A novel human parainfluenza virus type 1 (HPIV1) with separated P and C genes is useful for generating C gene mutants for evaluation as live-attenuated virus vaccine candidates

Tailam paramyxovirus C protein inhibits viral replication

Jeilongviruses are emerging single-stranded negative-sense RNA viruses in the Paramyxoviridae family. Tailam paramyxovirus (TlmPV) is a Jeilongvirus that was identified in 2011. Very little is known about the mechanisms that regulate viral replication in these newly emerging viruses. Among the non-structural viral proteins of TlmPV, the C protein is predicted to be translated from an open reading frame within the phosphoprotein gene through alternative translation initiation. Though the regulatory roles of C proteins in virus replication of other paramyxoviruses have been reported before, the function of the TlmPV C protein and the relevant molecular mechanisms have not been reported. Here, we show that the C protein is expressed in TlmPV-infected cells and negatively modulates viral RNA replication. The TlmPV C protein interacts with the P protein, negatively impacting the interaction between N and P, resulting in inhibition of viral RNA replication. Deletion mutagenesis studies indicate that the 50 amino-terminal amino acid residues of the C protein are dispensable for its inhibition of virus RNA replication and interaction with the P protein.IMPORTANCETailam paramyxovirus (TlmPV) is a newly identified paramyxovirus belonging to the Jeilongvirus genus, of which little is known. In this work, we confirmed the expression of the C protein in TlmPV-infected cells, assessed its function, and defined a potential mechanism of action. This is the first time that the existence of a Jeilongvirus C protein has been confirmed and its role in viral replication has been reported.

Review detection of Newcastle disease virus

Newcastle disease (ND) is an acute and highly contagious disease caused by the Newcastle disease virus (NDV) infecting poultry, which has caused great harm to the poultry industry around the world. Rapid diagnosis of NDV is important to early treatment and early institution of control measures. In this review, we comprehensively summarize the most recent research into NDV, including historical overview, molecular structure, and infection mechanism. We then focus on detection strategies for NDV, including virus isolation, serological assays (such as hemagglutination and hemagglutination-inhibition tests, enzyme linked immunosorbent assay, reporter virus neutralization test, Immunofluorescence assay, and Immune colloidal gold technique), molecular assays (such as reverse transcription polymerase chain reaction, real-time quantitative PCR, and loop-mediated isothermal amplification) and other assays. The performance of the different serological and molecular biology assays currently available was also analyzed. To conclude, we examine the limitations of currently available strategies for the detection of NDV to lay the groundwork for new detection assays.

Type I and Type II Interferon Antagonism Strategies Used by Paramyxoviridae: Previous and New Discoveries, in Comparison

Paramyxoviridae is a viral family within the order of Mononegavirales; they are negative single-strand RNA viruses that can cause significant diseases in both humans and animals. In order to replicate, paramyxoviruses–as any other viruses–have to bypass an important protective mechanism developed by the host’s cells: the defensive line driven by interferon. Once the viruses are recognized, the cells start the production of type I and type III interferons, which leads to the activation of hundreds of genes, many of which encode proteins with the specific function to reduce viral replication. Type II interferon is produced by active immune cells through a different signaling pathway, and activates a diverse range of genes with the same objective to block viral replication. As a result of this selective pressure, viruses have evolved different strategies to avoid the defensive function of interferons. The strategies employed by the different viral species to fight the interferon system include a number of sophisticated mechanisms. Here we analyzed the current status of the various strategies used by paramyxoviruses to subvert type I, II, and III interferon responses.

C Proteins: Controllers of Orderly Paramyxovirus Replication and of the Innate Immune Response

Particles of many paramyxoviruses include small amounts of proteins with a molecular weight of about 20 kDa. These proteins, termed “C”, are basic, have low amino acid homology and some secondary structure conservation. C proteins are encoded in alternative reading frames of the phosphoprotein gene. Some viruses express nested sets of C proteins that exert their functions in different locations: In the nucleus, they interfere with cellular transcription factors that elicit innate immune responses; in the cytoplasm, they associate with viral ribonucleocapsids and control polymerase processivity and orderly replication, thereby minimizing the activation of innate immunity. In addition, certain C proteins can directly bind to, and interfere with the function of, several cytoplasmic proteins required for interferon induction, interferon signaling and inflammation. Some C proteins are also required for efficient virus particle assembly and budding. C-deficient viruses can be grown in certain transformed cell lines but are not pathogenic in natural hosts. C proteins affect the same host functions as other phosphoprotein gene-encoded proteins named V but use different strategies for this purpose. Multiple independent systems to counteract host defenses may ensure efficient immune evasion and facilitate virus adaptation to new hosts and tissue environments.

