Aspectos virológicos e clínico-patológicos da infecção genital aguda e latente pelo herpesvírus bovino tipo 1.2 em bezerras infectadas experimentalmente

Abstract

2) may result in vulvovaginitis and transient infertility. The acute infection is followed by the establishment of latent infection which can be periodically reactivated. We herein describe the virology and clinico-pathological aspects of acute and recrudescent vulvovaginitis in heifers inoculated with a Brazilian BoHV-1.2 isolate recovered from an outbreak of balanoposthitis. Genital inoculation of isolate SV-56/90 (10 8.1 TCID 50 / animal) in four eight-months-old heifers resulted in efficient virus replication in the genital mucosa and the development of moderate to severe vulvovaginitis. The inoculated heifers shed virus in genital secretions in titers up to 10 7.3 TCID 50 /mL until day 10 pi and developed genital congestion, swelling, vesicles and pustules. The vesicles and pustules increased in size eventually coalesced and became covered with a yellowish exsudate. These signs appeared at day 2 pi, increased in severity up to days 5 -8 pi and progressively subsided thereafter. Dexamethasone administration at day 55 pi resulted in virus shedding in vaginal secretions for up to 10 days. Virus reactivation in all animals was accompanied by clinical recrudescence of the disease, yet less severe than during acute infection. Examination of sacral ganglia and lymph nodes by PCR at day 36 postreactivation revealed the presence of latent viral DNA in the pudendal (4/4), genitofemoral, sciatic and rectal caudal (3/4) and obturator nerve ganglia (1/4); in addition to several regional lymph nodes. These results demonstrate the virulence of isolate SV-56/90 for heifers and pave the way for its use in further pathogenesis studies and vaccine-challenge trials.

Genital immunization of heifers with a glycoprotein Edeleted, recombinant bovine herpesvirus 1 strain confers protection upon challenge with a virulent isolate

“…The challenge used in the present study has been designed as to really evaluate the protection conferred by immunization. For this, we used a heterologous BoHV-1.2 isolate previously shown to be highly virulent for bulls (Vogel et al 2004) and heifers (Henzel et al 2008), in a titer unlikely to be found in raw semen of infected bulls (Vogel et al 2004) or in semen used for artificial insemination (AI) (Van Engelenburg et al 1995). Furthermore, the virus suspension was applied by vigorous swabbing against the mucosa to assure efficient infection.…”

“…The virus used for challenge (SV-56/ 90) was isolated from an outbreak of balanoposthitis in bulls in Southern Brazil (Weiblen et al 1992) and subsequently characterized as belonging to BoHV-1.2 subtype (D'Arce et al 2002). The virulence of this isolate has been demonstrated after intrapreputial inoculation of bulls (Vogel et al 2004) and following intravaginal inoculation of heifers (Henzel et al 2008).…”

Viral main causes of abortion in cattle

“…Assim, a infecção latente e posterior reativação explicam a persistência do vírus e o aparecimento de novos casos clínicos no rebanho ao longo do tempo. A infecção latente pelo BHV-1.2 em fêmeas tem sido pouco estudada e vários aspectos da patogenia permanecem não esclarecidos (HENZEL et al, 2008).…”