Influence sexual dimorphism on the persistence of blood parasites in infected Calomys callosus

Gender has long been known to be a contributory factor in the incidence and progression of disorders associated with immune system disregulation. The aims of this experiment were to verify the influences of sexual dimorphism on the persistence of blood parasites out of the acute phase of infection. Male and female Calomys callosus were separated and infected with two strains of Trypanosoma cruzi, and let age until 120 days. Xenogiagnostic, culture of organs and blood, histopathology and lytic antibody percentages were evaluated on late chronic phase. Xenodiagnosis, hemoculture and lytic antibody percentages were positive from 45 until 120 days. For both strains in adrenal and heart, amastigote burdens were present until 45 days, scarcely found on 60 days and absent on 120 days. Steroid hormones, although having a protective role, does not enable animals to get completely rid of the infection. Even without showing apparent signs of pathological unbalance, parasites persists, hidden throughout the host’s body.     

Indirect fluorescent antibody and complement fixation tests in the diagnosis of bovine theileriosis and babesiosis in Japan

Antibodies against Theileria sergenti and Babesia ovata were detected by indirect fluorescent antibody (IFA) and complement fixation (CF) methods. Both of the antibodies against T. sergenti and B. ovata could be detected with a single IFA testing procedure. Complement fixing antibody tests for T. sergenti in experimentally infected cattle were positive for about 70 days after the parasites could no longer be detected in the blood smear, and were negative thereafter. B. ovata CF antibody titres were negative on the 270th day post-infection, while the IFA tests against both parasites were positive for longer periods. B. ovata IFA-test titres remained relatively high until the 420th day after inoculation. In a survey of sera from naturally infected animals, the rate of detecting antibodies against both parasites was higher using the IFA test than using the CF test. The IFA method was more effective for diagnosis of Babesia infection than the CF technique.     

Course of experimental infection of canine leishmaniosis: Follow-up and utility of noninvasive diagnostic techniques

This study compares the utility of a molecular diagnosis of experimental CanL on non-invasive samples (urine, conjunctival (CS), oral (OS) and vulvar (VS) swabs) with that of traditional invasive techniques during the course of infection. Eight dogs were experimentally infected with Leishmania infantum and followed monthly for 12 months to assess clinical, clinicopathological, immunological and parasitological variables. Active infection was produced in 100% of the dogs. The animals showed positive bone marrow (BM) cytologies and cultures, clinical signs, clinicopathological abnormalities and a high specific humoral immune response. The infection was detected at 90 days post-infection (p.i.) by real-time quantitative PCR (rtQ-PCR) on BM in all dogs and in blood in 2 dogs, while anti-L. infantum antibody seroconversion occurred between Days 120 and 180 days p.i. The tissue with the highest L. infantum kDNA load, as detected by rtQ-PCR, was BM (range 381.5–70,000 parasites/ml at the study end), this sample type showing greater sensitivity than peripheral blood (PB). The vulvar swabs used here for the first time to quantify parasite loads in dogs revealed a greater load than oral and conjunctival swabs at one year p.i. Urine samples showed the lowest concentrations of L. infantum DNA (maximum: 8.57 parasites/ml). Our results suggest that for the early detection of infection, adding to serology a test such as rtQ-PCR on OS or VS improves sensitivity and specificity.     

The immune response against Chlamydia suis genital tract infection partially protects against re-infection

The aim of the present study was to reveal the characteristic features of genital Chlamydia suis infection and re-infection in female pigs by studying the immune response, pathological changes, replication of chlamydial bacteria in the genital tract and excretion of viable bacteria. Pigs were intravaginally infected and re-infected with C. suis strain S45, the type strain of this species. We demonstrated that S45 is pathogenic for the female urogenital tract. Chlamydia replication occurred throughout the urogenital tract, causing inflammation and pathology. Furthermore, genital infection elicited both cellular and humoral immune responses. Compared to the primo-infection of pigs with C. suis, re-infection was characterized by less severe macroscopic lesions and less chlamydial elementary bodies and inclusions in the urogenital tract. This indicates the development of a certain level of protection following the initial infection. Protective immunity against re-infection coincided with higher Chlamydia-specific IgG and IgA antibody titers in sera and vaginal secretions, higher proliferative responses of peripheral blood mononuclear cells (PBMC), higher percentages of blood B lymphocytes, monocytes and CD8⁺ T cells and upregulated production of IFN-γ and IL-10 by PBMC.

