Mammary Infection Research Articles

Evidence That Mammary Gland Infection/Injury During Pregnancy in Dairy Cows May Have a Negative Impact on Size of the Ovarian Reserve in Their Daughters.

The effect of disease on maternal environment, which has a crucial role in embryo development and subsequent health of offspring, has not been examined extensively in cattle. Therefore, the purpose of this study was to determine if a persistent mammary gland infection such as mastitis and correspondingly a chronically high (> 200,000 units) somatic cell count (SCC) in milk of pregnant dairy cows has a potential negative impact on size of the ovarian reserve (total number of healthy follicles and oocytes in ovaries) and potentially fertility of their offspring. This study was conducted at Green Meadow Farms Inc. in Elsie, MI and used 192, 12-mo-old Holstein heifers. Each animal was injected with 2 injections of prostaglandin F2 alpha (PG) spaced 11 d apart. To assess relative size of the ovarian reserve in each heifer, a single blood sample was removed 4 d after the 2nd PG injection and assayed for concentration of anti-Müllerian hormone (AMH), and ovarian ultrasonography was used to determine number of follicles ≥ 3 mm in diameter and ovary size. Results confirm previous observations that AMH concentrations were highly variable among animals but positively correlated (P < 0.001) with both ovary size and number of antral follicles. To determine if a chronic mammary gland infection during pregnancy of dairy cows was associated with alterations in AMH concentrations and correspondingly size of the ovarian reserve in their offspring, we next tested whether number of SCC measurements > 200,000 for each heifer's dam was associated with alterations in the serum AMH concentration in each heifer. Number of SCC measurements > 200,000 per individual cow is an accurate index of recurrent udder infections, injury and/or inflammation. A total of 5 to 7 measurements of SCC were made for each dairy cow beginning 2 mo before pregnancy and continuing throughout pregnancy. Number of SCC measurements > 200,000 ranged from 0 to 5 per individual cows, thus cows were separated into groups based on their number of SCC measurements > 200,000. Cows with 4 or 5 SCC measurements > 200,000 were ~2 years older (P < 0.01, 6.1 vs 4.4 yrs old) and tended (P < 0.09) to produce less milk compared with cows that had 0 to 3 SCC measurements > 200,000. Results showed that the daughters of cows with 4 and 5 SCC measurements > 200,000 also had markedly lower (P < 0.02) AMH concentrations as young adults compared with daughters of the cows with 0 to 3 SCC measurements > 200,000. Although mechanisms are unclear, our results imply that a chronic mammary infection or injury during pregnancy of older cows (as predicted by a high number of SCC measurements > 200,000) is associated not only with low milk production, but also with diminished size of the ovarian reserve and perhaps reduced reproductive performance (fertility and reproductive lifespan) of their daughters. Research supported by USDA-NRI 2004-01697, 2007-01289 to JJI. (poster)

Short communication: Fluoroquinolone susceptibility of Staphylococcus aureus strains isolated from caprine clinical mastitis in southeast Spain

The antibiotic susceptibility of 32 strains of Staphylococcus aureus isolated from the mastitic milk of dairy goats was evaluated. The antibiotics tested were 3 fluoroquinolones that have been developed especially for use in veterinary medicine: danofloxacin, marbofloxacin, and orbifloxacin. Minimum inhibitory concentration (MIC) tests were performed according to the microdilution broth method. The MIC90 (concentration at which 90% inhibition is achieved) values obtained were 0.5, 1, and 1mg/L for danofloxacin, marbofloxacin, and orbifloxacin, respectively. Danofloxacin was the most active fluoroquinolone tested against Staph. aureus strains isolated from milk; however, specific testing is required before using these drugs as therapy for the control of clinical mammary infections in goats.

