Serological survey of bovine herpesvirus type 1 infection in China

To understand the nationwide seroprevalence of bovine herpesvirus type 1 (BoHV-1) infection of cows in China, 1344 sera of dairy cows from 29 provinces and 765 sera from 6 herds in Hubei province were collected with stratified random sampling. Another 483 sera from imported cows were included. The serum antibody was tested by BoHV-1 gG ELISA. The results demonstrated that the overall nationwide seroprevalence was 35.8% (481/1344), while the prevalence for individual province ranged from 12.1% to 77.8%. Although each province had positive samples, the prevalence was clustered in areas based on the cow population size. In Hubei Province, the overall seroprevalence was 22.2% (170/765) while the prevalence for individual farms varied greatly from 0.0% to 41.5%. The sera from imported cows had a moderate prevalence of 21.7% (105/483).     

Characterization of Bovine herpesvirus type 4 isolated from cattle with mastitis and subclinical infection by the virus among cattle

An outbreak of contagious mastitis occurred among cattle on a farm, and bovine herpesviruses were isolated from the affected mammary tissues, scabs and abscess discharge of the cattle. A bovine herpesvirus type 4 (BoHV-4)-specific fragment was amplified from the isolates by polymerase chain reaction (PCR). Restriction endonuclease analyses demonstrated that the isolates were related to Movar-like European type BoHV-4. To determine the ratio of BoHV-4 subclinical infection in the cattle, a genomic survey was performed by PCR for cattle that were moved to the animal hygiene service station in Ibaraki prefecture. The BoHV-4 genome was occasionally detected in peripheral blood leukocytes, lymph nodes and nervous tissues. The rate of BoHV-4 subclinical infection was relatively high in the cattle.     

Latency and persistence of bovine herpesvirus type 4, strain B11-41, in bovine nervous tissues

Three cattle were experimentally infected with bovine herpesvirus type 4 (BoHV-4), strain B11-41, isolated from the spinal cord of a cow, and monitored for clinical symptoms. None of them showed any clinical signs except increases of leukocyte numbers in two of them, and the body temperature remained normal throughout the experiment. Antibody titers against BoHV-4 continuously increased for one month and were maintained at a high level for more than 1 year by enzyme-linked immunosorbent assay (ELISA). The virus was isolated only from serum and peripheral blood leukocytes (PBL) of one cow in the early stage of infection, but the viral genome was detected in PBL continuously by PCR. When they were euthanized, the viral genome was detected in the lymph nodes and nervous tissues such as medulla, spinal cord, and trigeminal ganglion. These results indicate that cattle are infected with the virus latently and persistently, and the latency site would be in the tissues of the central nervous system as well as lymphoid tissues. When a seroepidemiological survey was performed on antibodies to BoHV-4 among cattle in Japan by ELISA, the rate of antibody-positive cattle was 8.9% and they were found irregularly on certain farms.     

Orf virus circulation in cattle in Turkey

Orf virus (ORFV) causes contagious skin disease that mainly affects sheep and goats with zoonotic potential. However, there is not enough information about the association between ORFV and occurrence of skin disease in cattle. The present study describes outbreaks of ORFV infection in cattle in different provinces that are located in the Aegean, Central Anatolian and Mediterranean regions of Turkey. During the months of June and August 2017, vesicular fluid and scab samples were collected from cattle which had proliferative skin lesions. First, presence of lumpy skin disease virus (LSDV) and bovine herpesvirus 2 (BoHV-2, known as the causative agent of pseudo-lumpy skin disease) were investigated by real time PCR and PCR, respectively. Then, samples tested for the presence of parapoxviruses by PCR using primers specific to major envelope protein gene (B2L). Parapoxvirus DNA was detected in investigated samples whereas LSDV and BoHV-2 DNA were not detected. The analysis of the B2L gene sequences revealed that cattle were infected with ORFV. The isolates in the present study shared 100% sequence identity at the nucleotide and amino acid level when compared with previously characterised Turkish field ORFV isolates from goats in 2016. Results of the study show unusual infection of cattle with ORFV, and suggest that ORFV jumps the host species barrier from goats to cattle.     