Electronic supplementary material

The online version of this article (doi:10.1186/s13567-014-0095-6) contains supplementary material, which is available to authorized users.     

Pathology of female mice experimentally infected with an in vitro cultured strain of Trypanosoma equiperdum

Dourine, caused by infection with Trypanosoma equiperdum, is one of the trypanosomiasis in equids. The clinical course of dourine is long-term, ranging from 1–2 months to several years. Since the pathogenesis of dourine has not yet been elucidated, experimental studies using mouse infection models are needed. Although mice are not susceptible to most T. equiperdum strains, some strains can infect mice. Even in such strains, infected mice develop rapidly transient parasitemia and die within 2–8 days. Therefore, mice experimentally infected with these T. equiperdum strains are not suitable for mouse infection models to analysis the pathogenesis of dourine. A sequential method of isolating parasites from dourine-affected horses and adapting them to in vitro cultures using soft agarose media was recently developed. Various T. equiperdum strains adapted to in vitro conditions have been established using this technique. We used one of these strains, the T. equiperdum IVM-t2 strain. In the present study, T. equiperdum IVM-t2 strain inoculated mice developed periodic parasitemia during the experimental period of 60 days. Histopathologically, vaginitis and dermatitis were observed. These findings were comparable to those of dourine-affected horses. Therefore, mice infected with T. equiperdum IVM-t2 strain may be a valuable tool for pathological, immunological, and parasitological in vivo research, and will contribute to investigations on the mechanisms underlying the disease process and the host-parasite relationship.     

Use of monoclonal antibodies for detecting T brucei brucei infection in splenectomised dogs

A monoclonal antibody against a plasma membrane antigen of Trypanosoma rhodesiense was used for the detection of T brucei group-specific circulating antigen in 24 adult local dogs experimentally infected with T brucei brucei strain 8/18. Ten of the dogs were splenectomised and the remainder non-splenectomised (intact). Five dogs each from the splenectomised and intact groups were inoculated intravenously with try-panosomes. The infected dogs developed trypanosomiasis between days 4 and 8 after infection. The circulating antigens were detected as early as six days after infection and remained high until two weeks after treatment, when the circulating antigen declined. The detection of the antigens showed the existence of infection unlike the antibody test. The treatment of the infected dogs with diminazene aceturate (Berenil; Hoechst) at a dose of 7-0 mg/kg on day 21 after infection cleared all the parasites but elevated the circulating antigen levels. The antigen capture enzyme-linked immunosorbent assay is a useful diagnostic tool for complementing parasitological diagnosis, for detecting infection in the field and for ascertaining the efficacy of trypanocidal drugs.     

Effect of age on the immune response of cattle experimentally infected with Babesia bigemina

Two different age groups of Holstein Friesian cattle were experimentally infected with Babesiabigemina. Calves of group A (6 months old) did not show noticeable symptoms of babesiosis and had relatively low (0.6%) numbers of parasites in their red blood cells (RBCs). Group B calves (1 year old) had typical signs of the disease; parasites were found in 6.6% of their RBCs. Blood from both groups inoculated into splenectomized calves at 3, 6, 12 and 18 months following initial inoculation demonstrated the presence of B. bigemina, while after 22 months no parasites could be demonstrated.The indirect fluorescent antibody (IFA) test detected babesial antibodies at 4–5 days post inoculation (PI) and reached a maximum titre of 1 : 640 at 2 weeks PI. Following challenge at 2–3 months after initial inoculation, the antibody titre rose sharply to 1 : 2560, then decreased gradually but was still detectable 22 months PI. No correlation was found between antibody titre and the presence of the parasite hin the peripheral blood.     

