A Novel Pathway for Porcine Epidemic Diarrhea Virus Transmission from Sows to Neonatal Piglets Mediated by Colostrum.

The mechanisms of colostrum-mediated virus transmission are difficult to elucidate because of the absence of experimental animal models and the difficulties in tissue sample collection from mothers in the peripartum period. Porcine epidemic diarrhea virus (PEDV) is a reemerging enteropathogenic coronavirus that has catastrophic impacts on the global pig industry. PEDV primarily infects neonatal piglets by multiple routes, especially 1- to 2-day-old neonatal piglets. Here, our epidemiological investigation and animal challenge experiments revealed that PEDV could be vertically transmitted from sows to neonatal piglets via colostrum, and CD3+ T cells in the colostrum play an important role in this process. The results showed that PEDV colonizing the intestinal epithelial cells (IECs) of orally immunized infected sows could be transferred to CD3+ T cells located just beneath the IECs. Next, PEDV-carrying CD3+ T cells, with the expression of integrin α4ß7 and CCR10, migrate from the intestine to the mammary gland through blood circulation. Arriving in the mammary gland, PEDV-carrying CD3+ T cells could be transported across mammary epithelial cells (MECs) into the lumen (colostrum), as illustrated by an autotransfusion assay and an MECs/T coculture system. The PEDV-carrying CD3+ T cells in colostrum could be interspersed between IECs of neonatal piglets, causing intestinal infection via cell-to-cell contact. Our study demonstrates for the first time that colostrum-derived CD3+ T cells comprise a potential route for the vertical transmission of PEDV. IMPORTANCE The colostrum represents an important infection route for many viruses. Here, we demonstrate the vertical transmission of porcine epidemic diarrhea virus (PEDV) from sows to neonatal piglets via colostrum. PEDV colonizing the intestinal epithelial cells could transfer the virus to CD3+ T cells located in the sow intestine. The PEDV-carrying CD3+ T cells in the sow intestine, with the expression of integrin α4ß7 and CCR10, arrive at the mammary gland through blood circulation and are transported across mammary epithelial cells into the lumen, finally leading to intestinal infection via cell-to-cell contact in neonatal piglets. Our study not only demonstrates an alternative route of PEDV infection but also provides an animal model of vertical transmission of human infectious disease.

Vertical transmission of SARS-CoV2 during pregnancy: A high-risk cohort.

OBJECTIVE: Identify the potential for and risk factors of SARS-CoV-2 vertical transmission. METHODS: Symptomatic pregnant women with COVID-19 diagnosis in whom PCR for SARS-CoV-2 was performed at delivery using maternal serum and at least one of the biological samples: cord blood (CB), amniotic fluid (AF), colostrum and/or oropharyngeal swab (OPS) of the neonate. The association of parameters with maternal, AF and/or CB positivity and the influence of SARS-CoV-2 positivity in AF and/or CB on neonatal outcomes were investigated. RESULTS: Overall 73.4% (80/109) were admitted in hospital due to COVID-19, 22.9% needed intensive care and there were four maternal deaths. Positive RT-PCR for SARS-CoV-2 was observed in 14.7% of maternal blood, 13.9% of AF, 6.7% of CB, 2.1% of colostrum and 3.7% of OPS samples. The interval between COVID-19 symptoms and delivery was inversely associated with SARS-CoV-2 positivity in the maternal blood (p = 0.002) and in the AF and/or CB (p = 0.049). Maternal viremia was associated with positivity for SARS-CoV-2 in AF and/or CB (p = 0.001). SARS-CoV-2 positivity in the compartments was not associated with neonatal outcomes. CONCLUSION: Vertical transmission is possible in pregnant women with COVID-19 and a shorter interval between maternal symptoms and delivery is an influencing factor.

Efficacy of the spray-drying treatment to inactivate the bovine leukemia virus in bovine colostrum.

Previous studies have shown the presence of bovine leukemia virus (BLV) in colostrum and milk of naturally infected cows. The relationship between virus or provirus and specific antibodies in these secretions is particular to each infected cow and will probably determine whether the consumption of colostrum or milk from these naturally infected dams provides an infective or a protective effect in recipient calves. Our recent findings suggest that this issue is a key point in BLV transmission in very young calves. Based on this, the aim of the present study was to determine the effect of the spray-drying treatment of colostrum on BLV infectivity. The treatment was done on scale-down conditions, using fresh colostrum from BLV-negative cows spiked with infective BLV. Residual infectivity was tested in susceptible lambs. Lambs inoculated with colostrum spiked with BLV-infected cells or cell-free BLV showed evidence of infection 60 d after inoculation, whereas none of the lambs inoculated with spray-dried colostrum showed evidence of infection 60 d after inoculation. These results provide direct evidence that the experimental spray-drying process used in this study was effective in inactivating infectious BLV in colostrum. These findings suggest that the risk for BLV transmission could be reduced if milk and colostrum were treated by spray-drying prior to consumption in dairy facilities. The effect of spray-drying on the functional properties and stability of the antibodies present in colostrum under long-term storage should be further investigated.

