We evaluated the efficacy of acyclovir against experimentally induced herpesvirus infection (Pacheco's parrot disease) in Quaker parakeets. Thirty-two of 40 birds were challenge-exposed with 0.1 ml of a suspension of herpes-virus (10(4) median cell culture infective doses CCID50 ) given IM. Treatment with acyclovir was started 24 hours later and was continued for 7 days. The birds were allotted to 5 groups of 8 birds each. There was a considerable difference in mortality between groups 1-5. Of 8 birds in each group, 6 died in group 1 (control), 1 died in group 2 (gavage), 3 died in group 3 (low dose, IM), 4 died in group 4 (high dose, IM), and none died in group 5 (contact controls). There was a significant (P = 0.023) difference in mortality between groups 1 and 2, thus the oral form of acyclovir administered by gavage was the most efficacious therapeutic regimen. Clinical signs and death occurred after discontinuation of acyclovir in groups 2 and 3, whereas the mean time of death for the control group was 6 days after challenge exposure. Herpesvirus was recovered by inoculation of chick embryo cell culture with pooled tissue suspensions from all birds that died. Histologic evidence of herpesvirus infection was found in most birds that died, with the control group having the most severe lesions. Surviving Quaker parakeets were transferred to cages with seronegative Quaker parakeets with no known exposure to herpesvirus. There have been no deaths attributable to herpesvirus infection in a period exceeding 2 years.

Objective-To assess the biological response to recombinant feline interferon-omega (rFeIFN-omega) following ocular or oral administration in cats via estimation of Mx protein expression in conjunctival cells (CCs) and WBCs. Animals-10 specific pathogen-free cats. Procedures-In multiple single-dose drug experiments, each cat received various concentrations of rFeIFN-omega administered topically into both eyes (50 to 10,000 U/eye) and orally (200 to 20,000 units). The same cats received saline (0.9% NaCl) solution topically and orally as control treatments. The CCs and WBCs were collected prior to treatment (day 0), on day 1, and every third or seventh day thereafter until samples yielded negative results for Mx protein. Samples were examined for Mx protein expression via immunohistochemistry and immunoblotting procedures involving murine anti-Mx protein monoclonal antibody M143. Results-After topical application of 10,000 U of rFeIFN-omega/eye, CCs stained for Mx protein for a minimum of 7 days, whereas WBCs were positive for Mx protein for a minimum of 31 days. After topical application of lower concentrations, CCs did not express Mx protein, in contrast to WBCs, which stained for Mx protein at 1,000 units for at least 1 day. Following oral administration, Mx protein was expressed in WBCs at rFeIFN-omega concentrations as low as 200 units, whereas CCs did not stain for Mx protein at any concentration. Conclusions and Clinical Relevance-Results indicate that Mx protein expression (a marker of the biological response to rFeIFN-omega) in CCs and WBCs of rFeIFN-omega-treated cats depends on the dose of rFeIFN-omega, site of administration, and cell type.

In vitro activities of 9-([2-hydroxyethoxy] methyl) guanine (acyclovir), (E)-5-(2-bromovinyl)-2'deoxyuridine, 9-beta-D-arabinofuranosyladenine (vidarabine), 5-iodo-2'-deoxyuridine (idoxuridine), and 5-trifluoromethyl-2'-deoxyuridine (trifluridine) were studied against 6 strains of feline herpesvirus-1. A significant difference was not detected among viral strains in their susceptibility to these compounds (P = 0.442). The relative potency of these compounds was trifluridine greater than greater than idoxuridine greater than virdarabine greater than bromovinyldeoxyuridine greater than greater than acyclovir. Concentrations of trifluridine and idoxuridine (0.67 and 6.8 micromole, respectively) required to reduce plaque numbers by 50%, compared with that of controls, were significantly lower (P less than 0.001) than were those of other compounds.

Pseudorabies is a porcine herpesvirus of major importance in the swine industry. Isoprinosine is an immunomodulating drug that has been shown to be beneficial in treating herpesvirus infections. Twenty-four 7-week-old pigs were allotted within litters to 1 of 4 groups: control, isoprinosine (ISO), pseudorabies virus (PRV), or isoprinosine and pseudorabies virus (ISO-PRV). Isoprinosine was administered daily for 16 days to the ISO and ISO-PRV groups (75 mg/kg of body weight/day, PO). Immunity in pigs in the PRV and ISO-PRV groups was challenged with pseudorabies virus (10(5) TCID50 units) on day 4. Rectal temperatures and viral excretion were monitored daily; total and differential leukocyte counts, lymphocyte response to mitogens, and interleukin-2 production were monitored every 4 days. Pigs challenge-inoculated with pseudorabies virus became ill, with the ISO-PRV group most severely affected. Rectal temperatures were high (P less than 0.05) in virally challenged pigs on days 5 to 12 and 14 to 16; isoprinosine did not alter this effect. Pseudorabies virus-infected pigs had leukocytosis (P less than 0.05) on days 12 and 16, primarily caused by neutrophilia. Concanavalin A-stimulated lymphocyte proliferation was decreased (P less than 0.06) in both PRV and ISO-PRV groups on day 12, compared with control pigs, but only in the PRV group on day 16. Pokeweed mitogen-stimulated lymphocyte proliferation was decreased (P less than 0.02) in ISO-PRV pigs on day 8 of the experiment. Interleukin-2 concentrations, pooled over all sampling days, were decreased (P less than 0.03) in pseudorabies virus-infected pigs. Viral excretion was not altered by isoprinosine treatment. These data suggest that pseudorabies virus infection decreased lymphocyte proliferative responses and interleukin-2 prodcution in pigs, and that isoprinosine did not mitigate these effects.