Babesia ovis infections: Detailed clinical and laboratory observations in the pre- and post-treatment periods of 97 field cases

Ovine babesiosis, caused by Babesia ovis, is of major economic importance in Turkey. The changes in the blood profile of infected animals are informative about the course of infection. The aim of the present study was to evaluate the hematological and biochemical changes in the pre- and post-treatment periods of the natural B. ovis infections. The presence of the parasites was confirmed by microscopy and polymerase chain reaction (PCR) analysis. On the basis of the clinical and laboratory findings, the infections were categorized into different groups according to the degree of anemia and the level of parasitemia. All infected sheep were treated with imidocarb dipropionate (IMDP). The blood pictures in the pre- and post-treatment periods were compared.Pancytopenia occurred in animals with severe anemia and very high parasitemia, and bicytopenia in the other groups. The platelet count (PLT), plateletcrit (PCT) and mean platelet volume (MPV) returned to the normal ranges after treatment, except those in the group with severe anemia. In the biochemical profile, B. ovis infection caused an increase in blood urea nitrogen and total bilirubin, and these parameters returned to normal levels after treatment.The indirect fluorescein antibody test (IFAT) results showed that 38.1% of the cases raised specific antibodies during the period of infection, with titers ranging from 1/160 to 1/640. All of 45 animals re-examined after treatment were seropositive, with high titers that rose up to 1/5120.     

Serological responses to bovine anaplasmosis following treatment with gloxazone

Groups of unsplenectomised steers and calves were infected with either the Onderstepoort or Sukari 1 strain of Anaplasma marginale by the injection of infected blood. The infections were treated with gloxazone (2.5 – 25 mg/kg). The serological response of the animals was monitored by the complement fixation (CF) and capillary tube agglutination (CA) tests, using antigens prepared from the Onderstepoort strain. CF antibody responses were alike in both strains. The titre rose rapidly from four days after infection to a peak around the time of the initial crisis. These high titres were maintained, and generally did not rise further at the time of recrudescence of parasitaemia. CA antibody appeared 7–10 days after infection and reached a peak shortly after the initial crisis. Titres fell as parasitaemia was reduced following gloxazone treatment, then rose as parasitaemia recrudesced. There was a close correlation between the effectiveness of gloxazone treatment and changes in CA antibody titre.     

Duration of naturally acquired giardiosis and cryptosporidiosis in dairy calves and their association with diarrhea

OBJECTIVE: To determine duration of infection and association of infection with diarrhea for dairy calves with naturally acquired cryptosporidiosis and giardiosis. DESIGN: Cohort study. ANIMALS: 20 Holstein calves on a single dairy farm. PROCEDURE: Fecal samples were collected 3 times/wk for the first 45 days after birth, then weekly until calves were 120 days old and examined for Giardia duodenalis cysts and Cryptosporidium parvum oocysts. Calves were monitored for diarrhea during the first 45 days after birth; during each episode of diarrhea, fecal samples were examined for parasitic, bacterial, and viral pathogens. RESULTS: All 20 calves shed Giardia cysts and Cryptosporidium oocysts at some time during the study. Mean ages at which Giardia cysts and Cryptosporidium oocysts were first detected were 31.5 and 16.3 days, respectively. Mean number of Giardia cysts in feces remained high throughout the study, whereas Cryptosporidium occysts decreased to low or undetectable numbers 2 weeks after infection. Eighteen calves had a total of 38 episodes of diarrhea during the first 45 days after birth. Giardia duodenalis was the only pathogen identified during 6 (16%) episodes, C parvum was the only pathogen identified during 9 (24%) episodes, and G duodenalis and C parvum were identified together during 10 (26%) episodes. CONCLUSIONS: Prevalences of giardiosis and cryptosporidiosis were high in these calves, and both parasites were associated with development of diarrhea. Cryptosporidium parvum was an important pathogen when calves were < 1 month old, but G duodenalis was more important when calves were older. Calves cleared C parvum infections within 2 weeks; however, G duodenalis infections became chronic in these calves.     