Dynamics of perinatal bovine leukemia virus infection.

BACKGROUND: Bovine leukemia virus (BLV) is highly endemic in many countries, including Argentina. As prevention of the spread from infected animals is of primary importance in breaking the cycle of BLV transmission, it is important to know the pathophysiology of BLV infection in young animals, as they are the main source of animal movement. In this work, we determined the proviral load and antibody titers of infected newborn calves from birth to first parturition (36 months). RESULTS: All calves under study were born to infected dams with high proviral load (PVL) in blood and high antibody titers and detectable provirus in the colostrum. The PVL for five out of seven calves was low at birth. All animals reached PVLs of more than 1% infected peripheral blood mononuclear cells (PBMCs), three at 3 months, one at 6 months, and one at 12 months. High PVLs persisted until the end of the study, and, in two animals, exceeded one BLV copy per cell. Two other calves maintained a high PVL from birth until the end of the study. Antibody titers were 32 or higher in the first sample from six out of seven calves. These decayed at 3-6 months to 16 or lower, and then increased again after this point. CONCLUSIONS: Calves infected during the first week of life could play an active role in early propagation of BLV to susceptible animals, since their PVL raised up during the first 12 months and persist as high for years. Early elimination could help to prevent transmission to young susceptible animals and to their own offspring. To our knowledge, this is the first study of the kinetics of BLV proviral load and antibody titers in newborn infected calves.

Mother-to-Child Transmission of Arboviruses during Breastfeeding: From Epidemiology to Cellular Mechanisms.

Most viruses use several entry sites and modes of transmission to infect their host (parenteral, sexual, respiratory, oro-fecal, transplacental, transcutaneous, etc.). Some of them are known to be essentially transmitted via arthropod bites (mosquitoes, ticks, phlebotomes, sandflies, etc.), and are thus named arthropod-borne viruses, or arboviruses. During the last decades, several arboviruses have emerged or re-emerged in different countries in the form of notable outbreaks, resulting in a growing interest from scientific and medical communities as well as an increase in epidemiological studies. These studies have highlighted the existence of other modes of transmission. Among them, mother-to-child transmission (MTCT) during breastfeeding was highlighted for the vaccine strain of yellow fever virus (YFV) and Zika virus (ZIKV), and suggested for other arboviruses such as Chikungunya virus (CHIKV), dengue virus (DENV), and West Nile virus (WNV). In this review, we summarize all epidemiological and clinical clues that suggest the existence of breastfeeding as a neglected route for MTCT of arboviruses and we decipher some of the mechanisms that chronologically occur during MTCT via breastfeeding by focusing on ZIKV transmission process.

Colostral transmission of porcine circovirus 2 (PCV-2): reproduction of post-weaning multisystemic wasting syndrome in pigs fed milk from PCV-2-infected sows with post-natal porcine parvovirus infection or immunostimulation.

Post-weaning multisystemic wasting syndrome (PMWS) was reproduced in pigs fed colostrum and milk from porcine circovirus 2 (PCV-2)-infected sows and infected post-natally with porcine parvovirus (PPV) or immunostimulated. Pregnant sows were inoculated intranasally with either PCV-2 (n=5) or PCV-2-free PK-15 cell lysates (control, n=10) 3 weeks before the expected farrowing date. Newborn piglets from five of the control sows were introduced to PCV-2-infected sows (n=6 for each sow) and allowed to feed on the colostrum for 12 h and then given 15 ml milk five times a day for 7 days. Newborn piglets from the other five control sows were fed colostrum and milk from their own sows. After 7 days, two piglets from each group were randomly selected to confirm PCV-2 infection. Twenty-one pigs fed by PCV-2-infected sows were randomly divided into three groups and subjected to post-natal PPV infection (group 1), immunostimulation (group 2) or no post-natal treatment (group 3). Twenty-one pigs fed by uninfected sows were also randomly divided and subjected to post-natal PCV-2 and PPV infection (group 4), post-natal PCV-2 infection (group 5) or no treatment (group 6, negative control). Body weight was significantly greater in group 6 than in groups 1, 2 and 4 at 49, 52, 56, 59 and 63 days of age. The typical granulomatous inflammatory reaction and lymphoid depletion of PMWS was observed in the lymph nodes of groups 1, 2 and 4 at 63 days of age. Group 3 had significantly fewer PCV-2-positive cells than groups 1, 2 and 4. In conclusion, PCV-2 shed from colostrum and milk is infectious and reproduces PMWS with post-natal PPV infection or immune stimulation.

