Vaccines for the Paramyxoviruses and Pneumoviruses: Successes, Candidates, and Hurdles.

Human parainfluenza viruses (family Paramyxoviridae), human metapneumovirus, and respiratory syncytial virus (family Pneumoviridae) infect most infants and children within the first few years of life and are the etiologic agents for many serious acute respiratory illnesses. These virus infections are also associated with long-term diseases that impact quality of life, including asthma. Despite over a half-century of vaccine research, development, and clinical trials, no vaccine has been licensed to date for the paramyxoviruses or pneumoviruses for the youngest infants. In this study, we describe the recent reclassification of paramyxoviruses and pneumoviruses into distinct families by the International Committee on the Taxonomy of Viruses. We also discuss some past unsuccessful vaccine trials and some currently preferred vaccine strategies. Finally, we discuss hurdles that must be overcome to support successful respiratory virus vaccine development for the youngest children.

Current developments and prospects on human metapneumovirus vaccines.

INTRODUCTION: Human metapneumovirus (hMPV) has become one of the major pathogens causing acute respiratory infections (ARI) mainly affecting young children, immunocompromised patients, and the elderly. Currently there are no licensed vaccines against this virus. Areas covered: Since the discovery of hMPV in 2001, many groups have focused on developing vaccines against this pathogen. This review presents the outcomes and perspectives derived from preclinical studies performed in cell cultures and animals as well as the only candidate that has reached evaluation in a clinical trial. Limitations of the current vaccine candidates are discussed and perspectives for the development of plant-based vaccines are analyzed. Expert commentary: Several hMPV vaccine candidates are under development with the potential to progress into clinical trials. In parallel, the molecular farming field offers new opportunities to generate innovative vaccines that will offer several advantages in the fight against hMPV.

Evaluation of attenuation, immunogenicity and efficacy of a bovine parainfluenza virus type 3 (PIV-3) vaccine and a recombinant chimeric bovine/human PIV-3 vaccine vector in rhesus monkeys.

Restricted replication in the respiratory tract of rhesus monkeys is an intrinsic property of bovine parainfluenza virus type 3 (bPIV-3) strains. This host range phenotype of bPIV-3 has been utilized as a marker to evaluate the attenuation of bPIV-3 vaccines for human use. Two safety, immunogenicity and efficacy studies in primates evaluated and compared three human parainfluenza virus type 3 (hPIV-3) vaccine candidates: biologically derived bPIV-3, a plasmid-derived bPIV-3 (r-bPIV-3) and a chimeric bovine/human PIV-3 (b/hPIV-3). These studies also examined the feasibility of substituting Vero cells, cultured in the presence or absence of foetal bovine serum, for foetal rhesus lung-2 (FRhL-2) cells as the tissue culture substrate for the production of bPIV-3 vaccine. The results demonstrated that (i) Vero cell-produced bPIV-3 was as attenuated, immunogenic and efficacious as bPIV-3 vaccine grown in FRhL-2 cells, (ii) plasmid-derived bPIV-3 was as attenuated, immunogenic and efficacious as the biologically derived bPIV-3 and (iii) the b/hPIV-3 chimera displayed an intermediate attenuation phenotype and protected animals completely from hPIV-3 challenge. These results support the use of bPIV-3 vaccines propagated in Vero cells in human clinical trials and the use of b/hPIV-3 as a virus vaccine vector to express foreign viral antigens.

Enhanced resistance to Sendai virus infection in DBA/2J mice with a botanical drug combination (Sinupret).