Development of villus atrophy in the small intestine of sheep infected with Trichostrongylus rugatus

Pairs of sheep infected with 120 000 larvae of Trichostrongylus rugatus were killed at intervals from 2 to 56 days after infection (DAI). Worms were located in tunnels in the epithelium of villi or upper intestinal crypts at all stages of development. Villus atrophy developed progressively until 16 DAI, when surface microtopography, characterised by subtotal villus atrophy, stabilised. Most severe lesions were in the first 3 m of small intestine where the density of nematodes was highest. Discontinuities in the epithelium and effusion of inflammatory cells and tissue fluids into the lumen were rare. No effects of infection on body-weight gain, appetite or serum total protein and albumin were evident in the first 20 days of infection. However, it was concluded that T. rugatus fundamentally resembled T. colubriformis and T. vitrinus in the response it elicited in the intestine of sheep, and must be considered potentially pathogenic.     

Polyclonal activation of B cells occurs in lymphoid organs from porcine reproductive and respiratory syndrome virus (PRRSV)-infected pigs

Porcine reproductive and respiratory syndrome virus (PRRSV) induces a persistent viral infection associated with an inefficient humoral immune response. A study of lymphoid B cells and specific humoral immune response was performed in blood and several lymphoid organs collected from PRRSV experimentally-infected pigs. Groups of specific pathogen-free (SPF) pigs were infected with the LHVA-93-3 isolate of PRRSV, and blood, tonsils, spleen and mediastinal lymph nodes (MLN) were collected at various times postinfection (p.i.) (3-60 days). Lymphoid cells were isolated, immunolabeled for cytofluorometric determination of B cell percentages, used for counting specific anti-PRRSV antibody secreting B cells by an ELISPOT assay, or cultured for metabolic activity. The presence of anti-PRRSV antibodies in the serum of infected pigs was determined using a commercial ELISA assay. Virus detection was performed in all tissues, including lungs, by virus isolation and RT-PCR. The results show that percentages of B cells increased in tonsils as soon as 3 days until 17 days p.i. in PRRSV-infected pigs while they increased in spleen at 3 days p.i. only, due to an increase of larger Ig(high)-producing B cells. Metabolic activity of lymphoid cells from blood and spleen increased at 3 days p.i. only while lymphoid cells from tonsils and MLN transiently decreased at that time and increased thereafter up to 60 days p.i. Anti-PRRSV antibody-secreting B cells occurred in tonsils after 10 days p.i. and strongly increased up to 60 days p.i. However, specific anti-PRRSV-secreting B cells were detected in blood and spleen after 17 days p.i and in MLN only after 45 days p.i. Specific antibodies were detectable in serum at 10 days p.i., reached the maximum level at 45 days and remained high up to 60 days p.i. Infectious virus was detected in lungs and MLN as soon as 3 days p.i., and remained detectable up to 45 days p.i. in tonsils of one pig while viral RNA was detected in most organs up to 60 days p.i. In vitro experiments revealed that inactivated virus induced a stimulation of lymphoid cells isolated from PRRSV-infected pigs while it was cytotoxic for lymphoid cells from control pigs. Taken together, these results indicate that viral infection induced simultaneously a polyclonal activation of B cells, mainly in tonsils, and an exaggerated and prolonged specific humoral immune response due to persistent viral infection in lymphoid organs.     

Efficacy of ‘indigenous vaccine’ using native ‘Indian bison type’ genotype of Mycobacterium avium subspecies paratuberculosis for the control of clinical Johne’s disease in an organized goat herd

Therapeutic efficacy of a new ‘Indigenous vaccine’ prepared from native highly pathogenic ‘Indian Bison Type’ genotype of Mycobacterium avium subspecies paratuberculosis (MAP) of goat origin has been evaluated with respect to control of clinical Johne’s disease in naturally infected Mehsana breed of goat in North Gujarat. Fifty goats from Sheep and Goats Research Station, Sardarkrushinagar Dantiwada Agricultural University, Sardarkrushinagar, were randomly divided into 2 groups viz.,‘Vaccinated’(n?=?35) and ‘Control’(n?=?15). After vaccination, goats were monitored for physical condition, morbidity, mortality, body weights, shedding of MAP in feces, internal condition, gross lesions and humoral immune responses up to 120 days (at each interval of 30 days). At the end of 120 days trial, there was marked overall improvement in physical condition and body weights of vaccinated goats as compared to ‘Control’ goats. Vaccinated goats gained significantly (P?<?0.05) higher body weights, hardly exhibited any lesions characteristic of JD, had significantly higher (P?<?0.01) antibody titers and shedding of MAP was significantly (P?<?0.01) reduced. Few of the vaccinated goats were positive for MAP DNA in faecal PCR and blood PCR before vaccination. However, all were found as negative at 120 days post vaccination (DPV). Overall vaccine exhibited effective in restriction of MAP infection and significant improvement in production parameters and reduction in mortality and morbidity due to JD. The trial in the herd will be continued.     