Increases in IgA+ B cells in Peyer's patches during milk-borne mouse mammary tumor virus infection are influenced by Toll-like receptor 4 and are completely dependent on the superantigen response

Mouse mammary tumor virus (MMTV) is a milk-borne betaretrovirus that has developed strategies to exploit and subvert the host immune system. Although mammary glands are the final target of infection, Peyer's patches (PP) are the entry site of the virus. Herein, we show that the infection induces increases in the number of PP IgA(+) B cells and higher expression of the α circular transcript, which is a specific marker of the switch to IgA. In addition, IgA(+) B-cell increases correlated with higher levels of cytokines related to IgA class switching, such as interleukin (IL)-5 and IL-6. Of interest, the increases in IgA(+) B cells were lower in Toll-like receptor 4-deficient mice and were completely dependent on the presence of superantigen-reactive T cells. Our results point to a novel mechanism involved in MMTV infection and suggest that IgA(+) B cells may play an important role in carrying the virus to the mammary glands.

The effect of dry cow therapy and internal teat-sealant on intra -mammary infections during subsequent lactation

Dry cow therapy (DCT), an infusion of antibiotics into the mammary gland at the end of lactation, is widely used for the control of intra-mammary infections (IMI) in the dairy cow. However, increased public health concerns about the use of antibiotics, has led to the search for alternatives to the routine use of antibiotics during drying off. In the present study the effects of three dry cow treatments, two types of DCT and a teat-sealant, on the development of new IMI and clinical mastitis were investigated in 240 cows belonging to two herds (Herd A and Herd B). In Herd A, 60 cows were given one type of DCT (Cloxacillin) and the other 60 cows were given another type of DCT (Framycetin). In Herd B, 60 cows were given teat-sealant and the other herd were not given any treatment. There were significantly more new IMI at calving in control cattle compared to those given teat-sealants ( p < 0.001) and there were more cases of clinical cases of mastitis in the control group. The number of clinical cases detected in cows given teat-sealant in Herd B were not significantly different from those detected in cows in Herd A given Cloxacillin or Framycetin.

Significance of hyperprolactinemia for cytomorphologic features of breast secretions

Nipple discharge syndrome is a clinical entity capable of presenting various disorders such is mammary infection (nonpuerperal and puerperal mastitis), intraductal papillomas, fibrodenoma, breast cancer and hyperprolactinemia syndrome. The aim of the study was to determine differences in cytological features of mammary secretion in patients with hyperprolactinemia and those with normal serum prolactin levels and to define the role of growth hormone, follicle-stimulating hormone, luteinizing hormone and thyroid-stimulating hormone in creating cellular profile of breast secretion. The study included 50 patients with nipple discharge syndrome. The patients were devided into the clinical group (27 patients with hyperprolactinemia and nipple discharge) and the control group I (23 patients with normal serum prolactin and nipple discharge). The control group II included the patients of the clinical group achieving normalised serum prolactin levels after the treatment of hyperprolactinemia. Serum prolactin, follicle-stimulating hormone and luteinizing hormone levels were assessed by RIA using commercial kits IRMA hPRL, hLH and hFSH, (INEP, Zemun, Serbia) while serum growth hormone and thyroid-stimulating hormone levels were assessed by RIA using commercial kits LKB-wallac. Cytologic evaluation of samples, taken from all the patients with mammary secretion, was done using standard techniques of staining Haemathoxilin-eozine and May-Grünwald/Giemsa. Our results showed a significantly higher presence of lipid and protein material in clinical group, in comparison with the control group I (p < 0.01). Also, our data demonstrated significantly higher number of ductal epithelial cells (p < 0.05) and ductal histiocities (p < 0.001) in the clinical group, compared with the control group I. Macrophagies frequency was proportionally higher in clinical group (44.44%) compared the control group I (17.39%). Erythrocites were significantly lower in the clinical group (p < 0.001) than in the control group I. Significantly decreased mammary secretion (p < 0.01), lower lipid (p < 0.01) and protein synthesis (p < 0.01), and less presence of all cellular categories (p < 0.01) were obtained after normalization of serum prolactin levels. Growth hormone, follicle-stimulating hormone, luteinizing hormone and thyroid-stimulating hormone did not show significant influence on creating cytological features of mammary secretion. The most expressive role, hyperprolactinemia demonstrated in the domain of mammary ductal secretory activity, making mammary secretion reach in lipid and protein material and simultaneously increasing number of ductal epithelial cells, ductal histiocytes and "foam cells"--macrophages. These cytological findings indicate that hyperprolactinemia promote periductal and intraductal steril inflammation which withdraws after serum prolactin normalization.

