Molecular epidemiology of an outbreak of human parainfluenza virus 3 among oncology patients.

A hospital outbreak of human parainfluenza virus type 3 (HPIV-3) in haematologic oncology patients is described in 12 patients over a four-week period. Exposure histories and molecular analysis of HPIV-3 isolates suggest that both community-acquired and nosocomially transmitted infections occurred during this outbreak. Molecular analysis of HPIV-3 isolates indicated that a chain of transmission occurred among multiple patients in an oncology ward. This transmission was later determined to be associated with the movement of fomites, visitors, and activities in the unit. The infection prevention team stopped nosocomial spread of HPIV-3 through interventions including advanced cleaning procedures.

The role of next generation sequencing in infection prevention in human parainfluenza virus 3 infections in immunocompromised patients.

BACKGROUND: Respiratory viral infections are a significant problem in patients with hematologic malignancies. We report a cluster of HPIV 3 infections in our myeloma patients, and describe the utility of next generation sequencing (NGS) to identify transmission linkages which can assist in infection prevention. OBJECTIVES: To evaluate the utility of NGS to track respiratory viral infection outbreaks and delineate between community acquired and nosocomial infections in our cancer units. STUDY DESIGN: Retrospective chart review conducted at a single site. All patients diagnosed with multiple myeloma who developed symptoms suggestive of upper respiratory tract infection (URTI) or lower respiratory tract infection (LRTI) along with a respiratory viral panel (RVP) test positive for HPIV 3 between April 1, 2016, to June 30, 2016, were included. Sequencing was performed on the Illumina MiSeq™. To gain understanding regarding community strains of HPIV 3 during the same season, we also performed NGS on HPIV3 strains isolated from pediatric cases. RESULTS: We saw a cluster of 13 cases of HPIV3 infections in the myeloma unit. Using standard epidemiologic criteria, 3 cases were considered community acquired, 7 cases developed infection during treatment in the cancer infusion center, while an additional 3 developed infections during hospital stay. Seven patients required hospitalization for a median duration of 20days. NGS enabled sensitive discrimination of the relatedness of the isolates obtained during the outbreak and provided evidence for source of transmission. Two hospital onset infections could be tracked to an index case; the genome sequences of HPIV 3 strains from these 3 patients only differed by a single nucleotide. CONCLUSIONS: NGS offers a significantly higher discriminatory value as an epidemiologic tool, and can be used to gather real-time information and identification of transmission linkages to assist in infection prevention in immunocompromised patients.

Nosocomial transmission of parainfluenza 3 virus in hematological patients characterized by molecular epidemiology.

We report an outbreak of parainfluenza 3 virus involving 17 hematology-oncology patients on 2 hospital wards. Sequence analysis of clinical samples confirmed homology of strains for 16/17 patients and 1 healthcare worker. Epidemiological analysis of the outbreak supported the molecular data with nosocomial transmission of the same genetic strain as the cause of the outbreak.

Development of immunostimulatory virotherapy using non-transmissible Sendai virus-activated dendritic cells.

Dendritic cell (DC)-based immunotherapy has been clinically evaluated, however, still requires modification to improve its outcomes. We previously demonstrated that DCs activated by replication competent recombinant Sendai virus (SeV) showed dramatic efficacy over that seen in use of current DC vaccine for immunotherapy against malignancies; however, application of replication-deficient vector is more relevant in clinical setting. We here show that F-gene-deleted non-transmissible Sendai virus (SeV/dF)-activated DCs (DCs/SeV/dF) has strong antitumor effects against murine SCCVII tumor, that was well-known as a less immunogenic cell line. SeV/dF shows high transfection efficiency to DCs and leads them to upregulate costimulatory molecules. Intratumoral injection of DCs/SeV/dF resulted in a marked and representative inhibition of the tumor, even when the tumors were well-vascularized. This is the first demonstration that non-transmissible SeV vector, SeV/dF, could be a DC-activator; DC/SeV/dF-based cancer immunotherapy may, therefore, warrant further investigation.

Prolonged outbreak of human parainfluenza virus 3 infection in a stem cell transplant outpatient department: insights from molecular epidemiologic analysis.

Human parainfluenza virus type 3 (hPIV3) infections cause considerable morbidity and mortality after stem cell transplantation, and inpatient nosocomial outbreaks are common. From September 1998 to July 1999, 93 stem cell transplantation recipients at our institution contracted hPIV3, of which 66 (71%) were being followed up in our outpatient department (OPD). The peak incidence was in September and October, when 39 cases were identified; thereafter, hPIV3 incidence decreased to approximately 5 cases per month. Nucleotide sequences (778 nucleotides from variable regions of the hemagglutinin-neuraminidase gene) from 46 patient and 8 community hPIV3 isolates were compared to determine epidemiologic relatedness. Sequence analysis of OPD isolates revealed that 18 of 19 isolates from September and October and 11 of 15 isolates from November 1998 to July 1999 were genetically similar. In contrast, 2 of 3 community isolates from September and October and 0 of 5 from November to July were linked to this cluster. Symptomatic surveillance and isolation were ineffective in terminating the outbreak, suggesting asymptomatic shedding among patients, staff, or visitors or viral persistence on environmental surfaces as possible explanations. The concept of nosocomial transmission should be expanded to include the OPD for immunosuppressed patients.

