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Background: The binding of viral-specific antibodies to cell-surface antigens usually results in down modulation of the antigen through redistribution of antigens into patches that subsequently may be internalized by endocytosis or may form caps that can be expelled to the extracellular space. Here, by use of confocal-laser-scanning microscopy we investigated the kinetics of the modulation of respiratory syncytial virus (RSV) antigen by RSV-specific IgG. RSV-infected human epithelial cells (HEp-2) were incubated with anti-RSV polyclonal IgG and, at various incubation times, the RSV-cell-surface-antigen-antibody complexes (RSV Ag-Abs) and intracellular viral proteins were detected by indirect immunoflourescence.

Oncolytic viruses, either naturally or genetically modified, possess the ability to kill cancer cells. Newcastle Disease Virus (NDV), a type I avian paramyxovirus, has demonstrated a selective ability to kill cancer cells directly as well as through immunostimulation. NDV is able to infect more than 250 species of birds, particularly poultry and is considered a zoonosis, primarily causing conjunctivitis. Importantly, no infections have been reported in mammalian species nor is there evidence of human to human transmission. We use the LaSota strain which is lentogenic (less pathogenic). We seek to study the in vitro oncolytic (lympholytic) potential of NDV on healthy mononuclear and malignant lymphocytes and the in vivo oncolytic therapeutic potential in dogs with lymphoma. LaSota vaccine strain (LSV) was propagated in pathogen –free 9 day old chicken embrios. Viral titers were reported as mean infective dose. Healthy human and canine mononuclear cells as well as a human diffuse large B cell lymphoma cell line (DHL4 cell line) were exposed to medium alone, LSV at a multiplicity of infection (MOI) of 0.1, 10 and 100 or CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone) chemotherapy. Apoptosis was assessed by flow cytometry using annexin V/FITC/IT. Cell counts were carried out at 48 and 72 hs. Data was analyzed by FlowJo 9 and Prisma 6 Softwares. Interestingly, cells at the highest MOI (100) had the same rate of apoptosis as those exposed to chemotherapy, both significantly higher than negative controls. The in vivo response and toxicity to intravenous and intratumoral inyection of LSV in a dog with naturally occurring aggressive, multicentric cutaneous T-cell lymphoma is reported. The patient had a 4 week history of paraplegia due to lymphomatous infiltration of the spinal canal and a 3 week history of rapid development of multiple elevated cutaneous lesions ranging from (from 0.5 by 0.5 cm to 15 cm in diameter and 2 cm in thickness). After informed consent, LSV was given in a single occasion with 1x106 mean (50%) infective dose in tissue culture (TCDI 50) in only one lesion, as well as intravenously with a TCDI 50 of 1x1012 in order to assess response of distant non-virally infiltrated lesions. At four weeks of follow up, no new lesions have appeared. All tumors are responding with complete flattening of the lesions and decrease in diamenter of all lesions. Spontaneous bleeding from the lesions was seen from days 4 through 7 after treatment. All laboratory work up is within normal limits except for indirect hiperbilirrubinemia (2x above normal) in the 4th week (Coombs results are pending). Consecutive samples for histology, electron microscopy and viral load are being evaluated. The patient has had an excellent performance status with no evident clinical toxicity and has begun to wag his tail and show slow movement of the posterior limbs with gain in sensitivity. We have demonstrated the specific in vitro, oncolytic/lympholytic activity of NCV (LaSota) on human lymphoma- derived cells with minimal tropism towards healthy cells. Response to treatment of the first patient (dog) is encouraging. Longer follow up as well as histologic evaluation and viral shedding are being evaluated. Disclosures No relevant conflicts of interest to declare.

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Eighty-three wild and domestic carnivores of nine species from Janos Biosphere Reserve (JBR), Mexico, were tested by serologic and molecular assays to determine exposure and infection rates of carnivore protoparvovirus 1. Overall, 50.8% (33/65) of the wild carnivores and 100% (18/18) of the domestic dogs tested were seropositive for Canine protoparvovirus 1 (CPV), while 23% (15/65) of the wild carnivores and 22.2% (4/ 18) of the domestic dogs were PCR positive for CPV. Phylogenetic analysis confirmed circulation of CVP-2 with residues 426 Asn (CPV2a = 1/19) and 426 Glu (CPV-2c = 18/19) among carnivores in JBR. The prevalence of both PCR positivity and antibodies to CPV varied significantly among wild host species. Of the six identified haplotypes, three were unique to kit foxes (Vulpes macrotis) (the species with higher haplotype richness) and two to striped skunks (Mephitis mephitis). The remaining haplotype was shared among all carnivore species including dogs suggesting non-host specificity and bidirectional and continuous viral transmission cycle in the JBR. The phylogenetic similarity of CPV strains from dogs and wild carnivores and the higher prevalence of CPV in wild carnivores captured near towns relative to those captured far from towns suggest that dogs might be an important source of CPV infection for wild carnivores in the JBR. We provide evidence that cross-species transmission occurs at the domestic-wildlife interface in JBR.