Intramammary challenge of lipopolysaccharide stimulates secretion of lingual antimicrobial peptide into milk of dairy cows

Lingual antimicrobial peptide (LAP) belongs to the β-defensin family in cattle and is found in bovine milk. However, it is unclear whether LAP is involved in the early immune response to mammary infection. The aim of the study was to investigate the changes of LAP concentration in milk after intramammary challenge with lipopolysaccharide (LPS), the gram-negative bacteria cell membrane component, in dairy cows. Milk was collected before and after LPS or phosphate-buffered saline (control) challenge every hour for 12h on d 0 and twice daily from d 1 to 7. Somatic cell count (SCC), LAP concentration, and lactoperoxidase (LPO) activity in the milk were measured. Somatic cell count started to increase at 2h postchallenge and remained high until d 5 (694±187×103 to >1,000±0×103 cells/mL at d 0; >1,000±0×103 cells/mL at d 1 to 3; 684±194×103 to 829±108×103 cells/mL at d 4; 527±197×103 to 656±145×103 cells/mL at d 5). Somatic cell count increased in the control cows, although the levels were lower compared with those in the LPS challenge group. The LAP concentration in milk increased significantly at 2h post-LPS-challenge and was maintained at high levels until d 2 (8.6±0.6 to 17.5±2.3 nM). In the control cow infused with phosphate-buffered saline, there was no increase of LAP concentration in milk (5.1±0.6 to 7.2±0.8 nM). Increase of LPO activity in the milk was observed at 6h after LPS challenge and continued until d 3 (4.7±0.3 to 9.4±1.1 U). No increase of LPO activity was observed in the milk of control cows. The increase and subsequent decrease in LAP concentration after LPS challenge occurred earlier than those of LPO activity. In multiparous cows with LPS infusion, there was a significantly negative relationship between the days leading to the basal levels in LAP concentration and LPO activity (r=−0.75). These results suggest that LPS induces secretion of LAP into milk within hours and that LPO may have a synergistic antimicrobial function with LAP in mammary glands of dairy cows.

Activation of nuclear factor kappa B in mammary epithelium promotes milk loss during mammary development and infection

We investigated whether nuclear factor kappa B (NF-kappaB), which exhibits a regulated pattern of activity during murine mammary gland development, plays an important role during lactation and involution, when milk production ceases and the gland undergoes apoptosis and re-modeling. We generated a doxycycline inducible transgenic mouse model to activate NF-kappaB specifically in the mammary epithelium through expression of a constitutively active form of IKK2, the upstream kinase in the classical NF-kappaB signaling cascade. We found that activation of NF-kappaB during involution resulted in a more rapid reduction in milk levels and increased cleavage of caspase-3, an indicator of apoptosis. We also found that activation of NF-kappaB during lactation with no additional involution signals had a similar effect. The observation that NF-kappaB is a key regulator of milk production led us to investigate the role of NF-kappaB during mastitis, an infection of the mammary gland in which milk loss is observed. Mammary gland injection of E. coli LPS resulted in activation of NF-kappaB and milk loss during lactation. This milk loss was decreased by selective inhibition of NF-kappaB in mammary epithelium. Together, our data reveal that activation of NF-kappaB leads to milk clearance in the lactating mammary gland. Therefore, targeting of NF-kappaB signaling may prove therapeutic during mastitis in humans and could be beneficial for the dairy industry, where such infections have a major economic impact.

Immune Responses and Protection against Experimental Challenge after Vaccination of Bison withBrucella abortusStrain RB51 or RB51 Overexpressing Superoxide Dismutase and Glycosyltransferase Genes