Negative Transmission of SARS-CoV-2 to Hand-Expressed Colostrum from SARS-CoV-2-Positive Mothers.

Aim: The objective of our study was to determine whether the SARS-CoV-2-positive mothers transmit the virus to their hand-expressed colostrum. Methods: This is an observational prospective study that included pregnant women who tested positive for SARS-CoV-2 by PCR test on a nasopharyngeal swab at the moment of childbirth and who wanted to breastfeed their newborns. A colostrum sample was obtained from the mothers by manual self-extraction. To collect the samples, the mothers wore surgical masks, washed their hands with an 85% alcohol-based gel, and washed their breast with gauze that was saturated with soap and water. Results: We obtained seven colostrum samples from different mothers in the first hours postdelivery. SARS-CoV-2 was not detected in any of the colostrum samples obtained in our study. Conclusion: In our study, breast milk was not a source of SARS-CoV-2 transmission. Hand expression (assuring that a mask is used and that appropriate hygienic measures are used for the hands and the breast), when direct breastfeeding is not possible, appears to be a safe way of feeding newborns of mothers with COVID-19.

Analysis of the presence of cutaneous and mucosal papillomavirus types in ductal lavage fluid, milk and colostrum to evaluate its role in breast carcinogenesis.

Several independent studies have presented evidence for the involvement of human papillomaviruses (HPV) in the aetiology of human breast cancer, while others have reported the opposite findings. Here, we have analysed by a high sensitive multiplex PCR-based method the prevalence of alpha mucosal and beta cutaneous HPV DNA in 90 ductal lavages, colostrum and milk. Ten of the 70 DLs analyzed (14%) contained a single or multiple beta HPV types, while DNA from mucosal high-risk HPV types was detected in only one sample (1/70). A strong reduction of HPV positivity in DL fluids was observed in 45 specimens collected after removal of the superficial layers of the nipple epidermis. All DLs were negative for the mucosal low-risk HPV types 6 and 11. Finally, HPV positivity was low in colostrum and milk. Our data show that DNA of alpha mucosa and beta cutaneous HPV types are rarely present in the breast fluids and suggest that a direct role of HPV in breast carcinogenesis is unlikely.

Evidence of Torque teno virus (TTV) vertical transmission in swine.

Routes of swine torque teno virus (TTV) transmission have been minimally investigated in the pig population. Current knowledge suggests the faecal-oral route as the most probable way of viral dissemination. Other transmission routes, such as mother-to-infant, have been studied in humans, but no information is available for swine. Thus, the objective of the present study was to determine the prevalence of two swine TTV genogroups, TTV1 and TTV2, in colostrum samples (n=61) and sera samples from sows (n=10) and stillborn pigs coming from them (n=30). Colostrum was fractioned into two components, milk whey and cell pellets, and 26 out of 61 milk whey samples and 30 out of 58 cell pellets analyzed contained TTV1 or TTV2 genomes, respectively, detected by specific PCR methods. Six and 3 out of 10 serum samples from sows were positive for TTV1 and TTV2 DNA, respectively. Finally, 15 out of 30 sera from stillborns were PCR positive for TTV1, but only 2 were TTV2 positive. Positive stillborns were always infected with the same TTV genogroup as their mothers. However, TTV sequence analysis determined that sequences obtained from sows and their stillborns were not identical. In conclusion, our results indicated that swine TTVs can be transmitted vertically, and suggest that different sow-to-piglet transmission routes may coexist, including transplacental/intra-uterine as well as through lactation. This study represents the first description of swine TTV presence in colostrum and stillborn piglets.

Prevalence of bovine viral diarrhea virus infections in alpacas in the United States.

