Evaluation of a new dengue 3 controlled human infection model for use in the evaluation of candidate dengue vaccines.

All four serotypes of dengue virus (DENV) cause the full spectrum of disease. Therefore, vaccines must protect against all serotypes. To evaluate candidate vaccines, a human challenge model of dengue serotype 3 (rDEN30Δ30) was developed. All challenge virus recipients safely met the primary endpoint of viremia and secondary endpoints of rash and seroconversion to DENV-3.

Mental health and COVID-19: The impact of a virtual course for family caregivers of adults with intellectual and developmental disabilities.

BACKGROUND: The COVID-19 pandemic has significantly impacted family caregivers of adults with intellectual and developmental disabilities (IDD). This study evaluated a virtual course for family caregivers from across Canada, focused on supporting the mental health and well-being of adults with IDD and their families. The evaluation examined the feasibility and acceptability of the course, as well as the impact of the intervention on participants' overall health and well-being. METHODS: The 6-week virtual course, informed by a parallel Extension for Community Healthcare Outcomes (ECHO) course for service providers, combined didactic instruction with applied activities. A total of 126 family caregiver course participants consented to be part of the research evaluation delivered over three cycles between October 2020 and April 2021. Attendance was measured at each weekly session. Satisfaction was assessed weekly and post-program. Learning, self-efficacy, and well-being were assessed pre- and post-course, and again at follow-up (8 weeks post-course). Mixed-effects models assessed changes between and within individuals across time. RESULTS: Participants had consistent attendance, low-dropout rates, and reported high satisfaction, with 93% of participants reporting that their expectations for the course were met. Compared with pre-course, participants reported improved self-efficacy and well-being post-course, which were maintained at follow-up. CONCLUSIONS: An interactive and applied virtual education course delivered to a large group of family caregivers of adults with IDD was both feasible and acceptable. It positively impacted participants' well-being by offering much needed mental health support and creating a peer-led community of practice.

Changes in community and hospital-based health care use during the COVID-19 pandemic for adults with and without intellectual and developmental disabilities.

BACKGROUND: Due to the functional, cognitive and communication impairments associated with intellectual and/or developmental disabilities (IDD), adaptations to service delivery during the COVID-19 pandemic may impact people with IDD differently than others. For community and hospital-based services, this study describes the proportion of adults with and without IDD who used health care in the year pre-COVID-19 and the first year of the pandemic. METHODS: This retrospective cohort study used linked health administrative databases to identify adults aged 18-105 years with and without IDD using unique encoded identifiers. Counts and proportions of adults who used health care services were reported for the pre-COVID-19 year (16 March 2019 to 14 March 2020) and the first COVID-19 year (15 March 2020 to 15 March 2021). RESULTS: Across services, the proportion of adults who used services was lower during the first COVID-19 year compared with the year prior, except for virtual physician visits that increased markedly for people with and without IDD. While the proportion of adults who used services was higher for those with IDD compared with those without IDD for both years, differences were greatest for mental health emergency visits and hospitalisations; adults with IDD were 6.3 to 10.9 times more likely to use these services than others with no IDD during the pandemic. CONCLUSIONS: During the first COVID-19 year in Ontario, Canada, service use decreased for all service types, except for virtual physician visits. In both years, adults with IDD remained more likely to use services than other adults, with the largest differences in use of mental health hospitalisations and mental health emergency department visits.

Pre-vaccination screening strategies for the use of the CYD-TDV dengue vaccine: A meeting report.