Concurrent vaccination of goats with foot and mouth disease (FMD) and peste des petits ruminants (PPR) booster vaccines

Foot and mouth disease (FMD) remains subclinical and self-limiting in small ruminants, but risk of spread of infection to susceptible cohorts is of great epidemiological significance; therefore, small ruminants must be included in vaccination campaigns in FMD endemic regions. Three groups of goats already immunized against peste des petits ruminants (PPR) were vaccinated with FMD and PPR vaccines alone or concurrently. The specific antibody response against three FMD virus strains and PPR virus were evaluated by competitive enzyme-linked immunosorbent assay (cELISA). Goats concurrently vaccinated with PPR + FMD vaccines had significantly (p < 0.05) higher antibody titers to two serotypes of FMD virus at 28, 45, and 60 days post-immunization compared to goats vaccinated with FMD vaccine alone, while goats vaccinated with PPR vaccines alone or PPR + FMD vaccines concurrently showed similar antibody kinetics against PPR virus up till 60 days post-vaccination. Overall, antibody kinetic curves for all three tested strains of FMD virus and PPR virus were similar in vaccinated groups during the course of experiment.     

An enzyme-linked immunosorbent assay (ELISA) for detection of antibodies against Toxocara vitulorum in water buffaloes

Toxocara vitulorum, a parasite of the small intestine of cattle and water buffaloes, is mainly acquired by calves via the colostrum/milk from infected cows. To understand the development of immune responses in calves, antibody levels to a soluble extract antigen (Ex) from T. vitulorum infective larvae were measured by an indirect ELISA with sera of 15 buffalo calves, which were sampled every 15 days for the first 180 days after birth and 9 buffalo cows during the perinatal period. From all serum samples examined during the first 180 days, antibody level was lowest and highest in calves at 1 day of age before and after suckling colostrum, respectively, suggesting that the origin of antibodies was the colostrum. Immediately after birth, antibody levels in suckled calves remained at high levels until day 15, began to decrease to lower levels between 15 and 30 days and remained relatively stable until 120 days. By comparing the immune responses of these animals with their parasitological status it was considered possible to determine if passively acquired or actively produced antibodies provided protection against the infection. High numbers of T. vitulorum eggs in the feces between 30 and 60 days indicated that passively acquired antibodies did not provide protection against the infection, at least during these first days, and the maximum fecal egg counts during 30-45 days were coincident with decreased antibody levels. Between 60 and 120 days, when serum antibodies were detected at reduced, but stable levels, adult nematodes were expelled from the intestines and no more T. vitulorum eggs were found, suggesting development of acquired resistance. However, the potential and functional protective role of the antibodies against T. vitulorum infection and the process of self-cure requires further investigation.     

Experimental Leptospira interrogans Serovar Kennewicki Infection of Horses

Background: Little information is available about experimental induction of leptospirosis in horses. Objectives: Determine serologic, hematologic responses of horses to Leptospira interrogans serovar Kennewicki infection. Animals: Four adult horses seronegative for leptospirosis. Methods: Experimental and observational study. Horses were challenged with an equine isolate of L. interrogans serovar Kennewicki at 2 different doses and different inoculation sites. After challenge, the horses were monitored for 60 days. Blood, urine, and aqueous humor samples were collected at intervals until euthanasia 60 days after infection. Results: Pyrexia (39.3–40°C) occurred as early as 1 day after challenge with 10 × 10⁸Leptospira divided equally between topical ocular and intraperitoneal injection in 2 horses. Leptospires were recovered from the blood and urine but not from the aqueous humor of the 2 febrile horses. The sera of all 4 challenged horses developed microscopic agglutination test antibody after challenge and remained relatively constant for 21 days. Titer to cross‐reacting strains declined earlier than titer to the challenge strain. Conclusions: Clinical disease in experimentally infected horses can be mild or inapparent in Leptospira infected horses. Repeated serologic testing can allow recognition of the infecting serovar. In febrile horses, Leptospira can be isolated from blood while isolation from the urine can occur after fever has subsided.     

