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Many animals differentially express behaviours across the annual cycle as life stages are coordinated with seasonal environmental conditions. Understanding of the mechanistic basis of such seasonal changes in behaviour has traditionally focused on the role of changes in circulating hormone levels. However, it is increasingly apparent that other endocrine regulation mechanisms such as changes in local hormone synthesis and receptor abundance also play a role. Here I review what is known about seasonal changes in steroid hormone receptor abundance in relation to seasonal behaviour in vertebrates. I find that there is widespread, though not ubiquitous, seasonal variation in the expression of steroid hormone receptors in the brain, with such variation being best documented in association with courtship, mating and aggression. The most common pattern of seasonal variation is for there to be upregulation of sex steroid receptors with the expression of courtship and mating behaviours, when circulating hormone levels are also high. Less well-documented are cases in which seasonal increases in receptor expression could compensate for low circulating hormone levels or seasonal downregulation that could serve a protective function. I conclude by identifying important directions for future research.

In this randomized trial involving neonates whose HIV-infected mothers did not receive antenatal antiretroviral therapy (ART), combination ART significantly reduced intrapartum HIV infection, as compared with monotherapy. Three-drug ART had more side effects than two-drug ART. Randomized, controlled studies of postexposure prophylaxis in infants born to late-presenting women with human immunodeficiency virus (HIV) infection who did not receive antiretroviral therapy (ART) in pregnancy have been performed in breast-fed populations 1 – 5 but not in non–breast-fed populations of higher-income countries. Observational studies have shown reduced transmission when zidovudine therapy was initiated within 48 hours after birth and continued for 6 weeks in neonates born to untreated mothers with HIV type 1 (HIV-1) infection, 6 , 7 although transmission rates in this scenario remain as high as 12 to 26%. 6 – 8 In a randomized South African trial of infants born to . . .

Landon Myer and colleagues discuss viral load monitoring for pregnant HIV-positive women and those breastfeeding; ART treatments can suppress viral load and are key to preventing transmission to the child.

Sexually transmitted infections (STIs) including Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), Treponema pallidum (TP), and cytomegalovirus (CMV) may lead to adverse pregnancy and infant outcomes. The role of combined maternal STIs in HIV mother-to-child transmission (MTCT) was evaluated in mother-infant pairs from NICHD HPTN 040. Urine samples from HIV-infected pregnant women during labor were tested by polymerase chain reaction (PCR) for CT, NG, and CMV. Infant HIV infection was determined by serial HIV DNA PCR testing. Maternal syphilis was tested by VDRL and confirmatory treponemal antibodies. A total of 899 mother-infant pairs were evaluated. Over 30% had at least one of the following infections (TP, CT, NG, and/or CMV) detected at the time of delivery. High rates of TP (8.7%), CT (17.8%), NG (4%), and CMV (6.3%) were observed. HIV MTCT was 9.1% (n = 82 infants). HIV MTCT was 12.5%, 10.3%, 11.1%, and 26.3% among infants born to women with CT, TP, NG or CMV respectively. Forty-two percent of HIV-infected infants were born to women with at least one of these 4 infections. Women with these infections were nearly twice as likely to have an HIV-infected infant (aOR 1.9, 95% CI 1.1-3.0), particularly those with 2 STIs (aOR 3.4, 95% CI 1.5-7.7). Individually, maternal CMV (aOR 4.4 1.5-13.0) and infant congenital CMV (OR 4.1, 95% CI 2.2-7.8) but not other STIs (TP, CT, or NG) were associated with an increased risk of HIV MTCT. HIV-infected pregnant women identified during labor are at high risk for STIs. Co-infection with STIs including CMV nearly doubles HIV MTCT risk. CMV infection appears to confer the largest risk of HIV MTCT. NCT00099359.

Social information is widely used by animals to inform decisions made in a variety of contexts. Less well understood is how the state of the information source influences social information use and if social information informs migratory decisions. Furthermore, most studies on social information use in the context of migration focus on obligate migrants, yet social information is predicted to be particularly important for species that exhibit more flexible migratory behavior. We experimentally tested for social cue use during the vernal migratory period in a captive population of pine siskins (Spinus pinus). Pine siskins are nomadic migrants that exhibit a highly flexible spring migratory period that is associated with elevated energy reserves and, in captivity, nocturnal migratory restlessness. Beginning in May, male and female subjects were presented same-sex neighbors that were previously maintained on either a standard photoperiod (control neighbors) or a longer, summer photoperiod (photo-advanced neighbors, who exhibited more advanced reproductive development). We assessed the effect of these differing social cues on subjects over 28 days by monitoring nocturnal migratory behavior, body condition, and reproductive development. Subjects presented with photo-advanced neighbors ceased nocturnal migratory behavior more rapidly than subjects paired with control neighbors. We also observed a relatively stronger response to social cues among female subjects. Rates of change in the body condition and reproductive development of subjects did not differ between treatment groups. This study provides novel insight into how social cues can influence migratory decision-making and provides evidence of sex-specific differences in cue use.Significance statementAnimals often use social information when making decisions. Less well understood is how the state of the information source influences social information use, particularly during migratory decision-making. Using a species of nomadic songbird, we experimentally demonstrate that the decision to terminate migratory behavior depends upon the state of nearby conspecifics. This study informs our understanding of how animals use social information to inform migratory decisions.