The first licensed dengue vaccine, CYD-TDV (Dengvaxia) is efficacious in seropositive individuals, but increases the risk for severe dengue in seronegative persons about two years after administration of the first dose. For countries considering the introduction of Dengvaxia, WHO recommends a pre-vaccination screening strategy whereby only persons with evidence of a past dengue infection would be vaccinated. Policy-makers need to consider the risk-benefit of vaccination strategies based on such screening tests, the optimal age to introduce the vaccine, communication and implementation strategies. To address these questions, the Global Dengue and Aedes-transmitted diseases Consortium (GDAC) organized a 3-day workshop in January 2019 with country representatives from Asia and Latin America. The meeting discussions highlighted many challenges in introducing Dengvaxia, in terms of screening test characteristics, costs of such tests combined with a 3-dose schedule, logistics, achieving high coverage rates, vaccine confidence and communication; more challenges than for any other vaccine introduction programme. A screening test would require a high specificity to minimize individual risk, and at the same time high sensitivity to maximize individual and population benefit. The underlying seroprevalence dependent positive predictive value is the best indicator for an acceptable safety profile of a pre-vaccination screening strategy. The working groups discussed many possible implementation strategies. Addressing the bottlenecks in school-based vaccine introduction for Dengvaxia will also benefit other vaccines such as HPV and booster doses for tetanus and pertussis. Levels of public trust are highly variable and context specific, and understanding of population perceptions and concerns is essential to tailor interventions, monitor and mitigate risks.

Meeting Report: WHO consultation on considerations for regulatory expectations of Zika virus vaccines for use during an emergency.

On 1 February 2016, in the context of the ongoing Zika virus epidemic, the WHO declared that the recently reported clusters of microcephaly and other neurological disorders constituted a Public Health Emergency of International Concern (PHEIC). In response, WHO in collaboration with UNICEF and a working group of independent subject matter experts developed a Zika virus vaccine Target Product Profile (TPP) for use in an emergency, or in a future outbreak scenario. The drafting process of the Zika virus vaccine TPP included the opportunity for public comment, as well as consultation with epidemiologists, flavivirus vaccine subject matter experts, vaccine developers and global regulators to consider the regulatory expectations and potential emergency use pathways for a vaccine with the characteristics described in the TPP. This report summarizes an expert consultation held 6-7 June 2016 on the regulatory considerations for a Zika vaccine for emergency use.

How HIV affects health and service use for adults with intellectual and developmental disabilities.

OBJECTIVE(S): Although rates of human immunodeficiency virus (HIV) are similar for individuals with and without intellectual and developmental disabilities (IDD), very little is known about the health needs and service use of those with IDD and HIV. Among a population with IDD, we compared the physical and mental health profiles, as well as general and mental health service use for those with and without HIV. DESIGN: Retrospective cohort study in Ontario, Canada using linked administrative health and social service databases. METHODS: The prevalence of physical conditions and mental health disorders, and patterns of service use for any reason and service use for mental health issues were compared among Ontario adults with IDD and HIV (n = 107) and without HIV (n = 63 901) in log-binomial models adjusted for age, sex and neighbourhood income and rurality. RESULTS: Adults with IDD and HIV were more likely than those without HIV to have three types of mental health disorders: non-psychotic disorders [aRR: adjusted rate ratio (aRR): 1.22 (95% confidence interval (CI): 1.01-1.47)], psychotic disorders [aRR: 1.57 (1.09, 2.28)] and substance use disorders [aRR: 3.52 (2.53, 4.91)]. Adults with IDD and HIV were also more likely to have emergency department visits [aRR: 1.68 (1.42, 1.98)] and hospital admissions [aRR: 2.55 (1.74, 3.73)] for any reason, and to have mental health emergency department visits and/or admissions [aRR: 2.82 (1.90, 4.18)]. DISCUSSION: Adults with IDD and HIV have complex health profiles and greater health service use than HIV-negative adults with IDD. These findings call for closer integration of programs delivered by the HIV and disability sectors to optimise the health of this patient population.

Needs among persons with human immunodeficiency virus and intellectual and developmental disabilities in community mental health care: a cross-sectional study.