The recent prevalence of bovine leukemia virus (BLV) infection among Japanese cattle

A seroepidemiological survey of bovine leukemia virus (BLV) infection was conducted in Japan in 2007 using an enzyme-linked immunosorbent assay (ELISA) and an agar gel immunodiffusion (AGID) test. A total of 5420 cattle (dairy, 3966; breeding beef, 797; fattening beef, 657) from 209 farms in seven prefectures in Japan were tested. The overall prevalence of BLV infection was 28.6%. The prevalence of BLV infection in dairy cattle (34.7%) was higher than for both fattening beef cattle (7.9%) and breeding beef cattle (16.3%). Age-specific prevalence showed that BLV prevalence increased with age in all types of cattle and was notably different between dairy and beef cattle under 1 year of age. Among 207 farms, 141 herds (68.1%) had one or more positive animals. The proportion of these positive farms was significantly higher among dairy farms (79.1%) than among beef breeding farms (39.5%) and beef fattening farms (51.9%) (P < 0.001). Dairy farms (40.5%) also showed a significantly higher within-herd prevalence than beef breeding (27.4%) and fattening (14.9%) farms (P = 0.001). This study indicated that BLV is more widely spread in dairy cattle than in beef breeding cattle in Japan. Given the prevalence of BLV infection in dairy and beef cattle was 8- and 1.7-fold higher, respectively, than rates previously found in 1980–1982, BLV appears to be spreading particularly among the dairy cattle population during the last two decades. Further investigation is required to determine the risk factors necessary to control BLV infection that take into account the different farming practices that exist between dairy and beef sectors.     

Seroprevalence of bovine immunodeficiency virus and bovine leukemia virus in dairy and beef cattle in hokkaido

Serological survey of bovine immunodeficiency virus (BIV) and bovine leukemia virus (BLV) infection was conducted in dairy cattle from 10 different regions of Hokkaido, Japan. Among 390 cattle, 11.0% of cattle were BIV-seropositive and 3.3% were BLV-seropositive. Moreover, in two dairy farms, where bovine leukosis has been reported, prevalence of BIV infections were 6.4 and 9.1%, respectively. In contrast, among 150 beef cattle, 16.6% were BIV-seropositive while none was BLV-seropositive. Dual infections with BLV and BIV in dairy cattle were tested by using 107 BLV-seropositive sera, and 20 sera were found BIV-positive (18.7%). These results indicate that BIV infection was widespread in Hokkaido.     

Should the domestic buffalo (Bubalus bubalis) be considered in the epidemiology of Bovine Herpesvirus 1 infection?

Only limited information is available on the epidemiology and pathogenesis of Bovine Herpesvirus 1 (BoHV-1) in domestic buffalos. In this study, a virulent BoHV-1 field strain isolated from cattle was inoculated into buffaloes to evaluate their susceptibility to the virus and to investigate the establishment of viral latency through clinical, virological and serological investigations. Latency was also studied by attempting viral reactivation using pharmacological induction. Six of seven male, 5 months old buffaloes were intranasally inoculated with BoHV-1; the other animal was kept as negative control. The animals were clinically monitored during the post-infection (P.I.) and the post-pharmacological induction (P.P.) periods. During these periods, nasal and rectal swabs, and blood samples, with and without anticoagulant, were collected at 2–3 day intervals. On culling the animals, 206 days P.I., their trigeminal ganglia and tonsils were collected. No clinical signs referable to BoHV-1 were observed throughout the experimental period. However, seropositivity was detected in all infected animals within day 20 P.I., using BoHV-1 glycoprotein E and glycoprotein B competitive ELISAs (IDEXX) and virus neutralisation test. In real-time PCR (RT-PCR), five of these animals were positive, at least once, for nasal or rectal swabs, during the P.I. period. The sixth infected animal was found positive only in the trigeminal ganglia after culling. Ganglia were also positive for two other animals. Virus isolation in permissive cell-lines was successful for a part of the RT-PCR positive samples. The detected viruses were confirmed by genetic analysis as identical to the inoculated strain. No evidence of infection was observed in the negative control. This study represents the first experimental transmission of BoHV-1 in buffaloes, confirming their susceptibility to infection and their possible role as host/reservoirs of BoHV-1.     

