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  • Author or Editor: Sagar M. Goyal x
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Abstract

Objective—To examine clinical signs, virus infection and shedding, and transmission of swine influenza virus (SIV) subtype H1N2 among seropositive pigs.

Animals—Eighteen 3-week-old pigs with maternal antibodies against SIV subtypes H1N1, H3N2, and H1N2.

Procedure—Ten pigs (principal) were inoculated intranasally with subtype H1N2 and 2 groups of contact pigs (n = 4) each were mixed with principal pigs on day 7 (group 1) or 28 (group 2). Two principal pigs each were necropsied on days 4, 14, 21, 28, and 42 days after inoculation. Four pigs in each contact group were necropsied 35 and 14 days after contact. Virus excretion was evaluated after inoculation or contact. Lung lesions and the presence of SIV in various tissues were examined.

Results—Mild coughing and increased rectal temperature were observed in principal pigs but not in contact pigs. Nasal virus shedding was detected in all principal pigs from day 2 for 3 to 5 days, in group 1 pigs from day 2 for 4 to 9 days after contact, and in group 2 pigs from day 4 for 2 to 6 days after contact. Trachea, lung, and lymph node specimens from infected pigs contained virus. Antibody titers against all 3 subtypes in all pigs gradually decreased.

Conclusions and Clinical Relevance—Protection from viral infection and shedding was not observed in pigs with maternal antibodies, but clinical disease did not develop. Vaccination programs and good management practices should be considered for control of SIV subtype H1N2 infection on swine farms. ( Am J Vet Res 2004;65:303–306)

Full access
in American Journal of Veterinary Research

Summary

The use of an elisa that can differentiate between swine infected with pseudorabies virus (prv) and swine vaccinated with a specific prv vaccine was evaluated on an individual and herd basis, and a system for interpreting elisa results on a herd basis was developed. In 17 herds, recently introduced replacement gilts, seronegative for prv, were vaccinated with a thymidine kinase- and glycoprotein X (gpX)-deleted vaccine. After vaccination, blood samples were collected from these gilts approximately every 1 to 2 months for up to 19 months. Serum samples were analyzed for antibodies to gpX antigen, using a commercially available elisa kit according to the manufacturer's protocol. Herd status was determined as positive, suspect, or negative, according to the serum sample:negative control (s:n) values of the samples collected from the herd. From the 17 herds, 130 evaluations were performed. On 49 (38%) of the 130 herd evaluations, 1 or more gilts had suspect test results. Additional testing was required in 19 (39%) of these 49 herd evaluations to determine the prv infection status of the herd. Status of herds having gilts with suspect results and no positive results was usually negative after retesting. Herds having gilts with positive results were unlikely to have negative status after retesting.

Free access
in Journal of the American Veterinary Medical Association

SUMMARY

A field strain (87-8363) of bovid herpesvirus-4 (bhv-4) isolated from an aborted bovine fetus was used to inoculate pregnant rabbits. Eleven rabbits in midgestation were alloted to 4 groups consisting of 3 infected groups and 1 control group. Rabbits were inoculated with bhv-4 or mock-infected cell culture preparations via iv, intravaginal, and intrauterine routes. Mild vulvovaginitis and endometritis were observed after intravaginal and iv inoculation of bhv-4, whereas intrauterine inoculation of bhv-4 resulted in abortion of hemorrhagic fetuses and nonsuppurative endometritis. Virus was successfully isolated from organ explants of fetal tissues. Rabbits seroconverted 1 week after infection as detected by results of an indirect immunofluorescence assay.

Free access
in American Journal of Veterinary Research

SUMMARY

Clinicopathologic manifestations of induced infection of the feline lower urinary tract with bovid herpesvirus-4 (bhv-4, strain FCAHV) were characterized in 6 conventionally reared adult cats (2 sexually intact males, 2 castrated males, and 2 females). Two additional control cats were exposed with noninfected cell culture control inoculum. Clinical and radiographic signs of lower urinary tract disease were not observed in exposed or control cats. Microscopic hematuria was detected in urine samples collected by cystocentesis from 4 of 6 exposed cats and 1 of 2 control cats. Results of culture of urine for bacteria, maycoplasmas, ureaplasmas, and viruses were consistently negative. Low titer of serum bhv-4 (strain FCAHV)- neutralizing antibodies was detected in 4 of 6 exposed cats, but not in controls.