BACKGROUND: The experience of having human immunodeficiency virus (HIV) is often associated with co-occurring mental health issues. Community mental health services are an important source of support for persons with HIV living in the community. Persons with intellectual disability (ID) are vulnerable to HIV and may have unique support needs beyond those without ID receiving community care. This study compared support needs of men with HIV in community mental health programmes, with and without ID. METHODS: The sample was composed of 138 HIV-positive men with and without ID receiving mental health case management from one community organisation in Ontario, Canada, on 31 March 2013. Staff-rated needs across 16 domains grouped into four clusters were measured using the Camberwell Assessment of Need: Basic needs (accommodation, food, public transportation, money and benefits); self-care/functional needs (looking after the home, self-care and daytime activities); health/safety needs (physical health, psychological distress, psychotic symptoms, safety to self and safety to others); and social needs (company, intimate relationships and sexual expression). Adjusted logistic regression models examined the association between ID and each need domain. RESULTS: One-quarter of the sample (n = 34/138, 24.6%) had co-occurring ID. Those with ID were more likely to have needs in the basic cluster [odds ratios: food 4.05 (1.14, 14.44), P:0.031; benefits 2.58 (1.05, 6.32), P:0.038)] and self-care/functional cluster [looking after the home (2.75 (1.17, 6.49), P:0.021); self-care (2.72 (1.18, 6.27), P:0.019)], but were less likely to have need for sexual expression: 0.35 (0.14,0.90), P:0.030) (social cluster). There were no differences in the domains in the health/safety cluster. CONCLUSION: Despite elevated cognitive needs in the basic and self-care/functional clusters for the ID group, limited other differences suggest that with moderate additional targeting, community mental health programmes for persons with HIV may be appropriate for men with ID.

A new quaternary structure epitope on dengue virus serotype 2 is the target of durable type-specific neutralizing antibodies.

UNLABELLED: Dengue virus serotype 2 (DENV2) is widespread and responsible for severe epidemics. While primary DENV2 infections stimulate serotype-specific protective responses, a leading vaccine failed to induce a similar protective response. Using human monoclonal antibodies (hMAbs) isolated from dengue cases and structure-guided design of a chimeric DENV, here we describe the major site on the DENV2 envelope (E) protein targeted by neutralizing antibodies. DENV2-specific neutralizing hMAb 2D22 binds to a quaternary structure epitope. We engineered and recovered a recombinant DENV4 that displayed the 2D22 epitope. DENV2 neutralizing antibodies in people exposed to infection or a live vaccine tracked with the 2D22 epitope on the DENV4/2 chimera. The chimera remained sensitive to DENV4 antibodies, indicating that the major neutralizing epitopes on DENV2 and -4 are at different sites. The ability to transplant a complex epitope between DENV serotypes demonstrates a hitherto underappreciated structural flexibility in flaviviruses, which could be harnessed to develop new vaccines and diagnostics. IMPORTANCE: Dengue virus causes fever and dengue hemorrhagic fever. Dengue serotype 2 (DENV2) is widespread and frequently responsible for severe epidemics. Natural DENV2 infections stimulate serotype-specific neutralizing antibodies, but a leading DENV vaccine did not induce a similar protective response. While groups have identified epitopes of single monoclonal antibodies (MAbs), the molecular basis of DENV2 neutralization by polyclonal human immune sera is unknown. Using a recombinant DENV displaying serotype 2 epitopes, here we map the main target of DENV2 polyclonal neutralizing antibodies induced by natural infection and a live DENV2 vaccine candidate. Proper display of the epitope required the assembly of viral envelope proteins into higher-order structures present on intact virions. Despite the complexity of the epitope, it was possible to transplant the epitope between DENV serotypes. Our findings have immediate implications for evaluating dengue vaccines in the pipeline as well as designing next-generation vaccines.

Verrucomicrobia are candidates for polysaccharide-degrading bacterioplankton in an arctic fjord of Svalbard.

In Arctic marine bacterial communities, members of the phylum Verrucomicrobia are consistently detected, although not typically abundant, in 16S rRNA gene clone libraries and pyrotag surveys of the marine water column and in sediments. In an Arctic fjord (Smeerenburgfjord) of Svalbard, members of the Verrucomicrobia, together with Flavobacteria and smaller proportions of Alpha- and Gammaproteobacteria, constituted the most frequently detected bacterioplankton community members in 16S rRNA gene-based clone library analyses of the water column. Parallel measurements in the water column of the activities of six endo-acting polysaccharide hydrolases showed that chondroitin sulfate, laminarin, and xylan hydrolysis accounted for most of the activity. Several Verrucomicrobia water column phylotypes were affiliated with previously sequenced, glycoside hydrolase-rich genomes of individual Verrucomicrobia cells that bound fluorescently labeled laminarin and xylan and therefore constituted candidates for laminarin and xylan hydrolysis. In sediments, the bacterial community was dominated by different lineages of Verrucomicrobia, Bacteroidetes, and Proteobacteria but also included members of multiple phylum-level lineages not observed in the water column. This community hydrolyzed laminarin, xylan, chondroitin sulfate, and three additional polysaccharide substrates at high rates. Comparisons with data from the same fjord in the previous summer showed that the bacterial community in Smeerenburgfjord changed in composition, most conspicuously in the changing detection frequency of Verrucomicrobia in the water column. Nonetheless, in both years the community hydrolyzed the same polysaccharide substrates.