Exogenous porcine viruses.

Porcine organs, cells and tissues provide a viable source of transplants in humans, though there is some concern of public health risk from adaptation of swine infectious agents in humans. Limited information is available on the public health risk of many exogenous swine viruses, and reliable and rapid diagnostic tests are available for only a few of these. The ability of several porcine viruses to cause transplacental fetal infection (parvoviruses, circoviruses, and arteriviruses), emergence or recognition of several new porcine viruses during the last two decades (porcine circovirus, arterivirus, paramyxoviruses, herpesviruses, and porcine respiratory coronavirus) and the immunosuppressed state of the transplant recipients increases the xenozoonoses risk of humans to porcine viruses through transplantation. Much of this risk can be eliminated with vigilance and sustained monitoring along with a better understanding of pathogenesis and development of better diagnostic tests. In this review we present information on selected exogenous viruses, highlighting their characteristics, pathogenesis of viral infections in swine, methods for their detection, and the potential xenozoonoses risk they present. Emphasis has been given in this review to swine influenza virus, paramyxovirus (Nipah virus, Menagle virus, LaPiedad paramyxovirus, porcine paramyxovirus), arterivirus (porcine reproductive and respiratory syndrome virus) and circovirus as either they represent new swine viruses or present the greatest risk. We have also presented information on porcine parvovirus, Japanese encephalitis virus, encephalomyocarditis virus, herpesviruses (pseudorabies virus, porcine lymphotropic herpesvirus, porcine cytomegalovirus), coronaviruses (TGEV, PRCV, HEV, PEDV) and adenovirus. The potential of swine viruses to infect humans needs to be assessed in vitro and in vivo and rapid and more reliable diagnostic methods need to be developed to assure safe supply of porcine tissues and cells for xenotransplantation.

Primary replication of a recombinant Sendai virus vector in macaques.

An efficient antigen expression system using a recombinant Sendai virus (SeV) has been established recently and its potential to induce resistance against immunodeficiency virus infections in macaques has been shown. SeV replication has been well characterized in mice, the natural host, but not in primates, including humans. Here, primary SeV replication was investigated in macaques. After intranasal immunization with a recombinant SeV expressing simian immunodeficiency virus Gag protein, SeV-Gag, robust gag expression was observed in the nasal mucosa and much lower but significant levels of gag expression were observed in the local retropharyngeal and submandibular lymph nodes (LN). Expression peaked within a week and lasted at least up to 13 days after immunization. SeV-Gag was isolated from nasal swabs consistently at day 4 but not at all at day 13. Gag expression was undetectable in the lung as well as in remote lymphoid tissues, such as the thymus, spleen and inguinal LN, indicating that the spread of the virus was more restricted in macaques than in mice. SeV-specific T cells were detectable in SeV-immunized macaques at day 7. Finally, no naive macaques showed significant levels of anti-SeV antibodies in the plasma, even after living in a cage together with an acutely SeV-infected macaque for 5 weeks, indicating that SeV transmission from SeV-infected macaques to naive ones was inefficient. None of the SeV-immunized macaques displayed appreciable clinical manifestations. These results support the idea that this system may be used safely in primates, including humans.

Restricted replication of respiratory syncytial virus in human alveolar macrophages.

The cellular factors that regulate infection and replication of respiratory syncytial virus (RSV) in human alveolar macrophages were examined. RSV-exposed alveolar macrophages demonstrated a time-dependent expression of viral glycoproteins, maximal by 24 h post-infection resulting in infection of approx. 38% of the cells. Essentially all (33%) of these freshly isolated alveolar macrophages replicated RSV as shown by infectious centre assays. This RSV-permissive subpopulation of alveolar macrophages consisted primarily of major histocompatibility class II-expressing cells as determined by fluorescence-activated cell sorting. Re-infection of alveolar macrophages did not significantly alter the number of cells infected or capable of replicating RSV. However, in vitro differentiation of alveolar macrophages prior to infection resulted in a significant (P < 0.05), time-dependent decrease (approx. sevenfold) in the number of cells that replicated virus. The mechanism by which cellular differentiation restricted RSV replication is unknown. Production of defective interfering particles did not account for this decrease. Alveolar macrophages infected with RSV produce a variety of cytokines potentially contributing to this restricted viral replication. Pretreatment with several of these cytokines did not affect viral infection or replication. However, tumour necrosis factor (TNF alpha) significantly (P < 0.05) decreased viral replication but only by 30 to 60%. Thus RSV replication is reduced by in vitro differentiation of alveolar macrophages and, to a lesser degree, by pretreatment with TNF.

