Human parainfluenza virus type 3 (HPIV-3): construction and rescue of an infectious, recombinant virus expressing the enhanced green fluorescent protein (EGFP)

Safety of inoculation of bovine parainfluenza virus 3 as potential vaccine vector in pigs

Bovine parainfluenza virus 3 (BPIV3) is one of the most important respiratory pathogens in cattle. One BPIV3, named NM09, was isolated from cattle suffering from severe respiratory diseases in 2009. BPIV3 is a potential recombinant vaccine vector. To investigate whether NM09 can infect pigs and determine BPIV3 defense in these animals, BPIV3 antibody-free pigs were inoculated intramuscularly with the BPIV3 NM09 strain in a continuous passage. Clinical signs were observed each day after inoculation. Viral nucleic acid was detected in nasal and anal secretions. Results showed that virus-inoculated pigs displayed few observable clinical signs related to respiratory diseases. The antibody was identified, but the virus could not be detected in the second continuous passage in pigs. Thus, BPIV3 is a potential vaccine vector for genetic engineering.

Deletion of the D domain of the human parainfluenza virus type 3 (HPIV3) PD protein results in decreased viral RNA synthesis and beta interferon (IFN-β) expression

The human parainfluenza virus type 3 (HPIV3) phosphoprotein (P) gene is unusual as it contains an editing site where nontemplated ribonucleotide residues can be inserted. This RNA editing can lead to the expression of the viral P, PD, putative W, and theoretical V protein from a single gene. Although the HPIV3 PD protein has been detected, its function and those of the W and V proteins are poorly understood. Therefore, we first used reverse genetics techniques to construct and rescue a recombinant (r)HPIV3 clone with a polyhistidine sequence at the 5' end of the P gene for tagged protein detection. Western blot analysis demonstrated the presence of the P, PD, and W proteins, but no V protein was detected. Then, we functionally studied the D domain of the PD protein by constructing two rHPIV3 knockout clones that are deficient in the expression of the D domain. Results from growth kinetic studies with infected MA-104 and A596 cells showed that viral replication of the two knockout viruses (rHPIV3-ΔES and rHPIV3-ΔD) was comparable to that of the parental virus in both cell lines. However, viral mRNA transcription and genomic replication was significantly reduced. Furthermore, cytokine/chemokine profiles of A549 cells infected with either knockout virus were unchanged or showed lower levels compared to those from cells infected with the parental virus. These data suggest that the D domain of the PD protein may play a luxury role in HPIV3 RNA synthesis and may also be involved in disrupting the expression of beta interferon.

Oncolytic bluetongue viruses: promise, progress, and perspectives

Humans are sero-negative toward bluetongue viruses (BTVs) since BTVs do not infect normal human cells. Infection and selective degradation of several human cancer cell lines but not normal ones by five US BTV serotypes have been investigated. We determined the susceptibilities of many normal and human cancer cells to BTV infections and made comparative kinetic analyses of their cytopathic effects, survival rates, ultra-structural changes, cellular apoptosis and necrosis, cell cycle arrest, cytokine profiles, viral genome, mRNAs, and progeny titers. The wild-type US BTVs, without any genetic modifications, could preferentially infect and degrade several types of human cancer cells but not normal cells. Their selective and preferential BTV-degradation of human cancer cells is viral dose–dependent, leading to effective viral replication, and induced apoptosis. Xenograft tumors in mice were substantially reduced by a single intratumoral BTV injection in initial in vivo experiments. Thus, wild-type BTVs, without genetic modifications, have oncolytic potentials. They represent an attractive, next generation of oncolytic viral approach for potential human cancer therapy combined with current anti-cancer agents and irradiation.