Microbial community composition and function in permanently cold seawater and sediments from an arctic fjord of svalbard.

Heterotrophic microbial communities in seawater and sediments metabolize much of the organic carbon produced in the ocean. Although carbon cycling and preservation depend critically on the capabilities of these microbial communities, their compositions and capabilities have seldom been examined simultaneously at the same site. To compare the abilities of seawater and sedimentary microbial communities to initiate organic matter degradation, we measured the extracellular enzymatic hydrolysis rates of 10 substrates (polysaccharides and algal extracts) in surface seawater and bottom water as well as in surface and anoxic sediments of an Arctic fjord. Patterns of enzyme activities differed between seawater and sediments, not just quantitatively, in accordance with higher cell numbers in sediments, but also in their more diversified enzyme spectrum. Sedimentary microbial communities hydrolyzed all of the fluorescently labeled polysaccharide and algal extracts, in most cases at higher rates in subsurface than surface sediments. In seawater, in contrast, only 5 of the 7 polysaccharides and 2 of the 3 algal extracts were hydrolyzed, and hydrolysis rates in surface and deepwater were virtually identical. To compare bacterial communities, 16S rRNA gene clone libraries were constructed from the same seawater and sediment samples; they diverged strongly in composition. Thus, the broader enzymatic capabilities of the sedimentary microbial communities may result from the compositional differences between seawater and sedimentary microbial communities, rather than from gene expression differences among compositionally similar communities. The greater number of phylum- and subphylum-level lineages and operational taxonomic units in sediments than in seawater samples may reflect the necessity of a wider range of enzymatic capabilities and strategies to access organic matter that has already been degraded during passage through the water column. When transformations of marine organic matter are considered, differences in community composition and their different abilities to access organic matter should be taken into account.

Attenuation and immunogenicity in humans of a live dengue virus type-4 vaccine candidate with a 30 nucleotide deletion in its 3'-untranslated region.

The recombinant dengue virus type-4 vaccine candidate 2AA30 was attenuated in rhesus monkeys due to an engineered 30-nucleotide deletion in the 3'-untranslated region of the viral genome. A clinical trial to evaluate the safety and immunogenicity of a single dose of 2Adelta30 was conducted with 20 adult human volunteers. The vaccine candidate was well tolerated and did not cause systemic illness in any of the 20 volunteers. Viremia was detectable in 14 volunteers at a mean level of 1.6 log10 plaque-forming units/ml of serum, although all 20 volunteers seroconverted with a seven-fold or greater increase in serum neutralizing antibody titer on day 28 post-vaccination (mean titer = 1:580). A mild, asymptomatic, macular rash developed in 10 volunteers, and a transient elevation in the serum level of alanine aminotransferase was noted in five volunteers. The low level of reactogenicity and high degree of immunogenicity of this vaccine candidate warrant its further evaluation and its use to create chimeric vaccine viruses expressing the structural genes of dengue virus types 1, 2, and 3.

A live attenuated recombinant dengue-4 virus vaccine candidate with restricted capacity for dissemination in mosquitoes and lack of transmission from vaccinees to mosquitoes.