Vaccination is a tool that could be beneficial in managing the high prevalence of brucellosis in free-ranging bison in Yellowstone National Park. In this study, we characterized immunologic responses and protection against experimental challenge after vaccination of bison with Brucella abortus strain RB51 (RB51) or a recombinant RB51 strain overexpressing superoxide dismutase (sodC) and glycosyltransferase (wboA) genes (RB51+sodC,wboA). Bison were vaccinated with saline only or with 4.6 x 10(10) CFU of RB51 or 7.4 x 10(10) CFU of RB51+sodC,wboA (n = eight animals/treatment). Bison vaccinated with RB51 or RB51+sodC,wboA had greater (P < 0.05) antibody responses, proliferative responses, and production of gamma interferon to RB51 after vaccination than did nonvaccinates. However, bison vaccinated with RB51+sodC,wboA cleared the vaccine strain from draining lymph nodes faster than bison vaccinated with the parental RB51 strain. Immunologic responses of bison vaccinated with RB51+sodC,wboA were similar to responses of bison vaccinated with RB51. Pregnant bison were intraconjunctivally challenged in midgestation with 10(7) CFU of B. abortus strain 2308. Bison vaccinated with RB51, but not RB51+sodC,wboA vaccinates, had greater protection from abortion, fetal/uterine, mammary, or maternal infection than nonvaccinates. Our data suggest that the RB51+sodC,wboA strain is less efficacious as a calfhood vaccine for bison than the parental RB51 strain. Our data also suggest that the RB51 vaccine is a currently available management tool that could be utilized to help reduce brucellosis in free-ranging bison.

Expression of Murine APOBEC3 Alleles in Different Mouse Strains and Their Effect on Mouse Mammary Tumor Virus Infection

Recent work has shown that mouse APOBEC3 restricts infection by mouse mammary tumor virus (MMTV) and murine leukemia virus (MLV) and that there are polymorphic APOBEC3 alleles found in different inbred mouse strains. For example, C57BL/6 mice, which are resistant to Friend MLV (F-MLV), encode a APOBEC3 gene different from that encoded by F-MLV-susceptible BALB/c mice; the predominant RNA produced in C57BL/6 mice lacks exon 5 (mA3(-5)) and encodes a protein with 15 polymorphic amino acids. It has also been reported that BALB/c mice produce only a variant RNA that lacks exon 2 (mA3(-2)). In this study, we examined the effect of these polymorphic APOBEC3 proteins on MMTV infection. We found that the major RNA made in C57BL/6 and B10.BR mice lacks exon 5 but that BALB/c and C3H/HeN mice predominantly express an RNA that contains all nine exons. In addition to producing the splice variant, C57BL/6 and B10.BR cells and tissues had levels of mA3 RNA fivefold higher than those from BALB/c and C3H/HeN mice. A cloned C57BL/6-derived mA3 protein lacking exon 5 inhibited MMTV infection better than a cloned full-length protein derived from 129/Ola RNA when packaged into MMTV virions. We also tested dendritic cells derived from different inbred mouse strains for their abilities to be infected by MMTV and showed that susceptibility to infection correlated with the presence of the exon 5-encoding allele. In vivo susceptibility to infection cosegregated with the inherited mA3 allele in a C57BL/6 x BALB/c backcross analysis. Moreover, virus produced in vivo in the mammary tissue of mA3 knockout and BALB/c mice was more infectious than that produced in the tissue of C57BL/6 mice. These data indicate that mA3 plays a role in the genetics of susceptibility and resistance to MMTV infection.

Bovine lactoferrin serves as a molecular bridge for internalization of Streptococcus uberis into bovine mammary epithelial cells

Streptococcus uberis, an environmental mastitis pathogen, is an important causative agent of mastitis in dairy cattle throughout the world. Research from our laboratory demonstrated that bovine lactoferrin (LF), a whey protein present in milk and nonlactating cow mammary secretions, significantly enhanced adherence of S. uberis to mammary epithelial cells in culture. Subsequent research from our laboratory identified S. uberis adhesion molecule (SUAM) showing an affinity for LF. The objective of the present investigation was to test the hypothesis that the interaction between SUAM, bovine LF, and a putative LF receptor on the bovine mammary epithelial cell surface could serve as a bridging molecule for internalization of S. uberis into mammary epithelial cells. When internalization assays were conducted using cell growth medium containing bovine LF, a significant increase in internalization of S. uberis into mammary epithelial cells was observed. However, this effect was reversed when assays were conducted in the presence of antibodies to bovine LF suggesting that internalization of S. uberis into mammary epithelial cells, at least in part, was mediated by LF ligands. When S. uberis was pretreated with antibodies to SUAM, internalization in the presence of LF was reduced in the same manner as observed with antibodies to LF. Transmission and scanning electron microscopy results demonstrated that streptavidin-coated gold particles specifically localized on biotinylated LF receptors on S. uberis and mammary epithelial cell surfaces supporting the availability of LF receptors. Collectively, these results suggest that LF serves as a bridging molecule between SUAM located on the surface of S. uberis and LF receptors located on the surface of mammary epithelial cells thus enhancing internalization of S. uberis into host cells. Exploitation of LF as a molecular bridge for internalization of S. uberis into mammary epithelial cells may confer a significant advantage allowing mammary gland infection.