OBJECTIVE: To determine the prevalence of bovine viral diarrhea virus (BVDV)-infected alpaca herds in the United States and investigate factors associated with seropositive herd status and, subsequently, determine the proportion of animals within seropositive alpaca herds that are persistently infected (PI) carriers for BVDV, obtain information regarding previous herd exposure to BVDV, determine titers of anti-BVDV antibodies of dams, and ascertain whether individual seropositive crias had received supplemental colostrum at birth. DESIGN: Prevalence study. ANIMALS: 63 alpaca herds with >or= 12 registered female alpacas. PROCEDURES: 250 alpaca breeders were randomly selected from 562 eligible herds listed in the Alpaca Owner and Breeders Association membership directory and mailed a voluntary participation request. Sixty-three alpaca breeders participated in the study. From each herd, blood samples from >or= 4 crias were tested for BVDV, BVDV RNA, and serum neutralizing antibodies against BVDV. A region of the genome of BVDV recovered from PI crias was sequenced to determine genetic homology. RESULTS: Among the 63 herds, 16 (25.4%) had seropositive crias and 4 (6.3%) had PI crias. Infections in 3 of the 4 herds with PI crias were linked as evidence by the genetic homologies of viruses. In addition to PI crias, feeding supplemental colostrum was associated with herd seropositivity. CONCLUSIONS AND CLINICAL RELEVANCE: Results confirmed the importance of BVDV infections in alpacas in the United States and highlighted the importance of determining the BVDV infection status of animals before they are commingled to limit exposure of herds to BVDV infection.

Compartmentalization of Subtype A17 of Small Ruminant Lentiviruses between Blood and Colostrum in Infected Goats Is Not Exclusively Associated to the env Gene.

The compartmentalization of small ruminant lentiviruses (SRLVs) subtype A17 was analyzed in colostrum and peripheral blood leukocyte cells of three naturally infected goats. This study aimed to analyze heterogeneity of the SRLV env (V4V5) gene, which encodes neutralizing epitopes of SU glycoprotein, the gag gene encoding capsid protein (CA), and LTR, a noncoding region, responsible for determination of cell tropism. Compartmentalization was assessed using six established tree or distance-based methods, including permutation test to determine statistical significance. We found statistical evidence of compartmentalization between blood and colostrum in all infected goats although phylogenetic evidence of such compartmentalization was not obvious. Our study demonstrated that compartmentalization is not exclusively specific to the env gene, as we revealed that gag and LTR sequences are also compartmentalized between blood and colostrum. The work also confirms the combined use of different methods as essential for reliable determination of intrahost viral compartmentalization. Identifying and characterizing distinct viral subpopulations and the genetic evolution of SRLV in specific anatomical sites enhances our overall understanding of SRLV pathogenesis, immune control, and particularly virus transmission.

Colostrum and milk can transmit jaagsiekte retrovirus to lambs.

Ovine pulmonary adenocarcinoma (OPA) is a contagious disease caused by jaagsiekte sheep retrovirus (JSRV). In the three studies performed, we have obtained data of the importance of colostrum/milk (C/M) in the transmission of JSRV. In the first study, a group of sheep from a flock with a long history of OPA, samples from colostrum and peripheral blood leucocytes (PBLs) were collected. Two specific PCRs (U3-LTR and env of the JSRV) were carried out. Using U3PCR 8/34 sheep were positive in colostrum whereas with envPCR 7/34 were positive. From these animals only one was positive with U3PCR in the PBLs. Evidence of the transmission of JSRV infection by C/M was obtained in two more separate studies. In the second study, PBLs from five lambs from JSRV+ ewes and two from JSRV-ewes were tested by the U3PCR. They were fed C/M by their mothers during 3 months and slaughtered 7 months after birth. Three out of five lambs from the JSRV+ sheep become PBL positive at 3-4 months old and the other two were also positive at 4-6 months of age. One lamb of the JSRV-sheep became also PBL positive at an age of 3 months. In the third study, a group of lambs from JSRV negative mothers were fed with C/M from JSRV+ sheep and housed in separate unit. For comparison, another group of the same origin and maintained in another different unit, were fed with C/M containing a JSRV virus preparation. All lambs were blood sampled monthly and JSRV infection was detected as early as 15 days and several times onwards in both groups. Control groups fed with C/M from JSRV free flock and JSRV blood test negative sheep were always negative. Together these results indicate that suckling is an important natural transmission route for JSRV.

Porcine circovirus type 3 (PCV3) shedding in sow colostrum.