It was investigated whether the botanical drug combination Sinupret is able to modulate the resistance of mice to a respiratory tract infection with Sendai virus (Parainfluenza viridae) if given prophylactically to the animals. Three doses of Sinupret drops (SD) and Sinupret tablets (ST, p.o.), and two active controls, the chemical secretolytic ambroxol (p.o.) and the immunomodulator Muramyldipeptide (MDP, i.v.) were used. Test and reference substances were applied at days - 3 and -1 before infection, except MDP, which was given once on day--before infection. CD4+ and CD8 + lymphocyte subpopulations were measured after infection as indicators of immunological treatment response. Groups of 20 mice each were infected by intranasal application of Sendai virus under anaesthesia. We found that the 1 x and 5 x human doses of Sinupret drops significantly prolonged the survival times (p < 0.05) compared to placebo. Additionally, ambroxol and MDP were comparably less effective. In all groups, changes in CD4 + and CD8 + T-lymphocyte subpopulations of the peripheral blood were observed, but no clear relationship to the treatment results was seen. It was concluded that Sinupret increases the resistance to an experimentally induced respiratory tract infection in mice. Moreover, the effect of Sinupret was superior to that of an immunostimulant (MDP) and of a synthetic secretagogue (ambroxolhydrochloride).

[The use of gamma-interferon for the prevention and treatment of infectious diseases in piglets and calves]. / Vykorystannia hamma-interferonu dlia profilaktyky ta likuvannia infektsiinykh khvorob porosiat i teliat.

Administration of the homologous natural gamma-interferon for prophylaxis of infectious diseases showed that 2-3 injections of gamma-interferon prevented infectious morbidity of more than 90% of sucking pigs and new-born calves, sharply increased their preservation to 90% and above, increased their productivity by 1/3. In conditions of industrial growing of young animals therapy by this preparation of pigs and calves with colibacteriosis and parainfluenza in comparison with control significantly decreased mortality of morbid young animals, accelerated their recovery and promoted the weight gain in pigs and calves.

Treatment and prophylaxis of some infectious diseases of swine and cattle using of natural alpha-interferons.

On the basis of experimental studies which proved stimulating action on absorbing and bactericidal function of blood phagocytes and antibody genesis the methods of therapy and prophylaxis of wide spread infections in modern live-stock (transmissive gastroenteritis of pigs, parainfluenza of calves, colibacteriosis of swine and cattle) were created. It was established, that optimal one-time therapeutical dose of homologous alpha-IFN for intramuscular administration to new-born pigs was 2000-4000 IU per head, prophylactic dose was 1000-2000 IU. Therapeutical doses of alpha-IFN for calves did not exceed 4000-6000 IU, prophylactic--4000 IU. As a rule, it is necessary to introduce the preparation three times with 48 h intervals. With the account of these data the large-scale commissional trials of these preparations were carried out.

Subverting lymph node trafficking by treatment with the Mel-14 monoclonal antibody to L-selectin does not prevent an effective host response to Sendai virus.

A single 250-micrograms dose of the Mel-14 mAb to L-selectin greatly diminished the extent of L-selectin expression on lymphocytes and decreased (60 to 90%) the massive cellular recruitment to the cervical and mediastinal lymph nodes that follows intranasal infection of naive C57BL/6 mice with Sendai virus. The numbers of CD8+ CTL precursors in the mediastinal lymph nodes were considerably reduced on day 7, when compared with virus-infected mice given a control rat IgG2a, but potent CTL effectors were present in the lungs of both groups by day 10 after infection, and the overall magnitude of CTL precursor generation was not obviously compromised. The early dominance of Sendai virus-specific IgM Ab-forming cells was prolonged in the Mel-14-treated mice, whereas plasma cells producing virus-specific IgA were abnormally prominent in the lymph nodes but not in the spleen. The kinetics of virus-specific Ab-forming cells generation and the serum Ab response for the various IgG isotypes were also delayed. Thus, though L-selectin is clearly important for the localization of naive lymphocytes to regional lymph nodes, the Mel-14-treated mouse can still deal effectively with a virus that causes productive infection only in the respiratory tract. The spleen, where L-selectin does not determine lymphocyte trafficking, is a major site for the compensatory T cell and B cell responses.

The antiviral activity of SP-303, a natural polyphenolic polymer, against respiratory syncytial and parainfluenza type 3 viruses in cotton rats.