Studies on the blood parasites of pigs in Ibadan,Nigeria

The blood parasites in the blood of local pigs kept under free range, and exotic pigs kept under intensive management in Ibadan were investigated. The species found were Babesia trautmanni, B. perroncitoi, Eperythrozoon suis and E. parvum. Eperythrozoon suis was the most predominant in both breeds. Most of the local pigs carried mixed infections, while the same number of the exotic pigs carried single and mixed infections. Mixed infection of individual pigs with all four blood parasites was common. The parasitaemia was generally low in pigs of both breeds.     

Embryo Transfer in Anovulatory Recipient Mares Treated with Estradiol Benzoate and Long-Acting Progesterone

This study aimed to prepare anovulatory mares in anestrus or in the transitional period as embryo recipients. Ninety embryo-recipient mares were divided into two groups (G). G1 (n = 45) comprised animals in anestrus or in the transitional period; these animals were treated for 3 days (D) with 5, 3, and 2 mg of estradiol benzoate (intramuscular) on D0 (day of the donor's ovulation), D1, and D2 (after ovulation), respectively, followed by weekly application of 400 mg of long-acting progesterone (intramuscular) from D3 after ovulation (donor) until the 120th day of gestation. G2 (n = 45) comprised mares with normal estrous cycles. Plasma levels of progesterone (P₄) were measured on days D1, D2, D8, and D14. Sixty percent of the animals in G1 and 71.1% in G2 (P > .05) completed the pregnancy. On D8, there was no difference in P₄ levels between G1 and G2 animals, but there was a difference in P₄ levels on D14 (P < .05). It was concluded that anovulatory mares in anestrus or in the transitional period could be used as embryo recipients. The protocol was efficient and also considered an appropriate alternative to prepare the uterine environment for embryo transfer; long-acting progesterone administration kept P₄ levels high enough to maintain pregnancy until the 120th day and provided recipients during the time of the year when fewer mares were cycling and ovulating.     

Assessing the duration of persistence and shedding of porcine reproductive and respiratory syndrome virus in a large population of breeding-age gilts

Porcine reproductive and respiratory syndrome virus (PRRSV) is an RNA virus in the order Nidovirales, family Arteriviridae, genus Arterivirus. The virus induces a prolonged viremia, replicates in macrophages, and produces persistent infection. The purpose of this study was to determine if PRRSV could persist for 90 d or more in a large population of breeding-age gilts housed under environmental conditions typical of commercial swine production and to determine if experimentally infected gilts could shed virus to naïve sentinel gilts beyond 90 d postinfection. Using the intranasal route, we inoculated 120 PRRSV-naïve gilts, 4 mo of age, with 5 mL of cell culture fluid containing a total dose of 10^2.4 TCID₅₀ of a field isolate (MN-30100) of PRRSV. The index gilts were organized into 3 groups (A, B, and C), 40 gilts per group. To assess the dynamics of the experimental infection, a monitor group of 30 index gilts was blood-tested on days 0, 3, 7, 14, 30, 60, 90, 120, 150, and 180 postinfection. PRRSV viremia was detected with the polymerase chain reaction (PCR) on days 3, 7, and 14 and by virus isolation (VI) on days 7 and 14. PRRSV antibodies were detected from day 14 by enzyme-linked immunosorbent assay (ELISA). To assess shedding, 30 PRRSV-naïve sentinel gilts were commingled with the index gilts on day 90 postinfection and tested by PCR, VI, and ELISA every 15 d until 180 d postinfection; all samples were negative. To assess persistence, 40 index and 10 sentinel gilts were slaughtered at 120 (group A), 150 (group B), or 180 (group C) d postinfection. Evidence of PRRSV was not detected by PCR or VI in any tissue samples from the 120 index gilts. These results indicate that persistence and shedding of PRRSV are of short duration in breeding-age gilts.