Short Communication: Early Detection of Mastitis Using Infrared Thermography in Dairy Cows

Infrared thermography (IRT) absorbs infrared radiation and generates images based on the amount of heat generated. It has been used in human medicine for diagnosis of various cancers. This experiment was conducted to determine if IRT had merit for early detection of subclinical mastitis in dairy cows. Milk sample and skin surface temperature (SST) were simultaneously evaluated using the California Mastitis Test (CMT) and IRT for each quarter in 94 dairy cows (49 Brown Swiss and 45 Holstein). Average days in milk (DIM) and milk production were 93±37 d and 16±2.2kg (mean±SD) and their ages ranged from 4 to 8 yr. There was a strong correlation between SST and CMT score (r=0.92). Average SST was 33.19, 34.08, 34.99, and 36.15°C for quarters with the CMT score of 0 (n=156), +1 (n=116), +2 (n=80), and +3 (n=24), respectively. This association was best described by a linear model as follows: y=0.94x + 33.17, R2=0.85, where y=SST and x=CMT score. Changes in rectal temperature (RT) due to the CMT score were minor (y=0.09x + 38.39, R2=0.07, where y=RT and x=average CMT score). In conclusion, RT may not confirm mastitis. However, IRT is sensitive enough to perceive changes in SST in response to varying degrees of severity of the mammary gland infection as reflected by the CMT score, suggesting that as a noninvasive tool, IRT can be employed for screening dairy cows for mastitis.

Udder shape and teat-end lesions as potential risk factors for high somatic cell counts and intra-mammary infections in dairy cows

The association of common bacterial pathogens in milk samples during calving with udder shape or the presence of 'teat-end' lesions was investigated in 240 dairy cows from two herds. Sixty-three of 120 cows (53%) in one herd (herd A) and 54/120 animals (45%) in a second herd (herd B) had normal-shaped udders. The remaining animals had udder shapes defined as follows: large pendulous (18% herd A, 26% herd B); large between hindquarter (10% herd A, 17% herd B); overall small (8% herd A, 5% herd B); or small but pendulous (11% herd A, 7% herd B). At calving teat-end lesions were present in 63% and 76% of the quarters of herd A and B animals, respectively. There was no herd effect on udder shape or teat-end lesions. Analysis of variance revealed that udder shape and teat-end lesions did not have a significant association with quarter somatic cell count. However there was some association between mammary infection and udder shape and teat-end lesions. Compared to other udder shapes, cows with large between hindquarter shape had significantly less Staphylococcus aureus and Streptococcus uberis infection (P<0.001). There was a similar albeit less significant negative association with Escherichia coli infection (P<0.01). Infection with Streptococcus agalactiae and Streptococcus dysgalactiae was more frequent in cows with large pendulous and overall small udder conformations. The results also suggest an association between intra-mammary infection at calving and the presence of hyperkeratotic teat-end lesions, given that S. aureus, coagulase-negative staphylococci, S. uberis, S. agalactiae and E. coli were cultured from significantly more quarters with such lesions than from quarters without lesions or with other types of lesion (P<0.001).