Gross abnormalities of the urinary tract were not observed in any cat. Light microscopic examination of serial sections of the lower urinary tract revealed mild focal lymphoid cystitis in 2 of 6 exposed cats, one of which also had increased amounts of connective tissue and proliferation of blood vessels in the urinary bladder lamina propria. Ninety days after initial exposure, bhv-4 (strain FCAHV) was reisolated from explanted urinary bladder tissues of 5 of 6 exposed cats. Virus was not isolated from tissues of control cats.

It was concluded that bhv-4 (strain FCAHV) establishes persistent urinary tract infection in conventionally reared adult male and female cats. However, persistent bhv-4 infection in cats may remain clinically inapparent.

Free access
in American Journal of Veterinary Research

Summary

The clinicopathologic manifestations of bovid herpesvirus-4 (bhv-4; FCAHV strain)-induced infection of the lower portion of the urinary tract were characterized in 12 adult neutered male and 6 female specific-pathogen-free cats, and were compared with those in 12 neutered male control cats. Six neutered male and 6 female cats were given immunosuppressive doses of methylprednisolone acetate prior to inoculation of their urinary bladders with bhv-4. Six neutered male control cats were given immunosuppressive doses of methylprednisolone acetate prior to inoculation of their urinary bladders with uninfected tissue culture control inoculum. Six additional neutered male control cats were exposed only to uninfected tissue culture control inoculum. All cats were observed for 90 days following inoculation. Dysuria and gross hematuria were observed in only 1 bhv-4-exposed cat. Radiographic abnormalities of the lower portion of the urinary tract were not observed. Microscopic hematuria, crystalluria, and lipiduria were identified with similar frequency in bhv-4-exposed and control cats. Results of urine culturing for bacteria, mycoplasma, ureaplasma, and viruses were negative. Viruses were not isolated from blood leukocytes collected from exposed or control cats. Three to 6 weeks after inoculation, high concentrations of bhv-4 serum antibodies were detected in all exposed cats by an indirect fluorescent antibody test.

Light microscopic examination of the urinary tract revealed multifocal lymphoid cystitis in 2 bhv-4-exposed cats. Except for suppurative bronchitis in 1 bhv-4-exposed cat given glucocorticoids, morphologic differences in urinary and extraurinary tissues were not observed. In urinary bladder tissue collected 90 days after inoculation, bhv-4 was reisolated from urinary bladder explants of all but 1 exposed cat. Virus was also isolated from a kidney explant of 1 exposed male cat, and spleen cell cocultures of 1 exposed female cat given glucocorticoids.

Bovid herpesvirus-4 (FCAHV strain) caused persistent urinary tract infections in male and female specific-pathogen-free cats. Detection of occult bhv-4 infection required isolation of virus from tissues by explantation, or demonstration of specific bhv-4 antibodies by immunofluorescent techniques. Administration of glucocorticoids prior to inoculation did not enhance morbidity associated with bhv-4 urinary tract infection. Further investigations are needed to determine the pathogenic role of bhv-4 in noninduced feline lower urinary tract disease.

Free access
in American Journal of Veterinary Research

Summary

In a prospective study, 141 cats with hematuria, dysuria, urethral obstruction, or combinations of these signs were evaluated by contemporary diagnostic methods and compared with 26 clinically normal cats (controls). Specific diagnosis was established in 45% (64/141) of cats affected with lower urinary tract disease (lutd). Crystalline matrix plug-induced urethral obstruction was diagnosed in 21% (30/141) of affected cats, uroliths were identified in 21% (30/141) of affected cats, uroliths with concomitant bacterial urinary tract infection (uti) were identified in < 2% (2/141) of affected cats, and bacterial uti alone was identified in < 2% (2/141) of cats with lutd. Viruses, mycoplasmas, and ureaplasmas were not isolated from urine samples collected from affected or control cats.

Bovine herpesvirus 4 (bhv-4)-neutralizing antibodies were not detected in any serum sample obtained from cats with lutd or from control cats. In contrast, bhv-4 antibodies were detected by an indirect immunofluorescent antibody (ifa) test in sera obtained from 31% (44/141) of cats with lutd and 23% (6/26) of control cats. The prevalence of positive bhv-4 ifa test results in affected cats was not significantly different from that observed in control cats. Significant association was not apparent between positive bhv-4 ifa test results and clinical diagnosis, abnormal laboratory findings, or cat age. However, the number of male cats with bhv-4 ifa titer was significantly (P < 0.02, χ2 test) greater than that of female cats. Detection of bhv-4 antibodies in approximately 30% of affected and control cats indicates prior virus exposure. Further investigations are warranted to clarify the specific role of bhv-4 in cats with naturally acquired lutd.

Free access
in Journal of the American Veterinary Medical Association