Experimental Hendra virus infection of dogs: virus replication, shedding and potential for transmission

OBJECTIVE

Characterisation of experimental Hendra virus (HeV) infection in dogs and assessment of associated transmission risk.

METHODS

Beagle dogs were exposed oronasally to Hendra virus/Australia/Horse/2008/Redlands or to blood collected from HeV-infected ferrets. Ferrets were exposed to oral fluids collected from dogs after canine exposure to HeV. Observations made and samples tested post-exposure were used to assess the clinical course and replication sites of HeV in dogs, the infectivity for ferrets of canine oral fluids and features of HeV infection in dogs following contact with infective blood.

RESULTS

Dogs were reliably infected with HeV and were generally asymptomatic. HeV was re-isolated from the oral cavity and virus clearance was associated with development of virus neutralising antibody. Major sites of HeV replication in dogs were the tonsils, lower respiratory tract and associated lymph nodes. Virus replication was documented in canine kidney and spleen, confirming a viraemic phase for canine HeV infection and suggesting that urine may be a source of infectious virus. Infection was transmitted to ferrets via canine oral secretions, with copy numbers for the HeV N gene in canine oral swabs comparable to those reported for nasal swabs of experimentally infected horses.

CONCLUSION

HeV is not highly pathogenic for dogs, but their oral secretions pose a potential transmission risk to people. The time-window for transmission risk is circumscribed and corresponds to the period of acute infection before establishment of an adaptive immune response. The likelihood of central nervous system involvement in canine HeV infection is unclear, as is any long-term consequence.

Henipavirus microsphere immuno-assays for detection of antibodies against Hendra virus

Hendra and Nipah viruses (HeV and NiV) are closely related zoonotic pathogens of the Paramyxoviridae family. Both viruses belong to the Henipavirus genus and cause fatal disease in animals and humans, though only HeV is endemic in Australia. In general and due to the acute nature of the disease, agent detection by PCR and virus isolation are the primary tools for diagnostic investigations. Assays for the detection of antibodies against HeV are fit more readily for the purpose of surveillance testing in disease epidemiology and to meet certification requirements in the international movement of horses. The first generation indirect ELISA has been affected by non-specific reactions which must be resolved using virus neutralisation serology conducted at laboratory bio-safety level 4 containment (PC4). Recent developments have enabled improvements in the available serology assays. The production of an expressed recombinant truncated HeV G protein has been utilised in ELISA and in Luminex-based multiplexed microsphere assays. In the latter format, two Luminex assays have been developed for use in henipavirus serology: a binding assay (designed for antibody detection and differentiation) and a blocking assay (designed as a surrogate for virus neutralisation). Equine and canine field sera were used to evaluate the two Luminex assays relative to ELISA and virus neutralisation serology. Results showed that Luminex assays can be effective as rapid, sensitive and specific tests for the detection of HeV antibody in horse and dog sera. The tests do not require PC4 containment and are appropriate for high throughput applications as might be required for disease investigations and other epidemiological surveillance. Also, the results show that the Luminex assays detect effectively HeV vaccine-induced antibodies.

Chicken functional genomics: an overview

Chickens have undergone intensive selection to produce highly productive strains with excellent growth rates and feed conversion ratios. There does not appear to be any reduction in the rate of strain improvement. The recently completed chicken genome sequencing project and adjunct projects cataloging single nucleotide polymorphisms demonstrate that there is still a high level of genetic variation present in modern breeds. The information provided by genome and transcriptome studies furnishes the chicken biologist with powerful tools for the functional analysis of gene networks. Gene microarrays have been constructed and used to investigate gene expression patterns associated with certain production traits and changes in expression induced by pathogen challenge. Such studies have the potential to identify important genes involved in biological processes influencing animal productivity and health. Fundamental regulatory mechanisms controlled by non-coding RNAs, such as microRNAs, can now be studied following the identification of many potential genes by homology with previously identified genes from other organisms. We demonstrate here that microarrays and northern blotting can be used to detect expression of microRNAs in chicken tissue. Other tools are being used for functional genomic analysis including the production of transgenic birds, still a difficult process, and the use of gene silencing. Gene silencing via RNA interference is having a large impact in many areas of functional genomics and we and others have shown that the mechanisms needed for its action are functional in chickens. The chicken genome sequence has revealed a large number of immune related genes that had not previously been identified in chickens. Functional analysis of these genes is likely to lead to applications aimed at improving chicken health and productivity.