Prevalence, incidence and risk factors of heifer mastitis

Traditionally heifers, as calves and as primiparae, have been thought of as a group as free of mastitis. Without appreciable lacteal secretion, there is reduced nutrient fluid available to support growth of intramammary pathogens. Contagious mastitis is primarily transmitted at milking time and the milking process affects the patency of the teat orifice which can increase the risk of development of environmental mastitis. Logically therefore prepartum heifers should be free of intramammary infections. During the last 20 years there have been numerous investigations describing the nature of mastitis in heifers and thus the dogma that heifers are free of this disease has been challenged. The purpose of this manuscript is to review that literature describing heifer intramammary infections that cause both subclinical and clinical disease. Mammary quarter infection prevalence ranges between 28.9–74.6% prepartum, and 12.3–45.5% at parturition. Generally, the pathogens that cause mastitis in heifers are the same as those that cause infections in the older cows. In all but one study reviewed, coagulase-negative staphylococci (CNS) are the most prevalent cause of subclinical intramammary infections in heifers. Coagulase-positive staphylococci (CPS) in some studies are the second most prevalent pathogens, while in other studies the environmental mastitis pathogens are more prevalent. The risk factors for subclinical mastitis appear to be season, herd location, and trimester of pregnancy; all suggesting that management can have an impact in control of this disease prepartum. With respect to clinical mastitis, the most prevalent mastitis pathogen has been reported to be CNS in one study and CPS, or environmental mastitis pathogens, in other studies. The heifer is most at risk for clinical mastitis during the periparturient period. Risk factors found are related to diet, mammary gland factors such as edema and leaking of milk, and factors associated with the change in management and introduction of the heifer to the milking herd.

Polymerase Chain Reaction in Detection ofCandida albicansfor Confirmation of Clinical Diagnosis of Nipple Thrush

Breastfeeding MedicineVol. 3, No. 3 LETTER TO THE EDITORPolymerase Chain Reaction in Detection of Candida albicans for Confirmation of Clinical Diagnosis of Nipple ThrushMariana Panjaitan, Lisa H. Amir, Anna-Maria Costa, Elice Rudland, and Sepehr TabriziMariana PanjaitanSearch for more papers by this author, Lisa H. AmirSearch for more papers by this author, Anna-Maria CostaSearch for more papers by this author, Elice RudlandSearch for more papers by this author, and Sepehr TabriziSearch for more papers by this authorPublished Online:8 Sep 2008https://doi.org/10.1089/bfm.2008.0106AboutSectionsPDF/EPUB ToolsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail FiguresReferencesRelatedDetailsCited ByABM Clinical Protocol #4: Mastitis, Revised March 2014Mammary candidiasis: molecular-based detection of Candida species in human milk samples13 May 2016 | European Journal of Clinical Microbiology & Infectious Diseases, Vol. 35, No. 8Detection of Candida spp. in the vagina of a cohort of nulliparous pregnant women by culture and molecular methods: Is there an association between maternal vaginal and infant oral colonisation?5 October 2015 | Australian and New Zealand Journal of Obstetrics and Gynaecology, Vol. 56, No. 2Influenza Transmission in the Mother-Infant Dyad Leads to Severe Disease, Mammary Gland Infection, and Pathogenesis by Regulating Host Responses8 October 2015 | PLOS Pathogens, Vol. 11, No. 10ABM Clinical Protocol #4: Mastitis, Revised March 2014 Lisa H. Amir and 9 June 2014 | Breastfeeding Medicine, Vol. 9, No. 5Results of Microbial Testing Exploring the Etiology of Deep Breast Pain During Lactation: A Systematic Review and Meta‐analysis of Nonrandomized Trials25 April 2012 | Journal of Midwifery & Women's Health, Vol. 57, No. 4The role of micro-organisms (Staphylococcus aureus and Candida albicans) in the pathogenesis of breast pain and infection in lactating women: study protocol22 July 2011 | BMC Pregnancy and Childbirth, Vol. 11, No. 1MastitisABM Clinical Protocol #4: Mastitis8 September 2008 | Breastfeeding Medicine, Vol. 3, No. 3 Volume 3Issue 3Sep 2008 Information© 2008 Mary Ann Liebert, Inc.To cite this article:Mariana Panjaitan, Lisa H. Amir, Anna-Maria Costa, Elice Rudland, and Sepehr Tabrizi.Polymerase Chain Reaction in Detection of Candida albicans for Confirmation of Clinical Diagnosis of Nipple Thrush.Breastfeeding Medicine.Sep 2008.185-187.http://doi.org/10.1089/bfm.2008.0106Published in Volume: 3 Issue 3: September 8, 2008PDF download