Prevalence of hemoplasma infection among cattle in the western part of Japan

We have examined for hemoplasma infection among cattle in the Hiroshima and Miyazaki prefectures by using a sensitive real-time PCR, with SYBR Green I and with melting curve analysis, which allow to distinguish the two bovine hemoplasma species, Mycoplasma wenyonii and 'Candidatus M. haemobos'. We found 69.4% of 36 cattle in Hiroshima and 93.8% of 32 cattle in Miyazaki infected with either of these two hemoplasma species. High morbidity in western part of Japan may reflect the activity of arthropod vectors for hemoplasma transmission. We also demonstrated neonatal calves less than three months old affected with hemoplasmas without grazing in summer, suggesting a possibility of vertical transmission.     

Efficacy of an inactivated,recombinant bovine herpesvirus type 5 (BoHV-5) vaccine

Bovine herpesvirus type 5 (BoHV-5) is the causative agent of bovine herpetic encephalitis. In countries where BoHV-5 is prevalent, attempts to vaccinate cattle to prevent clinical signs from BoHV-5-induced disease have relied essentially on vaccination with BoHV-1 vaccines. However, such practice has been shown not to confer full protection to BoHV-5 challenge. In the present study, an inactivated, oil adjuvanted vaccine prepared with a recombinant BoHV-5 from which the genes coding for glycoprotein I (gI), glycoprotein E (gE) and membrane protein US9 were deleted (BoHV-5 gI/gE/US9⁻), was evaluated in cattle in a vaccination/challenge experiment. The vaccine was prepared from a virus suspension containing a pre-inactivation antigenic mass equivalent to 10^7.69 TCID₅₀/dose. Three mL of the inactivated vaccine were administered subcutaneously to eight calves serologically negative for BoHV-5 (vaccinated group). Four other calves were mock-vaccinated with an equivalent preparation without viral antigens (control group). Both groups were boostered 28 days later. Neither clinical signs of disease nor adverse effects were observed during or after vaccination. A specific serological response, revealed by the development of neutralizing antibodies, was detected in all vaccinated animals after the first dose of vaccine, whereas control animals remained seronegative. Calves were subsequently challenged on day 77 post-vaccination (pv) with 10^9.25 TCID₅₀ of the wild-type BoHV-5 (parental strain EVI 88/95). After challenge, vaccinated cattle displayed mild signs of respiratory disease, whereas the control group developed respiratory disease and severe encephalitis, which led to culling of 2/4 calves. Searches for viral DNA in the central nervous system (CNS) of vaccinated calves indicated that wild-type BoHV-5 did not replicate, whereas in CNS tissues of calves on the control group, viral DNA was widely distributed. BoHV-5 shedding in nasal secretions was significantly lower in vaccinated calves than in the control group on days 2, 3, 4 and 6 post-challenge (pc). In addition, the duration of virus shedding was significantly shorter in the vaccinated (7 days) than in controls (12 days). Attempts to reactivate latent infection by administration of dexamethasone at 147 days pv led to recrudescence of mild signs of respiratory disease in both vaccinated and control groups. Infectious virus shedding in nasal secretions was detected at reactivation and was significantly lower in vaccinated cattle than in controls on days 11–13 post-reactivation (pr). It is concluded that the inactivated vaccine prepared with the BoHV-5 gI/gE/US9⁻ recombinant was capable of conferring protection to encephalitis when vaccinated cattle were challenged with a large infectious dose of the parental wild type BoHV-5. However, it did not avoid the establishment of latency nor impeded dexamethasone-induced reactivation of the virus, despite a significant reduction in virus shedding after challenge and at reactivation on vaccinated calves.     

Molecular characterization of Cryptosporidium spp. in grazing beef cattle in Japan

Cattle are major hosts of Cryptosporidium spp. Cryptosporidiosis in neonatal calves is associated with retarded growth, weight loss and calf mortality, and zoonotic infections in humans. In many areas, cow-calf glazing system is an important beef cattle rearing method with distinct advantages in terms of cost and the labor required. However, few epidemiologic studies of Cryptosporidium spp. have been conducted in this system, especially using molecular diagnostic tools. To understand the transmission of Cryptosporidium spp. in a grazing system, we followed cryptosporidiosis on a grazing farm in Osaki City, Miyagi Prefecture, in northwest Japan for one year. Fecal samples were collected from Japanese Black and Japanese Shorthorn cattle and examined by PCR-RFLP and sequence analyses. Of 113 fecal samples collected in October 2010, 23 (20%) were positive for Cryptosporidium, including 15 samples (13%) having C. bovis, 6 (5%) having C. ryanae, and 2 (2%) having mixed infections of both species. Additionally, C. bovis or C. ryanae was detected on all other sampling dates involving smaller numbers of animals. The infection rate of C. bovis was significantly different among age groups, and calve-to-calve infection might be the major route of cryptosporidiosis transmission in beef cattle. Interestingly, one animal had C. bovis infection or re-infection for one year. Our results suggest that C. bovis and C. ryanae are distributed in Japan, but might have low level of detection in grazing beef cattle.     