Attenuated Human Parainfluenza Virus Type 1 (HPIV1) Expressing the Fusion Glycoprotein of Human Respiratory Syncytial Virus (RSV) as a Bivalent HPIV1/RSV Vaccine

Live attenuated recombinant human parainfluenza virus type 1 (rHPIV1) was investigated as a vector to express the respiratory syncytial virus (RSV) fusion (F) glycoprotein, to provide a bivalent vaccine against RSV and HPIV1. The RSV F gene was engineered to include HPIV1 transcription signals and inserted individually into three gene locations in each of the two attenuated rHPIV1 backbones. Each backbone contained a single previously described attenuating mutation that was stabilized against deattenuation, specifically, a non-temperature-sensitive deletion mutation involving 6 nucleotides in the overlapping P/C open reading frames (ORFs) (C(Δ170)) or a temperature-sensitive missense mutation in the L ORF (L(Y942A)). The insertion sites in the genome were pre-N (F1), N-P (F2), or P-M (F3) and were identical for both backbones. In vitro, the presence of the F insert reduced the rate of virus replication, but the final titers were the same as the final titer of wild-type (wt) HPIV1. High levels of RSV F expression in cultured cells were observed with rHPIV1-C(Δ170)-F1, -F2, and -F3 and rHPIV1-L(Y942A)-F1. In hamsters, the rHPIV1-C(Δ170)-F1, -F2, and -F3 vectors were moderately restricted in the nasal turbinates, highly restricted in lungs, and genetically stable in vivo. Among the C(Δ170) vectors, the F1 virus was the most immunogenic and protective against wt RSV challenge. The rHPIV1-L(Y942A) vectors were highly restricted in vivo and were not detectably immunogenic or protective, indicative of overattenuation. The C(Δ170)-F1 construct appears to be suitably attenuated and immunogenic for further development as a bivalent intranasal pediatric vaccine.

IMPORTANCE

There are no vaccines for the pediatric respiratory pathogens RSV and HPIV. We are developing live attenuated RSV and HPIV vaccines for use in virus-naive infants. Live attenuated RSV strains in particular are difficult to develop due to their poor growth and physical instability, but these obstacles could be avoided by the use of a vaccine vector. We describe the development and preclinical evaluation of live attenuated rHPIV1 vectors expressing the RSV F protein. Two different attenuated rHPIV1 backbones were each engineered to express RSV F from three different gene positions. The rHPIV1-C(Δ170)-F1 vector, bearing an attenuating deletion mutation (C(Δ170)) in the P/C gene and expressing RSV F from the pre-N position, was attenuated, stable, and immunogenic against the RSV F protein and HPIV1 in the hamster model and provided substantial protection against RSV challenge. This study provides a candidate rHPIV1-RSV-F vaccine virus suitable for continued development as a bivalent vaccine against two major childhood pathogens.

Human parainfluenza virus serotypes differ in their kinetics of replication and cytokine secretion in human tracheobronchial airway epithelium

Human parainfluenza viruses (PIVs) cause acute respiratory illness in children, the elderly, and immunocompromised patients. PIV3 is a common cause of bronchiolitis and pneumonia, whereas PIV1 and 2 are frequent causes of upper respiratory tract illness and croup. To assess how PIV1, 2, and 3 differ with regard to replication and induction of type I interferons, interleukin-6, and relevant chemokines, we infected primary human airway epithelium (HAE) cultures from the same tissue donors and examined replication kinetics and cytokine secretion. PIV1 replicated to high titer yet did not induce cytokine secretion until late in infection, while PIV2 replicated less efficiently but induced an early cytokine peak. PIV3 replicated to high titer but induced a slower rise in cytokine secretion. The T cell chemoattractants CXCL10 and CXCL11 were the most abundant chemokines induced. Differences in replication and cytokine secretion might explain some of the differences in PIV serotype-specific pathogenesis and epidemiology.

Progress in the development of human parainfluenza virus vaccines

In children under 5 years of age, human parainfluenza viruses (HPIVs) as a group are the second most common etiology of acute respiratory illness leading to hospitalization, surpassed only by respiratory syncytial virus but ahead of influenza viruses. Using reverse genetics systems for HPIV serotypes 1, 2 and 3 (HPIV1, 2 and 3), several live-attenuated HPIVs have been generated and evaluated as intranasal vaccines in adults and in children. Two vaccines against HPIV3 were found to be well tolerated, infectious and immunogenic in Phase I trials in HPIV3-seronegative infants and children and should progress to proof-of-concept trials. Vaccines against HPIV1 and HPIV2 are less advanced and have just entered pediatric trials.