Phosphonoformate (PFA), a noncompetitive inhibitor of reverse transcriptase (RT), inhibited feline leukemia virus FeLV) infection of 2 feline cell lines and inhibited progeny virus RT activity in a chronically FeLV-infected cell line. Feline leukemia virus infection of 3201 cells, an FeLV-negative lymphoma cell line, was inhibited by > 70% at a concentration of only 1 micromole PFA and by > 90% at concentrations of 64 to 256 micromole PFA, as evidenced by RT activity. However, FeLV antigen expression by 3201 cells remained relatively constant over noncytotoxic concentrations of PFA. Because the persistence of viral antigen expression with concomitant suppression of RT activity appears to be unique and because 3201 cells express small amounts of an endogenous retrovirus (RD and 114) contain endogenous FeLV proviral sequences, a possible role of endogenous retroviruses acting as helper viruses was suggested. Feline leukemia virus infection of 81C cells, a sarcoma-positive, leukemia-negative fibroblast cell line, was inhibited by > 50% at a concentration of 64 micromole PFA and by > 98% at concentrations of 256 to 512 micromole PFA, as indicated by suppression of focus formation. The feline lymphoid cell line FL-74 is a large producer of FeLV. When FL-74 cells were cultured in the presence of 256 micromole PFA, virus production (virus budding and viral antigen) was not affected, but progeny virus lost RT activity and infectivity. Direct addition of PFA (256 micromole to FeLV also reduced RT activity and infectivity. These data indicate that PFA can directly and rapidly inactivate retrovirus independent of cellular processing, presumably by inhibiting RT. Long-term PFA administration may curtail spread of retroviral infections within and between hosts via extracellular inactivation of newly produced virus particles. Results of this study also suggest that PFA might be used prophylactically to treat materials potentially contaminated with retroviruses.

Studying of palatability of bait blisters applied for oral immunization of wild carnivores against rabies was realized in the conditions of the Republic of Belarus by an example of foxes which were administrated with liquid viral vaccines against rabies. Foxes were divided into 5 groups with 8 animals in each. Animals of the first group were immunized with a liquid viral vaccine in blister baits Lisvulpen-VBF which was produced from an attenuate strain of rabies virus SAD-BERN (Belarus). Animals of the second group were immunized with liquid viral vaccine Belvak TM BP produced from the cultural living strain KMIEhV-V101 (Belarus). Animals of the rest three groups were immunized with liquid viral vaccine in blister baits which was produced from a modified strain of a fixed attenuate rabies virus KMIEV-94. Foxes of the forth group were additionally fed with ascorbic acid with baits in the doze of 0,1 g, and foxes of the fifth group were fed with 5 ml immune response modifier Nuklevit. All mentioned blister baits were studied in accordance with the following parameters: bait flavor and attraction to animals; form and size of bait; bait consistency; blister and its size in relation to bait; palatability of bait; degree of damage of bait containing a vaccine; quantity vaccine which was got into animal oral cavity; postvaccinal complication. Palatability of liquid viral vaccines in blister baits Lisvulpen-VBF was 96%, Belvak TM BP - 94%, KMIEV-94 - 80%

In the conditions of the Republic of Belarus by means of application of a scanning electron microscopy there was realized a morphological assessment of the efficiency of mono- and associated antiviral vaccines. It is shown, that analyzed biological preparations invoke in poultry a number of structural disorders among which it is possible to mention both immunomorphological changes, and pathomorphological processes. The highest reactogenicity was showed by of monovaccines against infectious bronchitis (produced by Research Institute of Animal Protection, Russia); infectious laryngotracheitis (Institute of Experimental Veterinary of S.N.Vyshelesskij, Belarus); and also an associated vaccine against infectious bronchitis, infectious bursal disease and Newcastle disease (Research Institute of Animal Protection, Russia). These vaccines caused essential structural disorders in tissues at a place of administration, liver and kidneys. Administration of the vaccine against infectious bursal disease and associated vaccines against infectious bronchitis, infectious bursal disease, infectious laryngotracheitis and Newcastle disease (Institute of Experimental Veterinary of S.N.Vyshelesskij) strengthened the processes of lymphatization in fabricic bursa. All studied biological products caused activization of morphological reorganization of immune apparatus of a spleen and did not render essential influence on thymus structure. | С использованием сканирующей электронной микроскопии проведена морфологическая оценка эффективности моно- и ассоциированных противовирусных вакцин. Показано, что указанные биопрепараты вызывают в организме птиц ряд структурных нарушений, среди которых можно выделить как иммуноморфологические изменения, так и патоморфологические процессы. Наибольшую реактогенность проявляли моновакцины против инфекционного бронхита кур (ФГУ ВНИИЗЖ, Россия), инфекционного ларинготрахеита (ИЭВ им. С.Н. Вышелесского), а также ассоциированная вакцина против ИБК, инфекционной бурсальной болезни и болезни Ньюкасла (ФГУ ВНИИЗЖ, Россия), которые вызывали существенные структурные нарушения в ткани на месте введения, печени и почках. Использование вакцины против ИББ и ассоциированной вакцины против ИБК, ИББ, ИЛТ и БН (ИЭВ им. С.Н. Вышелесского) усиливало процессы лимфатизации в фабрициевой бурсе. Все изучаемые биопрепараты вызывали активизацию морфологической перестройки иммунного аппарата селезенки и не оказывали существенного влияния на структуру тимуса.