Bovine leukemia virus infection in Taiwan: epidemiological study.

We conducted a seroepidemiological survey for antibodies to bovine leukemia virus (BLV), by using agar gel immunodiffusion technique, in dairy cows, water buffaloes, and yellow cattle throughout Taiwan. The positive reactors were 8.4% (376/4,459) in 1985 and 5.8% (1,277/22,190) in 1986, in 15 prefectures and 7 cities. Relatively high infection rate appeared in the northern and southern areas of Taiwan. Positive reactors increased gradually with age. The incidence of positive antibodies was 2 to 3 times higher in pasture-style farms than in housed-style farms. Among the 6,313 imported cattle, 302 (4.8%) showed positive reaction. Between 1985 and 1987, 5 cattle showed enzootic bovine leukosis among 351 sero-positive reactors in four highly positive prefectures. Survey of 134 water buffaloes and yellow cattle showed no positive reactors. This survey demonstrated that BLV-infection has increased over the years and spread throughout Taiwan.     

Comparison of a competitive inhibition ELISA and the card agglutination test for detection of antibodies to Anaplasma marginale and Anaplasma centrale in cattle

OBJECTIVE: To compare a recently developed recombinant MSP-5 competitive inhibition ELISA with a card agglutination test for detection of antibodies to Anaplasma marginale and Anaplasma centrale in Australian cattle. MATERIALS AND METHODS: The ELISA was compared with the card agglutination test using 208 sera from cattle in Anaplasma-free herds, 86 sera from cattle experimentally infected with A marginale or A centrale and 757 sera from cattle in areas endemic for A marginale. RESULTS: The specificity of the ELISA, based on testing 208 sera from cattle in Anaplasma-free areas, was 99.5%, and the sensitivities for detection of antibodies to A marginale and A centrale in sera from the experimentally infected cattle were 98.0% and 100%, respectively. For the same sets of sera, the specificity of the card agglutination test was 98.6% and the sensitivities for detection of antibodies to A marginale and A centrale were 98.0% and 100%, respectively. For the 757 sera collected from cattle in areas endemic for A marginale, the agreement between the ELISA and the card agglutination test depended on the positive threshold selected for the ELISA. The maximum achievable agreement was 91.5% (kappa = 0.73; 95% confidence interval 0.66, 0.79). CONCLUSION: We conclude that the competitive inhibition ELISA is a useful alternative to the card agglutination test for detection of A marginale or A centrale infection in cattle. The assay should be particularly useful for epidemiological applications such as prevalence studies and control programs.     

Establishment and evaluation of an iELISA using the recombinant membrane protein LHD-Sj23 for the serodiagnosis of Schistosoma japonicum infection in cattle in China

Schistosomiasis is an important zoonosis and some livestock especially cattle play a crucial role in disease transmission in endemic areas. In order to establish an effective diagnostic method for detecting Schistosoma japonicum infection in cattle, the gene encoding large hydrophilic domain of Sj23 (LHD-Sj23) was cloned and expressed in Escherichia coli as a fusion protein with GST tag. The purified rLHD-Sj23-GST was used as an antigen in an indirect enzyme-linked immunosorbent assay (iELISA). The sera samples collected from cattle experimentally infected with S. japonicum from week 0 to week 54 post-infection were examined by rLHD-Sj23-GST iELISA. Furthermore, 484 clinical sera samples collected from cattle in schistosomiasis epidemic and free areas in China were tested by this method with a positive rate of 18.4% and 3.44%, respectively. The findings from this study indicated the established iELISA is a useful method for diagnosing S. japonicum infection in cattle and could be used in serological surveys to map out the prevalence of this disease.     