2Adelta30 is a live dengue-4 virus vaccine candidate with a 30-nucleotide deletion in its 3'-untranslated region. To assess the transmissibility of 2Adelta30 by mosquitoes, we compared its in vivo replication in mosquitoes with that of its wild type DEN-4 parent. Both the vaccine candidate and wild type virus were equally able to infect the mosquito Toxorhynchites splendens after intrathoracic inoculation. Relative to its wild type parent, 2Adelta30 was slightly restricted in its ability to infect the midgut of Aedes aegypti mosquitoes fed on an artificial blood meal and was even more restricted in its ability to disseminate from the midgut to the salivary glands. Thus, the 30-nucleotide deletion rendered the vaccine candidate more sensitive than its wild type parent to the mosquito midgut escape barrier. Most significantly, 2Adelta30 was not transmitted to 352 Ae. albopictus mosquitoes fed on 10 vaccinees, all of whom were infected with the vaccine candidate.

Human parainfluenza virus type 3 (PIV3) expressing the hemagglutinin protein of measles virus provides a potential method for immunization against measles virus and PIV3 in early infancy.

Recombinant human parainfluenza virus type 3 (PIV3) was used as a vector to express the major protective antigen of measles virus, the hemagglutinin (HA) glycoprotein, in order to create a bivalent PIV3-measles virus that can be administered intranasally. The measles virus HA open reading frame (ORF) was inserted as an additional transcriptional unit into the N-P, P-M, or HA-neuraminidase (HN)-L gene junction of wild-type PIV3 or into the N-P or P-M gene junction of an attenuated derivative of PIV3, termed rcp45L. The recombinant PIV3 (rPIV3) viruses bearing the HA inserts replicated more slowly in vitro than their parental viruses but reached comparable peak titers of >/=10(7.5) 50% tissue culture infective doses per ml. Each of the wild-type or cold-passaged 45L (cp45L) PIV3(HA) chimeric viruses replicated 5- to 10-fold less well than its respective parent virus in the upper respiratory tract of hamsters. Thus, insertion of the approximately 2-kb ORF itself conferred attenuation, and this attenuation was additive to that conferred by the cp45L mutations. The attenuated cp45L PIV3(HA) recombinants induced a high level of resistance to replication of PIV3 challenge virus in hamsters and induced very high levels of measles virus neutralizing antibodies (>1:8,000) that are well in excess of those known to be protective in humans. rPIV3s expressing the HA gene in the N-P or P-M junction induced about 400-fold more measles virus-neutralizing antibody than did the rPIV3 with the HA gene in the HN-L junction, indicating that the N-P or P-M junction appears to be the preferred insertion site. Previous studies indicated that the PIV3 cp45 virus, a more attenuated version of rcp45L, replicates efficiently in the respiratory tract of monkeys and is immunogenic and protective even when administered in the presence of very high titers of passively transferred PIV3 antibodies (A. P. Durbin, C. J. Cho, W. R. Elkins, L. S. Wyatt, B. Moss, and B. R. Murphy, J. Infect. Dis. 179:1345-1351, 1999). This suggests that this intranasally administered PIV3(HA) chimeric virus can be used to immunize infants with maternally acquired measles virus antibodies in whom the current parenterally administered live measles virus vaccine is ineffective.

Long nucleotide insertions between the HN and L protein coding regions of human parainfluenza virus type 3 yield viruses with temperature-sensitive and attenuation phenotypes.

Recombinant parainfluenza virus 3 (rPIV3) is being developed as a vector to express foreign genes as a bivalent or multivalent live attenuated virus vaccine. In the present study, we examined the effect of inserted foreign sequence on virus replication in vitro and in vivo, focusing on the parameter of insert length. In one type of construct, foreign sequence of increasing length was flanked by PIV3 transcription signals and inserted as an additional gene unit (GU insert) between the HN and L genes, so that one additional mRNA would be made. In a second type of construct, foreign sequence was inserted into the downstream NCR (NCR insert) of the HN gene, so that the number of encoded mRNAs remained unchanged. In each case, the foreign sequence was designed to lack any significant open reading frame, which permitted an evaluation of the effect of insert length on replication independent of an effect of an expressed protein. The GU or NCR insert sizes ranged from 168 nucleotides (nt) to 3918 nt. rPIV3s containing GU insertions of up to 3918 nt in length, the largest size tested, were viable and replicated efficiently at permissive temperatures in vitro, but a reduction in plaque size was seen at 39 degrees C and 40 degrees C. The rPIV3 with a 3918-nt GU insertion was restricted in replication in the upper (fivefold) and lower (25-fold) respiratory tracts of hamsters. Although a 1908-nt GU insertion did not significantly modify replication of wild-type PIV3 in vitro or in vivo, its introduction significantly augmented the level of temperature sensitivity (ts) and attenuation (att) specified by three mutations in the L protein of a cold-passaged attenuated PIV3 vaccine virus. rPIV3s bearing a 3126- or 3894-nt NCR insertion exhibited in vitro and in vivo phenotypes like those of the rPIV3s bearing similar-sized GU insertions. These findings indicate that rPIV3s whose genome length has been increased by more than 3000 nt by either a GU or an NCR insertion exhibit an unexpected host-range phenotype, that is, efficient replication in vitro but restricted replication in hamsters, especially in the lower respiratory tract. Furthermore, these effects were greatly enhanced when the rPIV3 backbone contained other ts or att mutations. The implications of these findings for the use of single-stranded, negative-sense RNA viruses as vectors for vaccines are discussed.