Evaluation of direct and indirect measures of quarter milk from crossbred buffaloes

ABSTRACTSomatic cell count (SCC), bacteriological findings and electrical conductivity (EC) were measured in milk from 216 quarters of 54 Murrah crossbred buffaloes for characterization of buffalo milk. Mean SCC in normal, subclinical and clinical mastitic milk was 171, 799 and 6039 × 103/mL, respectively. Coagulase negative Staphylococci (CNS) were the major organisms associated with subclinical mastitis, whereas CNS and coliforms were the predominant organisms in clinical mastitis. EC values were found to be significantly higher in buffalo milk with mammary infection. The best trade‐off between sensitivity and specificity for diagnosing mastitis in buffaloes by EC score was found at the cut‐off value of 3.7 mS/cm. The direct measures such as SCC, EC, bacteriological findings, and appearance of milk were found to be useful for the evaluation of udder health of buffaloes and categorization of milk.

Identification of immune genes and proteins involved in the response of bovine mammary tissue to Staphylococcus aureus infection

BackgroundMastitis in dairy cattle results from infection of mammary tissue by a range of micro-organisms but principally coliform bacteria and Gram positive bacteria such as Staphylococcus aureus. The former species are often acquired by environmental contamination while S. aureus is particularly problematic due to its resistance to antibiotic treatments and ability to reside within mammary tissue in a chronic, subclinical state. The transcriptional responses within bovine mammary epithelial tissue subjected to intramammary challenge with S. aureus are poorly characterised, particularly at the earliest stages of infection. Moreover, the effect of infection on the presence of bioactive innate immune proteins in milk is also unclear. The nature of these responses may determine the susceptibility of the tissue and its ability to resolve the infection.ResultsTranscriptional profiling was employed to measure changes in gene expression occurring in bovine mammary tissues sampled from three dairy cows after brief and graded intramammary challenges with S. aureus. These limited challenges had no significant effect on the expression pattern of the gene encoding β-casein but caused coordinated up-regulation of a number of cytokines and chemokines involved in pro-inflammatory responses. In addition, the enhanced expression of two genes, S100 calcium-binding protein A12 (S100A12) and Pentraxin-3 (PTX3) corresponded with significantly increased levels of their proteins in milk from infected udders. Both genes were shown to be expressed by mammary epithelial cells grown in culture after stimulation with lipopolysaccharide. There was also a strong correlation between somatic cell count, a widely used measure of mastitis, and the level of S100A12 in milk from a herd of dairy cows. Recombinant S100A12 inhibited growth of Escherichia coli in vitro and recombinant PTX3 bound to E. coli as well as C1q, a subunit of the first component of the complement cascade.ConclusionThe transcriptional responses in infected bovine mammary tissue, even at low doses of bacteria and short periods of infection, probably reflect the combined contributions of gene expression changes resulting from the activation of mammary epithelial cells and infiltrating immune cells. The secretion of a number of proinflammatory cytokines and chemokines from mammary epithelial cells stimulated by the bacteria serves to trigger the recruitment and activation of neutrophils in mammary tissue. The presence of S100A12 and PTX3 in milk from infected udder quarters may increase the anti-bacterial properties of milk thereby helping to resolve the mammary tissue infection as well as potentially contributing to the maturation of the newborn calf epithelium and establishment of the newborn gut microbial population.

Early Increases in Superantigen-Specific Foxp3+Regulatory T Cells during Mouse Mammary Tumor Virus Infection

Mouse mammary tumor virus (MMTV) is a milk-borne betaretrovirus that has developed strategies to exploit and subvert the host immune system. Here, we show in a natural model of MMTV infection that the virus causes early and progressive increases in superantigen (SAg)-specific Foxp3(+) regulatory T cells (T(reg)) in Peyer's patches (PP). These increases were shown to be dependent on the presence of dendritic cells. CD4(+) CD25(+) T cells from the PP of infected mice preferentially suppress the proliferative response of T cells to SAg-expressing antigen-presenting cells ex vivo. We investigated the influence of the depletion of CD25(+) cells at different stages of the infection. When CD25(+) cells were depleted before MMTV infection, an increase in the number of PP SAg-cognate Foxp3(-) T cells was found at day 6 of infection. Since the SAg response is associated with viral amplification, the possibility exists that T(reg) cells attenuate the increase in viral load at the beginning of the infection. In contrast, depletion of CD25(+) cells once the initial SAg response has developed caused a lower viral load, suggesting that at later stages T(reg) cells may favor viral persistence. Thus, our results indicated that T(reg) cells play an important and complex role during MMTV infection.