Antibodies against bovine herpesvirus 4 are highly prevalent in wild African buffaloes throughout eastern and southern Africa

Bovine herpesvirus 4 (BoHV-4) has been isolated from cattle throughout the world. Interestingly, a survey of wild African buffaloes mainly from the Maasai Mara Game Reserve in Kenya revealed that 94% of the animals tested had anti-BoHV-4 antibodies [Rossiter, P.B., Gumm, I.D., Stagg, D.A., Conrad, P.A., Mukolwe, S., Davies, F.G., White, H., 1989. Isolation of bovine herpesvirus-3 from African buffaloes (Syncerus caffer). Res. Vet. Sci. 46, 337–343]. These authors also proposed that the serological antigenic relationship existing between BoHV-4 and alcelaphine herpesvirus 1 (AlHV-1) could confer to BoHV-4 infected buffaloes a protective immune response against lethal AlHV-1 infection. In the present study, we addressed two questions related to Rossiter et al. paper. Firstly, to investigate the role of the African buffalo as a natural host species of BoHV-4, the seroprevalence of anti-BoHV-4 antibodies was analysed in wild African buffaloes throughout eastern and southern Africa. A total of 400 sera was analysed using two complementary immunofluorescent assays. These analyses revealed that independently of their geographical origin, wild African buffaloes exhibit a seroprevalence of anti-BoHV-4 antibodies higher than 68%. This result is by far above the seroprevalence generally observed in cattle. Our data are discussed in the light of our recent phylogenetic study demonstrating that the BoHV-4 Bo17 gene has been acquired from a recent ancestor of the African buffalo. Secondly, we investigated the humoral antigenic relationship existing between BoHV-4 and AlHV-1. Our results demonstrate that among the antigens expressed in AlHV-1 infected cells, epitope(s) recognised by anti-BoHV-4 antibodies are exclusively nuclear, suggesting that the putative property of BoHV-4 to confer an immune protection against AlHV-1 relies on a cellular rather than on a humoral immune response.     

Long-term study (2005–2010) on the vaccination with BoHV-1 glycoprotein E-deleted marker vaccine in selected two dairy herds in Turkey

A follow-up study from 2005 to 2010 was carried out in two herds where eradication programme for the bovine herpes virus-1 (BoHV-1) infection depends on the vaccination with inactivated glycoprotein E-deleted vaccine that was started in 2001 following the vaccination with inactivated conventional vaccine between 1999 and 2001. For serological screening, a total of 12,976 sera sampled over several sampling times approximately 6 months of interval during 5 years (2005–2010) were tested for glycoprotein E (gE)- and glycoprotein B-specific antibodies using ELISA. According to the serological evidence, the long-term persistence of BoHV-1 antibodies, success of marker vaccine, first vaccination time of the calves in herds regularly vaccinated, etc. were discussed in this paper. In conclusion, the vaccination programme using gE (?) marker vaccines, with making efforts to prevent the other factors about transmission of infection, was suggested for the eradication of BoHV-1 infection in Turkey as many EU countries. This is the first report on the BoHV-1 eradication programme in some dairy cattle in Turkey.     

Prevalence of blood parasites among cattle at the central area of Saudi Arabia

The present study aimed to investigate the parasites infecting cattle blood at Al-Qassim region. Examination of 307 blood samples revealed that 235 (76.5%) and 3 (0.98%) of cattle were infected with Theileria annulata and Anaplasma marginale, respectively. T. annulata was the prevalent blood parasite among cattle while A. marginale was scarcely encountered. The monthly incidence of T. annulata ranged from 38.5% in March to 94.7% in October. Also, the infection rate reached a maximum (84.3%) in both autumn and summer seasons, while it decreased to reach (59.4%) in spring. It has been found that there was no difference between the infection rate of the laboratory and the abattoir collected samples. However, the intensity of infection was different between the two groups.     