Granulocyte colony-stimulating factor given to donors before apheresis does not prevent aplasia in patients treated with donor leukocyte infusion for recurrent chronic myeloid leukemia after bone marrow transplantation

We conducted 2 sequential studies of donor leukocyte infusion (DLI) in 26 patients with chronic myeloid leukemia in hematologic relapse after unmodified allogeneic bone marrow transplantation. In the first study, cells for DLI were collected from 13 donors who were not treated with granulocyte colony-stimulating factor (G-CSF) (group 1). In the second study, cells were collected from 13 donors who received G-CSF before apheresis (group 2) in an attempt to avoid aplasia after DLI. Patients in group 2 received 550-fold more CD34+ cells than those in group 1. We found no significant difference in the incidence (31% versus 22%), onset time (41 vs. 48 days), or duration (15 vs. 14 days) of cytopenia after DLI in the 2 groups. G-CSF given to donors before collection of cells did not prevent aplasia. These findings support the hypothesis that the pathogenesis of aplasia after DLI is not restricted to the destruction of recipient hematopoietic cells but also involves failure of donor hematopoiesis by undefined mechanisms.

Safety and immunogenicity of the Towne strain cytomegalovirus vaccine

BACKGROUND

Women with naturally acquired serum antibodies to cytomegalovirus (CMV) are usually protected against both frequent secondary infection and giving birth to infants severely affected by intrauterine CMV infection.

OBJECTIVE

To determine the feasibility of using a live attenuated strain of CMV (Towne) to achieve immunity similar to that provided by wild-type infection, we evaluated a new lot of the Towne strain of CMV in 3 open label trials involving 68 men, 63 women of childbearing age and 13 children, respectively.

RESULTS

Mild local reactions occurred among approximately one-third of subjects. There were no systemic reactions. All 45 subjects tested developed lymphoproliferative responses to CMV. CD8+ class I-restricted cytotoxic T cell responses specific for CMV antigens were detected in three of four subjects and persisted for 6 months. Neutralizing titers were maximal at 2 to 4 months postimmunization, were dose-dependent and were comparable to those induced by natural infection.

CONCLUSION

These results support further evaluation of the Towne strain of CMV in women at risk for acquiring CMV infection during pregnancy or among children transmitting CMV to pregnant women.

Intrapatient sequence variation of the gag gene of human immunodeficiency virus type 1 plasma virions

Because certain regions of the gag gene, such as p24, are highly conserved among human immunodeficiency virus (HIV) isolates, many therapeutic strategies have been directed at gag gene targets. Although intrapatient variation of segments of gag have been determined, little is known about the variability of the full-length gag gene for HIV isolated from a single individual. To evaluate intrapatient full-length gag variability, we derived the nucleotide sequences of at least 10 cDNA gag clones of virion RNA isolated from plasma for each of four asymptomatic HIV type 1-infected patients with relatively high CD4+ T-cell counts (300 to 450 cells per mm3). Mean values of intrapatient gag nucleotide variation obtained by pairwise comparisons ranged from 0.55 to 2.86%. For three subjects, this value was equivalent to that reported for intrapatient full-length env variation. The greatest range of intrapatient mean nucleotide variation for individual protein-coding regions was observed for p7. We did not detect any G-to-A hypermutation, as A-to-G and G-to-A transitions occurred at similar frequencies, accounting for 29 and 25%, respectively, of the changes. Mean variation values and phylogenetic analysis suggested that the extent of nucleotide variation correlated with the length of viral infection. Furthermore, no distinct subpopulations of quasispecies were detectable within an individual. The predicted amino acid sequences indicated that there were no regions within a gag protein that were comprised of clustered changes.

High-dose cytarabine and total body irradiation with or without cyclophosphamide as a preparative regimen for marrow transplantation for acute leukemia