Urbanization reflects a major form of environmental change impacting wild birds globally. Whereas urban habitats may provide increased availability of water, some food items, and reduced predation levels compared to rural, they can also present novel stressors including increased light at night, ambient noise, and reduced nutrient availability. Urbanization can also alter levels of brood parasitism, with some host species experiencing elevated levels of brood parasitism in urban areas compared to rural areas. Though the demographic and behavioral consequences of urbanization and brood parasitism have received considerable attention, their consequences for cellular‐level processes are less understood. Telomeres provide an opportunity to understand the cellular consequences of different environments as they are a well‐established metric of biological state that can be associated with residual lifespan, disease risk, and behavior, and are known to be sensitive to environmental conditions. Here we examine the relationships between urbanization, brood parasitism, and blood telomere lengths in adult and nestling song sparrows Melospiza melodia. Song sparrows are a North American songbird found in both urban and rural habitats that experience high rates of brood parasitism by brown‐headed cowbirds Molothrus ater in the urban, but not the rural, sites in our study system. Among adults and nestlings from non‐parasitized nests, we found no differences in relative telomere lengths between urban and rural habitats. However, among urban nestlings, the presence of a brood parasite in the nest was associated with significantly shorter relative telomere lengths compared to when a brood parasite was absent. Our results suggest a novel, indirect, impact of urbanization on nestling songbirds through the physiological impacts of brood parasitism.

Objective. We assessed the association of cigarette smoking with the effectiveness of highly active antiretroviral therapy (HAART) among low-income women. Methods. Data were analyzed from the Women’s Interagency HIV Study, a multisite longitudinal study up to 7.9 years for 924 women representing 72% of all women who initiated HAART between July 1, 1995, and September 30, 2003. Results. When Cox’s regression was used after control for age, race, hepatitis C infection, illicit drug use, previous antiretroviral therapy, and previous AIDS, smokers on HAART had poorer viral responses (hazard ratio [HR]=0.79; 95% confidence interval [CI]=0.67, 0.93) and poorer immunologic response (HR=0.85; 95% CI=0.73, 0.99). A greater risk of virologic rebound (HR=1.39; 95% CI=1.06, 1.69) and more frequent immunologic failure (HR=1.52; 95% CI=1.18, 1.96) were also observed among smokers. There was a higher risk of death (HR=1.53; 95% CI=1.08, 2.19) and a higher risk of developing AIDS (HR=1.36; 95% CI=1.07, 1.72) but no significant difference between smokers and nonsmokers in the risk of death due to AIDS. Conclusions. Some of the benefits provided by HAART are negated in cigarette smokers.

Lynne Mofenson and Heather Watts discuss the context and implications of the study by J. Sibuide and colleagues, which provides a detailed analysis of birth defects in infants with in utero antiretroviral drug exposure in the French Perinatal Cohort. Please see later in the article for the Editors' Summary.

Background. The impact of highly active antiretroviral therapy (HAART) on the natural history of human papillomavirus (HPV) remains uncertain following conflicting reports. Prior studies, however, did not consider patients' adherence to their regimens or HAART effectiveness (viral suppression). Methods. Human immunodeficiency virus (HIV)-positive women (N = 286) who initiated HAART during follow-up in a prospective cohort were assessed semiannually for HPV infection (by polymerase chain reaction) and squamous intraepithelial lesions (SILs). Adherence was defined as use of HAART as prescribed ⩾95% of the time, and effective HAART was defined as suppression of HIV replication. The prevalence, incident detection, and clearance of HPV infection and/or SILs before versus after HAART initiation were compared (using women as their own comparison group). Results. HAART initiation among adherent women was associated with a significant reduction in prevalence (odds ratio, 0.60 [95% confidence interval {CI}, 0.44–0.81]; P = .001), incident detection of oncogenic HPV infection (hazard ratio [HR], 0.49 [95% CI, 0.30–0.82]; P = .006), and decreased prevalence and more rapid clearance of oncogenic HPV-positive SILs (HR, 2.35 [95% CI, 1.07–5.18]; P = .03). Effects were smaller among nonadherent women. The associations of HPV infection and/or SILs with HAART effectiveness were fairly similar to those with HAART adherence. Conclusion. Effective and adherent HAART use is associated with a significantly reduced burden of HPV infection and SILs; this may help explain why rates of cervical cancer have not increased during the HAART era, despite greater longevity.