Epidemiological survey of Border disease virus among sheep from northern districts of Japan

The first epidemiological survey of Border disease virus (BDV) was undertaken in small ruminants in Japan. Ovine sera, collected from the northern prefectures of Hokkaido, Aomori and Iwate, were examined for the presence of antibodies against BDV using the neutralization peroxidase-linked antibody test. Twenty-nine (17.6%) of one hundred and sixty-five samples were seropositive for BDV. Results were specific, excluding cross-reactions with bovine viral diarrhea virus (BVDV). Only one sample (0.6%) was positive for BVDV, and was negative for BDV. Despite serological evidence of virus circulation, there have been no clinical cases of border disease in sheep in Japan. Although no diagnostic measures were performed, the infection did not appear to be associated with a reduction in ewe fertility nor with lamb mortality.     

Prevalence and distribution of bovine coccidia in Japan

A field survey was carried out on prevalence of bovine coccidia in 9 prefectures of Japan in the autumn of 1985. A total of 1,015 fecal samples was obtained from dairy and beef cattle more than 2 weeks old. Coccidial oocysts were found in 59.0% of all the samples examined. There were no significant differences in the prevalence between dairy and beef cattle of the same age group. The prevalence was the highest in the animals between 6 and 11 months old and decreased to 25% in those more than 24 months old. In the majority of the samples positive for oocysts, OPG (the number of oocysts per gram of feces) was less than 200. No clinical coccidiosis was found except in a few cases. Eleven Eimeria and one Isospora species were identified. Of these species, E. bovis and E. ellipsoidalis were the most prevalent, followed by E. aubrunensis, E. brasiliensis, and E. cylindrica in all the prefectures. The other species identified were E. canadensis, E. alabamensis, E. zuernii, E. wyomingensis, E. bukidnonesis, E. subspherica, and Isospora sp. in the order of frequency. Isospora sp. will be a pseudoparasite caused by the contamination with feces of passerine birds.     

Genetic and pathobiological characterization of bovine viral diarrhea viruses recently isolated from cattle in Japan

The 475 strains of bovine viral diarrhea virus (BVDV) isolated from cattle in 12 prefectures of Japan in the last 7 years were phylogenetically classified as BVDV-1 or BVDV-2 on the basis of the nucleotide sequence of the 5'-untranslated region. BVDV-1 strains were further subtyped as 1a (101 strains), 1b (163), 1c (128), 1j (3), and So CP/75-like (1), and all of the 79 BVDV-2 strains belonged to subtype 2a. These 2a BVDVs contain two isolates that had high nucleotide identities with those of highly pathogenic BVDV-2 strains reported in North America (Pellerin et al., 1994). However, acute infection with severe mortality like North American outbreak was not observed and most of the present BVDV-2 strains were isolated from persistently infected (PI) cattle showing mild or no clinical sign. Moreover, it was revealed that 61.5% of the 39 PI cattle with cytopathogenic BVDVs did not show typical mucosal disease and 54.6% of the 405 PI animals only with non-cytopathogenic BVDVs were apparently healthy. The present results indicate that the prevention of the infection with an appropriate vaccine and active surveillance covering healthy cattle are required for the control of BVD.     

Susceptibility of mice to bovine herpesvirus type 5 infection in the central nervous system

Bovine herpesvirus type 5 (BoHV-5) is an important pathogen that causes meningoencephalitis in cattle. Few studies have used the mouse as a model for BoHV-5 infection. Despite the fact that BoHV-5 can infect mice with immune deficiencies, little is known about viral replication, immune response, and the course of infection in the central nervous system (CNS) of wild-type mice. Therefore, the aim of this study was to evaluate the response in the CNS of BALB/c mice acutely infected with BoHV-5 at different days post-inoculation (dpi). BoHV-5, when inoculated intracranially, was able to infect and replicate within the CNS of BALB/c mice. Until 15 dpi, the mice were able to survive without showing prominent neurological signs. The infection was accompanied by a Th1 immune response, with a significant expression of the cytokines IFN-γ and TNF-α and chemokine CCL-2. The expression of these cytokines and chemokines was most significant in the early course of infection (3 and 4 dpi), and it was followed by meningoencephalitis with perivascular cuffing and periventriculitis, composed mainly of macrophages and lymphocytes. After the expression of cytokines and chemokine, the mice were able to curb BoHV-5 acute infection in the brain, since there was a decrease in the number of BoHV-5 DNA copies after 3 dpi and viable viral particles were not detected after 6 dpi. Importantly, BoHV-5 was able to infect the trigeminal ganglia during acute infection, since a large number of BoHV-5 DNA copies were detected on 1 and 2 dpi.