Twenty-nine patients were conditioned for allogeneic marrow transplant with cytarabine (ara-C) (3 g/m2 every 12 hours for 12 doses) and total body irradiation (TBI) (200 cGy daily for six days) with or without cyclophosphamide (CY) (60 mg/kg) to determine toxicity and efficacy. Four patients had chronic myelogenous leukemia (CML) in accelerated phase or blast crisis, and 25 patients had acute leukemia, 24 at stages later than first remission. Three patients (10%) had fatal regimen-related toxicity and another 10% experienced severe toxicity in at least one organ system. The addition of CY to the ara-C and TBI regimen was not associated with an increase in the frequency of severe toxicity. Twenty-five of 29 patients engrafted eight to 33 days posttransplant: three died early before engraftment, and one patient failed to engraft. Ten of 29 patients are alive without disease, and the actuarial probability of disease-free survival for the entire group at 3 years is 33%. Three of ten patients with acute nonlymphocytic leukemia (ANL), six of 15 with acute lymphocytic leukemia (ALL), and one of four with CML are alive and disease free 25 to 42 months (median, 30 months) after transplant. High-dose ara-C (HDara-C) and TBI with or without CY can be administered with approximately the same toxicity as CY plus TBI. Phase III studies appear warranted to determine if these newer regimens provide improved results compared with currently used regimens.

Colonization with slime-positive coagulase-negative staphylococci as a risk factor for invasive coagulase-negative staphylococci infections in neonates

Mucocutaneous cultures obtained at admission and subsequent weekly nasopharyngeal cultures were obtained on 182 infants in the neonatal intensive care unit (NICU) over 3 months to assess whether a relationship existed between colonization with coagulase-negative staphylococci and invasive infection, particularly with respect to slime production. Nasopharyngeal colonization by coagulase-negative staphylococci occurred in a mean of 58% of infants weekly, with an equal prevalence of slime-positive and slime-negative isolates over time. Colonization of the nasopharynx on admission increased from 8.9% of those admitted within the first day of life to 33% of those admitted thereafter (p less than 0.005). The presence of slime-positive coagulase-negative staphylococci on admission was not predictive of later patterns of colonization with respect to slime. Of infants not colonized on admission who had subsequent cultures, 72% became colonized with coagulase-negative staphylococci that were equally likely to be slime-positive or slime-negative. The incidence of invasive infections was 4.4%. Infants with slime-positive mucocutaneous colonization were more likely to develop invasive coagulase-negative staphylococci disease than infants with slime-negative or no colonization (8.4% versus 1.1%; p less than 0.025). The incidence of slime-positive coagulase-negative staphylococci isolates from blood cultures was 6/7 (86%) whereas those from mucocutaneous cultures was 131/260 (50%) (p = 0.06). Colonization with slime-positive coagulase-negative staphylococci is a significant risk factor for developing invasive coagulase-negative staphylococci disease and these organisms are responsible for the majority of coagulase-negative staphylococci invasive infections.

The double gammopathies. Clinical and immunological studies

A retrospective review of 1135 patients with paraproteinemias recorded 28 (2.5%) as having two M components. This group included 11 patients with myeloma, 6 with lymphoproliferative disease, 5 with a nonlymphoproliferative malignancy, and 6 with a double gammopathy of undetermined significance. In 13 cases in which the M components were measured over a period of time, three distinct patterns were observed, which may reflect the cellular and subcellular origin of the two proteins: 1) In 2 cases the minor component remained relatively stable while the dominant protein changed with time and treatment, suggesting the origin to be two cell lines--the minor arising from a quiescent clone of the monoclonal gammopathy of undetermined significance, and the major M component arising from a more rapidly proliferating plasma cell line; 2) a discordant pattern was seen in 4 patients, suggesting that the two M components arose from two separate plasma cell clones; 3) seven cases in which the proteins behaved in a concordant manner probably arose from a single plasma cell clone with incomplete class switching, producing two M components with different heavy chains.

The treatment resistance of lymphocyte depleted Hodgkin's disease

Lymphocyte-depleted Hodgkin's Disease (LDHD) is a very aggressive form of cancer that presents at an advanced stage and for which no increase in overall survival has been demonstrated with the advent of multiple agent chemotherapy. All cases of Hodgkin's disease diagnosed in the Province of Manitoba between 1971 and 1977 were reviewed. Those cases identified as LDHD were reviewed by a single pathologist, and data was abstracted to obtain a clinical profile. Survival curves were constructed comparing the LDHD group to those with other types of Hodgkin's disease. The LDHD group was also compared with an earlier LDHD group treated with single agent chemotherapy in the 1960s. The LDHD group had a significantly shortened survival compared with the other histologies. This was just as significant when mixed cellularity Hodgkin's was compared with LDHD and matched for Stage B symptomatology. Furthermore, there was no difference in survival between the earlier LDHD groups treated with single agent chemotherapy and the later group treated with multiple agent chemotherapy.