African green monkeys provide a useful nonhuman primate model for the study of human parainfluenza virus types-1, -2, and -3 infection.

Human parainfluenza virus (HPIV) types-1, -2, and -3 are significant causes of both upper and lower respiratory tract disease in infants and children. Although there are two live attenuated vaccines for the prevention of HPIV-3 disease in phase 1 clinical trials, vaccines are not currently available for prevention of HPIV-1 or -2 disease. Our laboratory is developing candidate vaccines for the prevention of HPIV-1, -2, and -3 disease, and a suitable nonhuman primate model is needed for evaluation of these vaccine candidates prior to administration to humans. We evaluated the replication of HPIV-1 and -2 in six different species of nonhuman primates and found both viruses to replicate most efficiently in African green monkeys and chimpanzees. We then compared the replication of HPIV-3 in African green monkeys to that in rhesus macaques, which we have used previously, and found that HPIV-3 replicated to higher titer in African green monkeys. In summary, African green monkeys provide a very useful nonhuman primate for the evaluation of HPIV-1, -2, and -3 vaccine candidates, especially for the evaluation of various combinations of these PIV vaccines and for vaccine strategies that employ sequential immunization.

A recombinant human parainfluenza virus type 3 (PIV3) in which the nucleocapsid N protein has been replaced by that of bovine PIV3 is attenuated in primates.

The shipping fever (SF) and Kansas (Ka) strains of bovine parainfluenza virus type 3 (BPIV3) are restricted in their replication in rhesus monkeys 100- to 1,000-fold compared to human parainfluenza virus type 3 (HPIV3), and the Ka strain also was shown to be attenuated in humans. To initiate an investigation of the genetic basis of the attenuation of BPIV3 in primates, we produced viable chimeric HPIV3 recombinants containing the nucleoprotein (N) open reading frame (ORF) from either BPIV3 Ka or SF in place of the HPIV3 N ORF. These chimeric recombinants were designated cKa-N and cSF-N, respectively. Remarkably, cKa-N and cSF-N grew to titers comparable to those of their HPIV3 and BPIV3 parents in LLC-MK2 monkey kidney and Madin-Darby bovine kidney cells. Thus, the heterologous nature of the N protein did not impede replication in vitro. However, cKa-N and cSF-N were each restricted in replication in rhesus monkeys to a similar extent as Ka and SF, respectively. This identified the BPIV3 N protein as a determinant of the host range restriction of BPIV3 in primates. These chimeras thus combine the antigenic determinants of HPIV3 with the host range restriction and attenuation phenotype of BPIV3. Despite their restricted replication in rhesus monkeys, the chimeric viruses induced a level of resistance to HPIV3 challenge in these animals which was indistinguishable from that conferred by immunization with HPIV3. The infectivity, attenuation, and immunogenicity of these BPIV3/HPIV3 chimeras suggest that the modified Jennerian approach described in the present report represents a novel method to design vaccines to protect against HPIV3-induced disease in humans.

A live attenuated recombinant chimeric parainfluenza virus (PIV) candidate vaccine containing the hemagglutinin-neuraminidase and fusion glycoproteins of PIV1 and the remaining proteins from PIV3 induces resistance to PIV1 even in animals immune to PIV3.