Bovine mastitis associated with Prototheca blaschkeae.

Bovine mastitis is an important and complex disease responsible for economic losses in the dairy industry. Biotype II strains of the green alga Prototheca zopfii can be involved, most often resulting in chronic mastitis of difficult treatment associated with reduced milk production. This type of infection is rare, but the number of reported cases is increasing worldwide. In order to determine the kind of species involved in mastitis by Prototheca in northwest Portugal, 41 Prototheca isolates were genetically characterized. The algae are part of Prototheca isolates that were collected during a 6-year period, isolated from the milk of 41 dairy cows in a total of 22 herds with a history of increasing somatic cell counts, mild clinical signs of udder infection, and unsuccessful response to the usual therapy. PCR amplification of the 18S ribosomal DNA (rDNA), amplified rDNA restriction analysis, and phylogenetic analyses of the 18S rDNA sequences were performed. Thirty-seven isolates were identified as P. zopfii var. hydrocarbonea and four as Prototheca blaschkeae. These data suggest a high incidence of P. zopfii var. hydrocarbonea mastitis in the region and demonstrate for the first time the involvement of P. blaschkeae with bovine mammary gland infections.

In vivo imaging of NF-κB activity during Escherichia coli-induced mammary gland infection

In mammary gland infections, the contribution of NF-kappaB is not well defined, and was therefore investigated following intramammary inoculation of Escherichia coli. Non-invasive real-time in vivo imaging of the transcription factor activation was performed in mammary glands of transgenic mice expressing luciferase under the control of NF-kappaB. Bacterial inoculation resulted in a major increase in luminescence as compared with control glands. This activation was confirmed by immunohistochemical nuclear staining of the NF-kappaB p65 subunit in mammary epithelium of infected glands, while nuclear p50 was not detected. The systemic response to the intramammary inoculation of Escherichia coli was also studied. NF-kappaB activation in the liver increased over time, and a relatively mild but longer-lasting response was observed as compared with the acute hepatic response of mice receiving lipopolysaccharide. This systemic reaction was confirmed by increased circulating levels of the acute phase protein serum amyloid A, tumour necrosis factor-alpha and interleukin-6. In addition, high concentrations of both cytokines in the mammary gland inoculated with bacteria showed that the infection was also well established at the local level. These results indicate that in vivo monitoring of NF-kappaB activation is an attractive novel approach to study mammary gland inflammation, and that this transcription factor is imperative in the early stages of the host immune response towards coliform intramammary infections, both at the local and systemic level.

Influence of oestrus on the heat stability and other characteristics of milk from dairy goats

We examined the heat stability, somatic cell count (SCC), pH, fat, protein and lactose content of milk from goats during the oestrous period, in order to investigate evidence of possible oestrus effects on milk physical and chemical properties. Goats free from mammary infections were ranked on average SCC from three tests so that they could be stratified randomly in pairs to synchronized oestrus or left as unsynchronized non-oestrus controls. The synchronisation consisted of insertion of an intravaginal progesterone-releasing device for 17 d, and introduction of the bucks the day of the device removal (D0). The repeated measurements analysis of variance model included the fixed effects of the experimental group (oestrus or control) and day and the corresponding interaction and also the random effect of doe. Reduced milk-heat stability, increased SCC, increased protein content and reduced pH were found in the milk samples of the oestrus group on D1, 2 and 3. The fat and lactose content of the milk was not affected by oestrus. These data indicate that the milk of goats during the mating period has reduced heat stability and, therefore, that dilution into bulk tanks should be recommended to avoid clotting when milk is intended for high thermal treatment.