Severe respiratory syncytial virus pneumonia after autologous bone marrow transplantation: a report of three cases and review.

Three patients with acute leukemia who underwent autologous bone marrow transplantation (BMT) in complete remission, developed a severe respiratory syncytial virus (RSV) pneumonia, which was fatal in two. Identification of RSV was made on the products of bronchoalveolar lavage by direct immunofluorescence. As already described by others, the initial course of RSV infection varies, depending on whether it occurs sooner or later after BMT with a better prognosis in the latter situation. Treatment consists of aerosolized ribavirin. Infection by RSV is caused by manual contact with infected persons and contaminated surfaces. The severity of lung RSV infection in the course of BMT suggests the need for prophylactic measures in addition to standard isolation precautions.

Screening for respiratory syncytial virus and assignment to a cohort at admission to reduce nosocomial transmission.

To limit nosocomial spread of respiratory syncytial virus (RSV) infection, a longitudinal intervention trial was instituted. Nasal secretions or washes were screened for RSV antigen by enzyme-linked immunosorbent assay, and patients were assigned to an RSV-infected or an RSV-uninfected cohort. The baseline (preintervention) rate of 7.17 nosocomial cases of RSV per 1000 patient-days of care was used for comparison. Despite continued infections in the community after screening was initiated, there were no cases of RSV infection in 1880 patient-days of care for 3 months (p = 0.039). During the fourth month, an RSV-infected child was erroneously assigned to the RSV-uninfected cohort, and three nosocomial cases occurred--5.33/1000 patient-days of care (p = 0.286). Overall, there were three nosocomial RSV infections in 2443 patient-days of care in the 1987 season after screening was introduced--1.23/1000 patient-days of care (p = 0.026). In the subsequent RSV season, there was one nosocomial case--0.461/1000 patient-days of care for 3 months (p = 0.0074). During the same period, nosocomial cases of RSV were observed in the pediatric and neonatal intensive care units, where assignment to a cohort was not possible. We conclude that entry into a cohort at the time of admission, on the basis of prospective RSV screening by enzyme-linked immunosorbent assay, effectively reduces nosocomial transmission of RSV.

Day-care center attendance and hospitalization for lower respiratory tract illness.

To identify risk factors associated with hospitalization for acute lower respiratory tract illness, 102 children less than 2 years of age admitted to four Atlanta metropolitan area hospitals between December 1984 and June 1985 with the diagnosis of lower respiratory tract illness were studied. The most common causative agent associated with illness was respiratory syncytial virus, followed by other respiratory viruses, Haemophilus influenzae, and Streptococcus pneumoniae. The 102 case-patients were compared with 199 age- and sex-matched controls. A parent or guardian for each patient and control was interviewed by telephone regarding demographic data, care outside the home, breast-feeding, previous medical history, allergies, and smoking and illness in household members. Five factors were associated with lower respiratory tract illness in both a univariate analysis and a multiple logistic regression model (P less than .05). These factors were the number of people sleeping in the same room with the child, a lack of immunization the month before the patient was hospitalized, prematurity, a history of allergy, and regular attendance in a day-care center (more than six children in attendance). Care received outside of the home in a day-care home (less than or equal to six children in attendance) was not associated with lower respiratory tract illness. The suggestion made by our study and other studies was that for children less than 2 years of age, care outside of the home is an important risk factor for acquiring lower respiratory tract illness, as well as other infectious diseases, and that this risk can be reduced by using a day-care home instead of a day-care center.

Respiratory disease and wasting in athymic mice infected with pneumonia virus of mice.

Although pneumonia virus of mice (PVM) is ubiquitous among rodent colonies in the United States, it has not been reported to cause clinically apparent disease in euthymic mice. However, PVM has been reported to cause respiratory disease and death in experimentally infected euthymic and athymic mice. A group of nu/nu mice, housed in quarantine in a Trexler-type isolator, had weight loss and dyspnea. Gross necropsy findings included cachexia and diffuse pulmonary edema or lobar consolidation. Histologically there was diffuse interstitial pneumonia. Electron microscopy revealed filamentous virions budding from plasma membranes, and immunohistochemical staining of lung tissue was positive for PVM antigen. PVM was isolated from affected lung tissue in BHK 21 cells and mouse antibody production tests resulted in seroconversion to PVM. Experimental inoculation of athymic mice with lung homogenate from spontaneously infected mice resulted in clinically apparent respiratory disease and histologic lung changes similar to those in naturally infected mice. Inoculation of athymic mice with infected BHK 21 cell culture fluid resulted in pneumonia which was qualitatively similar to, but less severe than, that observed in mice with spontaneous disease. These findings indicate that naturally occurring PVM infection in athymic mice may cause respiratory disease and wasting.