The major objective of this work was to investigate the shedding of porcine circovirus type 3 (PCV3) in sow colostrum. PCV3 titers in the serum and colostrum samples of 38 sows were determined using qPCR. Interestingly, this is the first report regarding the identification of PCV3 from the colostrum samples. In the studied farm, the prevalence of PCV3 in the colostrum samples was 44.74% (17/38). When sows were grouped based on the PCV3 titers in the serum into the "High-viremic", "Low-viremic" and "Non-viremic" sows, it was shown that the High-viremic sows showed significantly higher PCV3 colostrum prevalence (100%; 9/9) with the PCV3 titers ranging from 4.01 to 7.33 genomic copies/mL. The results indicated that PCV3 in the colostrum might be partly influenced by the viremic stage of the infection. However, the results also showed that approximately 41% of sows shedding PCV3 with low titers in the colostrum (7/17) were non-viremic sows. In conclusion, this study identified the presence of PCV3 in sow colostrum. Clinical impacts and mechanisms of colostrum shedding of PCV3 should be further investigated.

Breastfeeding, breast milk and viruses.

BACKGROUND: There is seemingly consistent and compelling evidence that there is no association between breastfeeding and breast cancer. An assumption follows that milk borne viruses cannot be associated with human breast cancer. We challenge this evidence because past breastfeeding studies did not determine "exposure" of newborn infants to colostrum and breast milk. METHODS: We conducted a prospective review of 100 consecutive births of infants in the same centre to determine the proportion of newborn infants who were "exposed" to colostrum or breast milk, as distinct from being fully breast fed. We also report a review of the breastfeeding practices of mothers of over 87,000 newborn infants in the Australian State of New South Wales. This study was approved by the Human Research Ethics Committee of the University of New South Wales (Sydney, Australia). Approval 05063, 29 September 2005. RESULTS: Virtually all (97 of 100) newborn infants in this centre were "exposed" to colostrum or breast milk whether or not they were fully breast fed. Between 82.2% to 98.7% of 87,000 newborn infants were "exposed" to colostrum or breast milk. CONCLUSION: In some Western communities there is near universal exposure of new born infants to colostrum and breast milk. Accordingly it is possible for the transmission of human milk borne viruses. This is contrary to the widespread assumption that human milk borne viruses cannot be associated with breast cancer.

Decreased periparturient transmission of bovine leukosis virus in colostrum-fed calves.

BACKGROUND: The relation between calf bovine leukosis virus (BLV) infection status and colostrum ingestion is unclear. Two conclusions have been drawn from previous studies. One suggests that colostrum ingestion transmits BLV to neonatal calves. The second suggests that colostral antibodies are protective. HYPOTHESIS: Colostrum from BLV-positive cattle is protective in naturally exposed calves. ANIMALS: Twelve colostrum-deprived Holstein calves and 20 colostrum-fed Holstein calves born to BLV-infected cows. METHODS: Prospective study. Colostrum-deprived calves were tested weekly by enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) tests for BLV antibody and provirus for 12 weeks or until the animal became positive for BLV infection. Colostrum-fed calves were fed colostrum derived from BLV-positive cows. Thereafter, ELISA and PCR tests for BLV antibody and provirus were performed every other week until 2 consecutive negative ELISA tests or 1 positive PCR test was achieved. The proportion of calves that converted to BLV-positive status was calculated for each group and compared between groups by using the Fisher exact test. RESULTS: Four of 12 colostrum-deprived calves (33%) became BLV positive, whereas 0 of 20 colostrum-fed calves (0%) became BLV positive. The proportion of calves that became infected was significantly higher in the colostrum-deprived group (P = .014). CONCLUSIONS AND CLINICAL RELEVANCE: Calves born to BLV-positive cows are exposed during parturition, and a proportion of these calves will become infected with BLV. Administration of colostrum from BLV-positive cows greatly decreases the risk of infection.

PCR detection of colostrum-associated Maedi-Visna virus (MVV) infection and relationship with ELISA-antibody status in lambs.