Using a reverse genetics system for PIV3, we previously recovered recombinant chimeric PIV3-PIV1 virus bearing the major protective antigens of PIV1, the hemaglutinin-neuraminidase and fusion proteins, on a background of PIV3 genes bearing temperature sensitive (ts) and attenuating mutations in the L gene. Immunization of hamsters with this virus, designated rPIV3-1.cp45L, induced a high level of resistance to replication of wild type (wt) PIV1 and, surprisingly, also induced a moderate amount of restriction of the replication of PIV3 challenge virus. This suggested that some immunity is conferred by the internal PIV3 proteins shared by the two viruses. In the present study, we found that the immunity to PIV3 conferred by infection with rPIV3-1.cp45L is short-lived and completely disappeared four months after immunization, whereas resistance to replication of PIV3 induced by prior infection with PIV3 remains high even after an interval of four months. Since a live attenuated PIV1 vaccine such as the chimeric rPIV3-1.cp45L virus will likely be given to infants after a live attenuated PIV3 vaccine in a sequential immunization schedule, we examined the immunogenicity and efficacy of rPIV3-1.cp45L against PIV1 challenge in animals with and without prior immunity to PIV3. rPIV3-1.cp45L efficiently infected hamsters previously infected with wt or attenuated PIV3, but there was approximately a five-fold reduction in replication of rPIV3-1. cp45L virus in the PIV3-immune animals. This reduction in replication of rPIV3-1.cp45L in PIV3-immune animals was accompanied by a significant decrease in efficacy against PIV1 challenge. However, rPIV3-1.cp45L immunization of PIV3-immune animals induced a vigorous serum antibody response to PIV1 and reduced replication of PIV1 challenge virus 1000-fold in the lower respiratory tract and 25 to 200-fold in the upper respiratory tract. This study demonstrated that the recombinant chimeric rPIV3-1.cp45L candidate vaccine can induce immunity to PIV1 even in animals immune to PIV3. This establishes the feasibility of employing a sequential immunization schedule in which a recombinant chimeric rPIV3-1.cp45L vaccine is given following a live attenuated PIV3 vaccine.

Mutations in the C, D, and V open reading frames of human parainfluenza virus type 3 attenuate replication in rodents and primates.

Human parainfluenza virus type 3 (HPIV3) is a single-stranded negative-sense RNA virus belonging to the Respirovirus genus of the Paramyxoviridae family in the order Mononegavirales. The P gene encodes at least four proteins, including the C protein, which is expressed from an open reading frame (ORF) that overlaps the P ORF, and the D protein, which is encoded when the P ORF is fused to the D ORF by transcriptional editing. The P mRNA also contains a third ORF for the V protein, although it is unclear how or whether this ORF is accessed. We have used recombinant DNA technology to recover five mutant viruses that either interrupt or alter the C, D, and V ORFs. In one mutant virus, rC-KO, expression of the C protein was abrogated by changing the start codon from methionine to threonine and introducing two stop codons at amino acid positions 7 and 26 of the C ORF. In a second mutant virus, rF164S, a point mutation was introduced into the C ORF changing amino acid position 164 from phenylalanine (F) to serine (S), which corresponds to the F170S mutation described in the C protein of Sendai virus (Itoh et al., J. Gen. Virol. 78, 3207-3215). rC-KO was significantly attenuated in vitro and in vivo (rodents and primates), whereas rF164S was attenuated only in vivo. Interestingly, the rF164S mutant was more attenuated in the upper than in the lower respiratory tract of hamsters and monkeys. This pattern is the converse of that seen with temperature-sensitive attenuating mutations, and thus inclusion of this novel mutation in a recombinant live-attenuated vaccine candidate might prove useful in reducing residual virulence in the upper respiratory tract. Both rC-KO and rF164S conferred protection against challenge with wild-type HPIV3. In three other viruses, the D and V ORFs were interrupted singly or in combination. Although interruption of the D and V ORFs individually did not affect virus replication in vitro or in vivo, interruption of both together attenuated replication in vivo. These results indicate that the C, D, and V proteins of HPIV3 each has a role in virus replication in vitro, in vivo, or both, and define mutations that might be useful for the development of a vaccine against HPIV3.

