared with saline.And fluorescence exhibited distinct decrease of hMPV-N protein,flow cytometer results showed that MFI decrease evidently.Significant reduction of N-gene expression was observed in those mice treated with JH001 compared with saline group,which indicated that JH001 probably had protective and therapeutic effect on viral replication.CONCLUSION This study illustrated that JH001 might be a promising option for small molecular against hMPV and JH001 might be worthy of further development and used as a potential therapeutic strategy for other respiratory viruses in the future.

从呼吸道标本中分离人偏肺病毒及病毒培养方法比较

目的从急性呼吸道感染患者的鼻咽拭子标本中分离人偏肺病毒(hMPV),同时利用分离株比较3种病毒培养方法,探索适合于临床病毒实验室分离培养hMPV的方法。方法接种55份经实时荧光定量PCR(real time-PCR)法检测为hMPV阳性的鼻咽拭子标本至Vero-E6细胞,连续盲传培养3代。每天观察细胞病变,结合real time-PCR和直接免疫荧光法(DFA)检测病毒的核酸复制和蛋白抗原,对分离株的G和F基因序列进行同源性分析。利用real time-PCR比较转鼓培养法、离心培养法和静置培养法3种方法hMPV的复制效率。结果从55份临床标本中分离鉴定出3株hMPV病毒(GZ/1/12、GZ/2/12、GZ/3/12),序列同源性分析显示3株临床分离株属于B型。hMPV病毒复制效率比较:转鼓培养法与离心培养法对hMPV复制效率相当,二者皆优于静置培养法。而离心培养法的操作更简便,更适用临床病毒实验室。结论成功分离鉴定出3株hMPV临床株,离心培养法更适合临床病毒实验室分离培养hMPV。