A recent large-scale experimental study showed that bottle-feeding ovine colostrum from seropositive ewes results in high MVV-seroconversion in lambs. In contrast, relatively few lambs that naturally suckled colostrum from seropositive dams seroconverted as a result of it. Furthermore, lambs fed uninfected bovine colostrum readily seroconverted when mixed with ovine-colostrum lambs indicating that horizontal MVV transmission between lambs was efficient. MVV-infection was further investigated in the same samples using two PCR tests targeting sequences in the long-terminal repeats (LTR) and POL MVV genes. PCR-tests confirmed previous serological findings. However, the LTR-PCR was more sensitive and allowed detecting infection earlier than the other tests, including 5-8% of new-born lambs from seropositive dams, providing more evidence that prenatal MVV-infection may be more important than considered. The degree of agreement between PCR and antibody tests in individual samples was low up to 6 months of age and moderate at 10 months-old. Nine percent of lambs were always PCR-negative but seroconverted and 19% of lambs were PCR-positive at least once and did not seroconvert. However, seroconversion was associated with increasing number of times lambs were PCR-positive and ovine colostrum-fed lambs were more frequently PCR-positive than other lambs. The significance of these findings in terms of MVV-infection, epidemiology and control is discussed.

The diagnostic performance of an antibody enzyme-linked immunosorbent assay using serum and colostrum to determine the disease status of a Jersey dairy herd infected with Mycobacterium avium subspecies paratuberculosis.

Colostrum may have the ability to improve the diagnostic accuracy of some tests when compared to serum for important livestock diseases because of the high concentrations of immunoglobulins present within this sample type. The ELISA for Johne's disease is one such test, as it suffers from low sensitivity when testing serum samples collected during the subclinical stage of infection. Blood and colostrum samples were collected from 34 Jersey dairy cows and tested for antibodies against Mycobacterium avium subspecies paratuberculosis (MAP) by ELISA. Fecal samples were also collected and tested by a high-throughput Johne's polymerase chain reaction (HT-J PCR) assay and fecal culture (FC), with the latter being used as the reference test. A receiver operating characteristic (ROC) analysis was performed, and the area under the curve (AUC) was calculated. The HT-J PCR and FC results were also compared. Of the 34 cows in this study, 4 had FC results consistent with MAP infection. The HT-J PCR did not identify any FC-positive cows. Using a 1:20 dilution and sample-to-positive (S/P) ratio cutoff threshold of 0.15, the relative sensitivity values of both serum (AUC 0. 56) and colostrum (AUC 0.63) were 0%. With lower sample dilutions, the relative sensitivity values of serum were 0% (1:2, AUC 0.62; 1:5, AUC 0.55); however, the relative sensitivity value of colostrum was 75% (95% confidence interval [CI]: 19-99%) at a dilution of 1:5, S/P ratio cutoff threshold of 0.15, and AUC of 0.73 (95% CI: 0.55-0.87). The testing of colostrum samples for MAP-specific antibodies by ELISA may provide improved identification of animals in the early stages of infection with MAP when compared with serum samples.

Repeated Vaccination of Cows with HIV Env gp140 during Subsequent Pregnancies Elicits and Sustains an Enduring Strong Env-Binding and Neutralising Antibody Response.

An important feature of a potential vaccine against HIV is the production of broadly neutralising antibodies (BrNAbs) capable of potentially blocking infectivity of a diverse array of HIV strains. BrNAbs naturally arise in some HIV infected individuals after several years of infection and their serum IgG can neutralise various HIV strains across different subtypes. We previously showed that vaccination of cows with HIV gp140 AD8 trimers resulted in a high titre of serum IgG against HIV envelope (Env) that had strong BrNAb activity. These polyclonal BrNAbs concentrated into the colostrum during the late stage of pregnancy and can be harvested in vast quantities immediately after calving. In this study, we investigated the effect of prolonged HIV gp140 vaccination on bovine colostrum IgG HIV Env-binding and BrNAb activity over subsequent pregnancies. Repeated immunisation led to a maintained high titre of HIV Env specific IgG in the colostrum batches, but this did not increase through repeated cycles. Colostrum IgG from all batches also strongly competed with sCD4 binding to gp140 Env trimer and with human-derived monoclonal VRC01 and b12 BrNAbs that bind the CD4 binding site (CD4bs). Furthermore, competition neutralisation assays using RSC3 Env gp120 protein core and a derivative CD4bs mutant, RSC3 Δ371I/P363N, showed that CD4bs neutralising antibodies contribute to the neutralising activity of all batches of purified bovine colostrum IgG. This result indicates that the high IgG titre/avidity of anti-CD4bs antibodies with BrNAb activity was achieved during the first year of vaccination and was sustained throughout the years of repeated vaccinations in the cow tested. Although IgG of subsequent colostrum batches may have a higher avidity towards the CD4bs, the overall breadth in neutralisation was not enhanced. This implies that the boosting vaccinations over 4 years elicited a polyclonal antibody response that maintained the proportion of both neutralising and non-neutralising CD4bs antibodies.