Comparison of the immunogenicity and efficacy of a replication-defective vaccinia virus expressing antigens of human parainfluenza virus type 3 (HPIV3) with those of a live attenuated HPIV3 vaccine candidate in rhesus monkeys passively immunized with PIV3 antibodies.

Two parainfluenza virus type 3 (PIV3) vaccine candidates-cp45, a live attenuated derivative of the JS wild type (wt), and a replication-defective vaccinia virus recombinant expressing the hemagglutinin-neuraminidase or fusion glycoprotein of human PIV3 (modified vaccinia virus Ankara [MVA]/PIV3 recombinants)-were evaluated in rhesus monkeys to determine whether successful immunization could be achieved in the presence of passively transferred PIV3 antibodies. The cp45 virus, administered intranasally (in) and intratracheally (it) in the presence of high levels of PIV3 antibodies, replicated efficiently in the nasopharynx and protected against challenge with wt human PIV3. The MVA recombinants, administered in, it, and intramuscularly in the absence of passive antibody, conferred protection against replication of PIV3 wt challenge virus, but this was largely abrogated when immunization occurred in the presence of passive antibodies. Because immunization for the prevention of HPIV3 disease must occur in early infancy when maternal antibodies are present, the live attenuated cp45 virus continues to be a promising vaccine candidate for this age group.

A live attenuated chimeric recombinant parainfluenza virus (PIV) encoding the internal proteins of PIV type 3 and the surface glycoproteins of PIV type 1 induces complete resistance to PIV1 challenge and partial resistance to PIV3 challenge.

The recovery of wild type and attenuated human parainfluenza type 3 (PIV3) recombinant viruses has made possible a new strategy to rapidly generate a live-attenuated vaccine virus fof PIV1. We previously replaced the coding sequences for the hemagglutinin-neuraminidase (HN) and fusion (F) proteins of PIV3 with those of PIV1 in the PIV3 antigenomic cDNA. This was used to recover a fully-viable, recombinant chimeric PIV3-PIV1 virus, termed rPIV3-1, which bears the major protective antigens of PIV1 and is wild type-like with regard to growth in cell culture and in hamsters [Tao T, Durbin AP, Whitehead SS, Davoodi F, Collins PL, Murphy BR. Recovery of a fully viable chimeric human parainfluenza virus (PIV) type 3 in which the hemagglutinin-neuraminidase and fusion glycoprotein have been replaced by those of PIV type 1. J Virol 1998;72:2955-2961]. Here we report the recovery of a derivative of rPIV3-1 carrying the three temperature-sensitive and attenuating amino acid coding changes found in the L gene of the live-attenuated cp45 PIV3 candidate vaccine virus. This virus, termed rPIV3-1.cp45L, is temperature-sensitive with a shut-off temperature of 38 degrees C, which is similar to that of the recombinant rPIV3cp45L, which possesses the same three mutations. rPIV3-1.cp45L is attenuated in the respiratory tract of hamsters to the same extent as rPIV3cp45L. Infection of hamsters with rPIV3-1.cp45L generated a moderate level of hemagglutination-inhibiting antibodies against wild type PIV1 and induced complete resistance to challenge with wild type PIV1. This demonstrates that this novel attenuated chimeric virus is capable of inducing a highly effective immune response against PIV1. It confirms previous observations that the surface glycoproteins of parainfluenza viruses are sufficient to induce a high level of resistance to homologous virus challenge. Unexpectedly, infection with recombinant chimeric virus rPIV3-1.cp45L or rPIV3-1, each bearing the surface glycoprotein genes of PIV1 and the internal genes of PIV3, also induced a moderate level of resistance to replication of wild type PIV3 challenge virus. This indicates that the internal genes of PIV3 can independently induce protective immunity against PIV3 in rodents, albeit a lower level of resistance than that induced by the surface glycoproteins. Thus, a reverse genetics system for PIV3 has been used successfully to produce a live attenuated PIV1 vaccine candidate that is attenuated and protective in experimental infection in hamsters.