SP-303, a naturally occurring polyphenolic polymer (average M.W. = 2100 Da), was tested in cotton rats (Sigmoden hispidus) for antiviral activity against respiratory syncytial (RSV) and parainfluenza type 3 (PIV3) viruses, and for acute toxicity. Significant reductions in pulmonary RSV titers, compared to pulmonary RSV titers in comparably treated control animals, were seen in cotton rats given 1-10 mg SP-303/kg/day intraperitoneally (i.p.) on days 1 through to 3, after experimental inoculation with RSV. The minimum efficacious dose of SP-303 against PIV3, when given i.p. for 3 days, was 3 mg/kg/day. Higher doses of SP-303 could not be given i.p., as doses > or = 30 mg/kg/day given once daily by this route for 3 or more consecutive days caused both significant weight loss and death in infected or uninfected animals. Although no toxicity was observed following oral administration of up to 270 mg of SP-303 daily for 3 days, this compound had variable antiviral activity when given by this route.

Evaluation of the immunogenicity and protective efficacy of a candidate parainfluenza virus type 3 subunit vaccine in cotton rats.

A parainfluenza virus type 3 (PIV3) subunit vaccine consisting of detergent-solubilized, affinity-purified haemagglutinin-neuraminidase (HN) and fusion (F) surface glycoproteins was tested in cotton rats for immunogenicity, short-term effects on virus-induced immunopathology and protective efficacy. Groups of animals were immunized twice, 4 weeks apart, with graded doses of vaccine administered either alone or with aluminium phosphate (AlPO4). The minimum immunogenic dose of vaccine was 0.1 microgram HN and F when the vaccine was given alone and 0.01 microgram when the vaccine was administered with AlPO4 adjuvant. Antibody responses in animals immunized with 1 microgram HN and F mixed with adjuvant were similar to those in control animals infected with live PIV3 intranasally. Pulmonary and nasal wash PIV3 titres generally were inversely correlated with serum antibody levels. Virus titres were significantly reduced in all groups of animals immunized with greater than or equal to 0.1 microgram HN and F compared with control animals immunized with vehicle only. Four days after virus challenge, there was no evidence of enhanced histopathology in lung sections from animals immunized with the candidate vaccine.

Prophylactic activity of dihydroheptaprenol, a synthetic polyprenol derivative, against Sendai virus infection in mice.

The effect of a chemically synthesized polyprenol derivative, dihydroheptaprenol (DHP), on the non-specific resistance of mice to Sendai virus infection was investigated. The mice that received 200 micrograms of DHP intranasally twice, at 3 days and 1 day before the infection, showed a significant protection against Sendai virus infection. Treatment of mice twice even with as much as 2000 micrograms of DHP through the subcutaneous route, however, had no protective effect against infection. Excess interferon and tumour necrosis factor production in intranasally DHP-treated mice was seen 1 day after the infection when compared with Sendai virus alone controls or with DHP alone controls. Variance analysis of these findings indicates a prophylactic activity of DHP in pulmonary viral infections.

Vaccination against parainfluenza 1 virus (typus muris) infection in order to eradicate this virus in colonies of laboratory animals.

Parainfluenza 1 virus (typus muris), commonly known as Sendai virus, is still contaminating mouse colonies in Japan. This presents a serious problem to keep mouse colonies pathogen-free. It seems that the infection is spread by dust and the virus remains active a considerable time in the mouse breeding rooms after all mice are removed. In order to eradicate the infection of this virus, vaccination was attempted to inoculate newly born young mice successively for about six months and during and after these periods the movements of the infection were under observation. The vaccine used for this experiment was inactivated virus vaccine with mineral oil-Arlacel adjuvant. The induction of antibody level by the inoculation of this vaccine was evidenced to be very efficient and the duration of the immunity was also very satisfactory. However, after the cessation of the vaccination, the infection of the virus reappeared gradually after some period of temporary ease.